GENERAL CONSTRUCTION SPECIFICATION

FOR PROPOSED REAR EXTENSION, ROOF

DORMER & INTERNAL ALTERATIONS

AT

20 Cedarfield Road,

Lymm

Dated: Febrauary2018

1.1 GENERAL Whether or not indicated on the drawings, materials and workmanship shall comply with the current Building Regulations, British Standard Codes of practice, NHBC (or other approved BC body) standards and Technical requirements (in particular NHBC Chapter 1.2 “A consistent Approach to Finishes”) and any applicable European EN, DIN or other regulations and Codes of Practice. All materials shall be fixed, applied or mixed in accordance with manufacturers' instructions, specifications and B.B.A Certificates or other third party accreditation. All materials shall be suitable for their purpose. All electrical installations shall comply with the current IEE Regulations and British Standard. All services, installations and work shall comply with the Regulations or recommendations of the respective Statutory Undertakings or Authority to the satisfaction of the relevant inspector, additionally this specification is to be read in conjunction with the following:

1.2 Approved Document A of the Building Regulations Requirement A3 “the building shall be constructed so that in the event of an accident the building will not suffer collapse to an extent disproportionate to the cause”. For Class 2a (apartments up to and including 4 storey) compliance with the requirement can be demonstrated (refer to construction details) whereby the pre-cast concrete floor panels have effective anchorage onto external and internal walls. For further guidance refer to NHBC Technical Guidance Note.

1.3 Useful Website Links

British Standards: www.bsonline.techindex.co.uk (Purchase on line) Building Regulations: www.dclg.gov.uk Barbour Index: www.barbour-index.co.uk BBA: www.bbacerts.co.uk

All dimensions to be checked on site and any discrepancies verified with the Architect or Client.

Work to figured dimensions only, do not scale off drawings.

2.1 PRIVATE DRAINAGE 2.2 Drainage – (General)

The design of all proposed drainage shall comply in full with current Building Regulations Approved Documents, Part H.

All proposed underground drainage to connect where possible by gravity to existing sewers as indicated on the “Drainage Layout” via a new separate drainage system.

Access chambers shall be detailed specifically for their intended depth with covers specified to cater for the intended traffic.

All efforts must be made to identify potential obstructions in the ground, especially where existing drain runs or sewers are shown to pass under any proposed development from existing drainage information.

Where such existing drains are not within the ownership of the development, consultation with the owner of the drain or sewer must be undertaken. Where possible a diversion of the drain to bring the line of the drainage from beneath the building is preferable with the agreement of the owner and Local Authority and Building Inspectors.

Where drains pass through walls concrete lintels are to be used to support masonry above, with all voids filled to prevent the entry of vermin. Alternatively ‘rocker’ pipes with flexible joints may be built in to the wall.

All pipework shall be in flexibly jointed upvc or similar approved system on a bed and surround of granular material in accordance with the manufacturer’s recommendations.

A drain trench should not be excavated lower than the foundations of any nearby building unless:

Where the trench is within 1m of the foundation, the trench around the drain is to be filled

with concrete, finishing level with the underside of the adjacent foundation. Where the trench is further than 1m from the building, the trench around the drain is to be filled with concrete to a level equal to the distance from the building, less 150mm.

Concrete encased drainage shall have movement joints at intervals not exceeding 9m.

Where appropriate, the drainage system shall incorporate measures to eliminate the possibility of rodent access.

After laying gravity drains and/or private sewers, including any necessary concrete or other haunching, surrounding and backfilling, a watertightness test should be undertaken using either an air test or a water test as described in Approved Document Part H. Alternative approaches are detailed in the approved document which refer primarily to BS EN 752 and other British Standards that relate to additional information on design and construction of drainage systems.

When considering reusing existing drainage or connections to public sewers, CCTV surveys should be undertaken to establish the condition and suitability of the existing system.

Pumped drainage systems must be specifically detailed for the project by a specialist designer.

2.3 Foul drainage

When serving no more than 10 dwellings, provide 100mm minimum diameter foul drains laid

to fall, minimum 1:40 gradient, depending on anticipated flow rates. For sewers serving more than 10 dwellings, a 150mm minimum diameter foul drain should be considered. Pipes should be laid with even gradients and any change of gradient/direction should be combined with an access point.

Foul water shall discharge in to a public sewer, either combined or foul sewer.

2.4 Surface Water Drainage

Provide 100mm minimum diameter surface water drains laid to a minimum fall of 1:100, larger diameter pipes or increasing the gradient may be necessary to increase the capacity of the drains. Where larger pipes are to be considered the minimum gradients specified in Approved Document Part H and BS EN 752 Part 4 must be followed. Pipes should be laid with even gradients and any change of gradient/direction should be combined with an access chamber.

Surface water shall discharge in to a public sewer, either combined or surface water.

Where ground conditions are appropriate a ‘soakaway’ may be considered provided that it is no closer than 5m from any building, would not present any pollution hazard to a watercourse and is designed in compliance with BRE Digest 365.

Alternatively, surface water may be discharged into a water course with approval of the Environment Agency, and other interested parties.

2.4.1 Drainage of Paved Areas

Driveways and paving shall be ‘free-drained’ and have a cross gradient of 1:60 (1:40

maximum), discharging away from the dwelling to prevent the build up of surface water on the face of the external wall to a suitable pervious area such as grassland. Where this cannot be achieved, a reverse gradient of at least 500mm from the wall diverting the surface water from the building towards a suitable ‘free-drained’ area or drainage gully should be provided.

Large areas of paving should be drained in accordance with BS EN 7524 : 1998 Provide suitable road gullies to drain surface water from access roads. Refer to Proposed Site layout for gully positions.

2.4.2 Rainwater Goods

Generally, gutters to be 112x52mm PVCu ‘Half Round’ section (NOTE: Section as per Client recommendation) with 68mm diameter PVCu down-pipes, colour and type to be as approved drawings.

Gutters and rwp’s may be omitted from small roofs located at any height providing that the area is less than 6m

2

and no other roof areas drain onto it, in accordance with BS EN 12056- 3:2000. However, where rain water run-off is likely to cause a nuisance, then suitable gutters and down pipes should be provided to small roof areas. Refer to floor layouts and elevations for down-pipe and gully positions.

2.5 Wastes and Drainage Connections above Ground

Waste pipe gradients shall meet with the requirements of Approved Document, Part H. All to comply with BS 5572 : 1978. Waste pipe sizes shall be - Washbasin and bidet: 32mm diameter trap with 75mm deep seal. Bath and shower: 40mm diameter trap and 50mm deep seal. Sink, washing and dishwashing machines: 40mm diameter trap and 75mm deep seal.WC pan (outlet <80mm): 75mm diameter trap and 50mm deep seal. WC pan (outlet >80mm): 100mm diameter trap and 50mm deep seal.

Basins on pedestals shall have McAlpine; Hep VO or similar approved ‘straight-through’ trap. Sanitary fittings within ground floor WC’s shall connect directly to the drainage system providing that the invert from the floor to the drain is less that 1300mm.

A branch discharge pipe should not discharge into a stack lower than 450mm above the invert of the tail of the bend at the foot of the stack for single occupancy dwellings up to 3 storeys. For Apartments this depth may need to be increased in line with the number of apartments served and the number of storeys within the building.

Where shown on approved layouts, 100mm diameter SVP’s may be routed externally provided that there are no externally visible horizontal waste connections.

Such SVP’s shall be taken up the outside of the dwelling and terminated with a proprietary mesh guard, at least 900mm above any adjacent openings that are within 3m.

Internal SVP’s, where located in principle reception rooms and bedrooms including rooms identified by Building Regulations are to be wrapped with 25mm insulation quilt and boxed out in accordance with NHBC Standards.

Offsets within the wet portion of SVP’s are to be avoided, however where they are proposed they must be designed in accordance with BS 5572.

Suitable access panels for rodding purposes shall be provided.

Internal SVP’s shall be connected to suitable flexible pipework and ducted through roof- space to an approved ridge or tile vent terminal.

Alternatively, the SVP may terminate in a suitable air admittance valve, AAV, complying with prEN 12380 (excluding the SVP at the head of a drainage run). The height of the AAV must be above the level of the highest fitting connected to that stack.

2.6 Shower Trays

Where a separate shower tray is fitted and is enclosed on three sides, the shower head shall not be located on the wall opposite the shower screen door/opening. Where a 1200mm long shower tray is used and the door is located on the shortest edge, the shower head may be located opposite the door.

The shower tray shall be fitted with a ‘top-access’ trap located towards the front of the shower.

All shower trays shall have up-stands and have adjustable legs.

2.7 Codes of Practice and BS EN Standards

BS EN 752 pt 1-7 – building drainage

BS EN 295 pt1 / BS EN 1401 pt1 / BS 4660 – Pipes and fittings

BS 5955 – Special protection may be required where pipes are near the ground surface or where they could be damaged by the weight of backfill or traffic load from above.

3.1 SUBSTRUCTURE 3.2 Foundations – (General)

Foundations to be constructed to Specialists or Structural Engineers specification and details based on the Site Investigation and Geotechnical Report.

The design shall take full account of the affect of trees and ground conditions in accordance with NHBC Standards, Chapter 4.2 and Section E1 of Approved Document Part A of the Building Regulations.

Where appropriate, sulphate resisting cement shall be used below ground in accordance with Table 7(a) of BS 5328 : Part 1.

In soils susceptible to heave, adequate protection measurers are to be taken to protect the substructure.

Any porch, bay or similar small projections are to be founded as the main body of the building.

3.2.1 Strip Foundations (for non-aggressive soils and/or other non-hazardous conditions)

Foundations generally to be 450 or 600mm wide x 225mm deep. Minimum depth of foundations, excluding rock sub-strata, should be a minimum depth of 450mm to their underside to avoid the action of frost. This depth will commonly increase in areas subject to long periods of frost or in order to transfer the loadings of the building onto satisfactory ground.

In clay soils subject to volume change on drying such as shrinkable clays with a plasticity index greater than or equal to 10% the foundation design should be taken to a depth where anticipated ground movements will not impair the stability of any part of the building and taking into consideration building near trees, hedgerows and shrubs. The depth should be no less than 0.75m on clay soils with low volume change potential, however may increase to satisfy the transfer loads from the building.

NHBC Standards Section 4.4-D8 specifies the minimum excavation depth in shrinkable soils. The concrete mix must be designed in accordance with the NHBC Standards appendix 2.1-A Tables 1, 2a, 2b, 2c, 3, 4a, 4b and must ensure adequate durability and the following must be taken into consideration:

Mix proportions

Sulphates and acids in ground or groundwater

Chlorides

Aggregates

Alkali-silica reaction

Exposure to climate and performance

Overall performance

Further guidance and more detail can be found by referring to NHBC Standards 2.1-D4

All foundations to be stepped as necessary in accordance with the Approved Document Part A Section 2E-Foundations of Plain Concrete Diagram 22 instructing that foundations stepped on elevation should overlap by twice the height of the step, by the thickness of the foundation or 300mm, whichever is greater and steps in the height of foundations should not be of greater height than the thickness of the foundation. Refer also to NHBC Standards 4.4 – Strip and Trench Fill Foundations Section 4.4 S13b.

On sloping sites foundations trenches should be gradually stepped to ensure that the required foundation depth is reasonably uniform below ground level.

The foundation design shall take into account and be acceptable for building near trees, hedgerows, shrubs and their growth whilst ensuring that all proposed new planting is also to be taken into consideration and evaluated. Guidance should be sought from the NHBC Standards 4.2 paying particular attention to Appendix 4.2A, B and C and the associated tables contained therein.

Maximum depth shall be generally 1.2m.

3.2.2 Trench Fill Foundations (for non-aggressive soils and/or other non-hazardous conditions)

Provide 450 or 600mm wide, GEN 1 (Designated mix) concrete trench fill foundations, top of foundation to be minimum 300mm below finished ground level. The overlap at steps should not be less than twice the step or 1m, which ever is the greater. Refer also to NHBC Standards 4.4 – Strip and Trench Fill Foundations Section 4.4 S13b.

For depths greater than 2.5m the design must be prepared by a Structural Engineer.

3.2 Substructure Walls

Where the top of the foundation is sufficiently low as to be impractical to construct the substructure wall from cavity work with lean mix cavity fill, 300mm wide aircrete foundation blocks, minimum density 660kg/m

3

@ 3% moisture content “Trenchblock” by ‘Thermalite’ or equal approved, with a minimum compressive strength of 4.0N/mm

2

manufactured in accordance with BS 6073: Part 1: 1981, laid in 1:3 masonry cement/sand mortar (sulphate resisting cement where appropriate), built directly off foundations up to minimum 150mm below level of finished external ground level for soil and groundwater conditions up to and including DS4 sulphate levels.

Where greater strength aircrete foundation blocks are required, the “Hi-Strength Trenchblock” by ‘Thermalite’ or equal approved, with a minimum compressive strength of 7.0N/mm

2

should be considered. Minimum density 730kg/m

3

@ 3% moisture content, manufactured in accordance with BS 6073: Part 1: 1981.

300mm wide cavity wall to be built off foundation blocks up to D.P.C level, the external leaf to be approved facing brickwork, FL quality frost resistant. The inner leaf shall be 100mm lightweight aggregate block, density 1400kg/m

3

@ 3% moisture content, “Stranlite” by ‘Plasmor’ or similar, having a thermal conductivity value of 0.46W/mK with a compressive strength to suit the design application. Minimum compressive strength to be 3.5N/mm

2

although 7.0; 10.5N/mm

2

and above are available to suit engineers requirements.

Mortar to be 1:3 cement/sand masonry mix, where appropriate, sulphate resisting Portland cement to BS 4027 shall be used below ground.

A clear cavity of 225mm below that of the dpc in the external wall is generally required; this may be reduced to 150mm where weepholes and other measures are provided that allow the cavity to drain freely.

3.3 Codes of Practice and BS EN Standards

BS 8500 2003 – Concrete mixes

EN 206 – Concrete mixes

BS 8000 1.1 – Workmanship excavation and filling

BS 8000 2.1 – Workmanship mixing and transporting concrete

BS 8000 2.2 – Workmanship sitework with insitu and precast concrete

BS 8004 Code of Practice for foundations

3.4 DPC’s

DPC shall be textured or embossed polyethylene to BS 6515 (except below copings and in parapets). Polyethylene DPC’s should be black and not less than 0.5mm thick (2000 gauge) with 100mm minimum laps, positioned minimum 150mm above adjacent finished external ground level to all external walls. The DPC must extend across the full width of each leaf of the masonry cavity wall and not be compromised by mortar or render bridging the DPC, allowing moisture to bypass the damp proof course. The DPC must not project excessively into the cavity where it may attract mortar droppings. The DPC should be in one continuous piece where practically possible.

The DPM shall be laid and united with the DPM to form a continuous moisture barrier and to be well lapped at angles and intersections using either preformed profiles or alternatively, refer to manufacturers’ instructions. Where necessary due to external levels etc, fix vertical DPC of bituthene or similar approved in cavities, lapped into all DPC’s and DPM’s. Allow for vertical DPC to all reveals where proprietary cavity closures are not used incorporating a DPC.

Alternatively, “Hyload Original” by ‘Ruberoid’ or similar third party accredited pitch polymer dpc can be used for damp-proofing cavity wall constructions. Used vertically, horizontally, below copings, in parapets and as a horizontal cavity tray.

Cavity concrete fill should stop at least 225mm below the base of the DPC however may reduce where special foundations, such as rafts are specified.

Note: Specific precautions may be required in Mining areas, reclaimed or marginal sites to protect against movement, settlement, the passage of methane and radon gases or water ingress.

In such areas alternative sub-structure construction to specialists or Structural Engineers specification/details must be sought.

3.4.1 Codes of Practice and BS EN Standards

BS 6515

BS 8215 – Design and installation of damp proof courses in masonry construction

4.1 GROUND FLOOR CONSTRUCTION The detailing of the ground floor construction shall be in accordance with the DTLR guidance publication ‘Limiting Thermal Bridging and Air Leakage: Robust Construction Details for Dwellings and other Small Buildings’, and BRE publication ‘Thermal Insulation: Avoiding Risks’ 2002 Edition.

For all floors, the construction shall be fully in accordance with Structural Engineers/ Specialists design specification and details.

Ground level below floors to be reduced removing all vegetable matter. These areas shall then be treated with herbicide.

4.2 Concrete Floor Slab

100mm minimum, GEN 2 (Designated Mix) cast in-situ, power floated (in accordance with recommendations of BS 8204), concrete slab, on a suitable damp proof membrane (minimum 0.3mm - 1200 gauge polyethylene, jointed with 300mm minimum laps), laid to form a continuous moisture barrier with the dpc in external cavity walls. 100mm thick “Kingspan K3 Floorboard” comprising a premium performance CFC/HCFC-free rigid phenolic insulation core with low emissivity composite foil facings on both sides by ‘Kingspan Insulation Limited”, or equal approved, thermal conductivity 0.021W/mK, laid strictly in accordance with manufacturers instructions over the whole of the ground floor, laid butt jointed with no gaps, on 150mm thick well consolidated, sand blinded, hardcore or other suitable fill.

Provide a 50mm wide strip of ‘Kingspan K3 Floorboard’ insulation by ‘Kingspan Insulation Limited’, having a thermal conductivity value of 0.021W/mK or equal approved, comprising CFC/HCFC-free rigid phenolic insulation core with low emissivity composite foil facings on both sides, manufactured to BS EN ISO 9002: 1994 or similar approved in the cavity below dpc.

Elemental ‘U’ value to be confirmed for dwelling (P/A ratio to be confirmed for dwelling)

4.3 Concrete Ground Floor – With underfloor void Sub-floor void to be sized to suit local ground conditions, minimum 150mm.

Void to be ventilated with proprietary telescopic cranked ventilators terminating in a plastic air-brick, colour to match surrounding brickwork.

Voids should be ventilated by openings providing not less than 1500mm² of open area per metre run of external wall. Ventilators should be spaced at not more than 2m centres and within 450mm of each end of any wall. Air bricks should be ducted through cavities and be unobstructed.

Every part of the void under suspended ground floor should be thoroughly ventilated through openings on at least two opposite sides. Where this is not possible, effective cross ventilation from opposite sides should be provided by a combination of openings and air ducts.

Provision should be made for ventilation through sleeper walls. If necessary, pipe ducts shall

be incorporated in adjoining solid floors, separating walls or other obstructions.

Concrete beams shall be sized in accordance with the loads and spans dictated by each project. Beams may be doubled-up in specific locations where high concentration loads are anticipated, typically under non load-bearing masonry partitions, etc, as directed by the designer/manufacturer.

4.4 Codes of Practice and BS EN Standards

BS 6891 – Installation of low pressure gas pipework of up to 35mm in domestic premises.

BS EN 13163 – manufacture of EPS insulation

BS 8103-4 – Design of suspended ground floors

BS 8110-1 – Reinforcement

BS 6700 – Design, installation, testing and maintenance of services supplying water for domestic use within buildings and their cartilages

BS 8500 2003 – Concrete mixes

EN 206 – Concrete mixes

BS 8000 4 – Workmanship waterproofing

BS 8000 2.1 – Workmanship mixing and transporting concrete

BS 8000 2.2 – Workmanship sitework with insitu and precast concrete

5.1 EXTERNAL WALLS External cavity walls shall have an overall thickness of 300mm.

5.2 External Walls – up to and including “Severe Exposure”

(As detailed in BRE publication “Thermal Insulation: Avoiding Risks”.)

102mm FL quality, frost resistant, facing bricks or if a render finish is to be used, 100mm thick block as per “Plascon” by ‘Plasmor’ or similar, density 1950kg/m3 @ 3% moisture content, having a thermal conductivity value of 1.06W/mK. Minimum strength 7.0N/mm2 as dictated by Structural Engineers design. These shall be selected taking full regard of overall external appearance and exposure rating of the development.

Both these external leaf options shall have a 100mm nominal cavity partially filled (minimum residual cavity width of 50mm is required), with 50mm thick “K108 Cavity Board” insulation by ‘Kingspan Insulation’, or equal approved, comprising CFC/HCFC-free rigid urethane insulation core with low emissivity composite foil facings on both sides, manufactured to BS EN ISO 9002: 1994 or similar approved.

OR

The inner leaf shall be 100mm lightweight aggregate block, density 1400kg/m3

@ 3% moisture content, “Stranlite” by Plasmor or similar, having a thermal conductivity value of 0.46W/mK. Minimum compressive strength to be 3.5N/mm

2

although 7.0; 10.5N/mm2

and above are available to suit engineers requirements.

Mortar to be 1:4½ or 1:3 cement/sand masonry mix dependant on brick type and exposure (either pre-mixed or site batched in silos as applicable), finished with a ‘bucket handle’ or ‘weathered’ joint. Refer to NHBC Standards, Appendix 6.1-D.

Walls finished internally with either, 12.5mm tapered edged plasterboard (unless otherwise stated on drawing), on dabs with taped and filled joints or taped joints and 3mm plaster skim coat. Plasterboard edges are to be sealed with a continuous ribbon of plasterboard adhesive around wall perimeters and around all socket/switch outlets and at the junctions of window and door frames.

Gypsum wallboard can be used in wet rooms to receive ceramic wall tiling in localised areas such as splash-backs behind kitchen sinks and wash hand basins. In other areas where splashing of water is likely, such as around baths and showers, moisture resistant plasterboard shall be used in accordance with BS 8212 : 1995 and/or the manufacturers recommendations.

The plasterboard shall be cut 15mm shorter than the floor to ceiling height and positioned tight against the ceiling using a ‘foot lifter’. Packers are to be inserted at floor level until the adhesive has set.

A gap of at least 5mm shall be left between the bottom edge of the skirting and the top of the screed or concrete floor finish which shall be sealed with a flexible sealant.

The construction is to give a ‘U’ value of 0.22W/m2

K.

5.3 Mortar

The selection of the appropriate mortar should follow the recommendations given in BS 5628: Part 3; and NHBC Standards Appendix 6.1C:

Sulphate resisting cement should be used where recommended by the brick manufacturer.

Proprietary mortars and admixtures should only be used strictly in accordance with the manufacturer’s recommendations, taking into account the type of masonry unit and its location.

Under gauging of Limebond / sand mixes should be avoided and NHBC guidelines followed Recessed or raked joints should be avoided in conjunction with full fill cavity insulation in areas of Moderate and Severe exposure.

5.4 Render – (General)

The render should be of adequate strength to achieve durability. The colour and texture to be in accordance with the planning approved scheme.

Care should be taken when specifying render to walls with full cavity fill, as the lack of a ventilated cavity can slow down the rate at which the wall dries out.

Rendered finishes should not be used over fully filled cavity walls if the site is in an area classed as Severe or Very Severe exposure to driving rain. See NHBC Standards Appendix 6.1-B.

Rendering may be used on cavity external walls with partial cavity insulation provided a clear cavity width between insulation and outer leaf of at least 50mm nominal is maintained.

Rendering should not be carried across the exposed edge of horizontal DPC’s at any level without a break to prevent the transmission of moisture. Rendering below the horizontal DPC at ground level should be avoided, where the render is stopped at this junction a non-ferrous stop bead creating a bellcast to throw water clear of the exposed wall beneath shall be provided.

Where Acrylic or silicone based through-colour renders are proposed they must be installed fully in accordance with the manufacturer’s recommendations and third party accreditation.

5.4.1 Sand/Cement Render

Two coat render, made up of an undercoat and finishing coat, to BS 5262:1991 on 100mm thick, block outer leaf as specified above with raked joints. Aggregates should consist of clean, well graded sand, complying with BS 1199 and 1200:1976, without too high a proportion of fine material. The rendering mix should be appropriate to the strength of the background. No render coat should be stronger than the background or richer than the preceding coat. Scratch coats shall be trowel applied, between 10mm and 15mm thick. Finish coat should be generally between 6mm and 10mm thick. Adequate time should be allowed for the undercoat to dry out thoroughly before the application of the next coat. For scratch coats and finishing

coats, the generally recommended mix is 1:5 cement/sand by volume, (refer to block manufacturer’s literature). Metal reinforcement, stop beads and drips to rendering should be galvanized or stainless steel, in accordance with BS 5262. External finish shall be either masonry paint or ‘Hi-build’ aqueous based acrylic exterior masonry coating system or similar, colour to be in accordance with the approved drawings.

5.4.2 Through-Colour Render “StoRend Cote” by ‘Sto’ or similar through-colour, third party accredited render system applied in two coats. The first being a 6 to 25mm thick polymer modified cementitious based levelling coat “StoLevell Cote” applied directly to the block outer leaf as specified above. A primer, “Sto-Primer” is then applied prior to the final coat of through colour flexible cement free acrylic render “Stolit K1.5, applied in accordance with the manufacturer’s recommendations.

5.3.2 Codes of Practice and BS EN Standards

BS 5628 – design strengths of bricks, blocks and mortars. Blockwork to conform to the “Special category of manufacturing control” requirements of the British Standard BS EN 771-5 Reconstructed stone

BS 8000 Pt3 – Workmanship masonry

BS 8000 Pt10 – Workmanship plaster and render

BS 5262 DTU 26.1 and DTU 20.1

BRE Thermal Insulation: Avoiding the risks

5.4 Cavity Closers

All openings in external walls shall be constructed so as to reduce thermal bridging, see BRE

publication "Thermal Insulation : Avoiding Risks" good practice guide, 2002 edition for guidance.

100mm wide (or to suit cavity width), proprietary cavity closers to be provided to all window and door openings in external cavity walls to avoid cold bridging, installed strictly in accordance with manufacturers instructions.

Windows shall be positioned within the reveal so that the inner face of the frame overlaps the inner face of the brick outer leaf by 30mm in accordance with the DTLR guidance publication ‘Limiting Thermal Bridging and Air Leakage : Robust Construction Details for Dwellings and other Small Buildings’.

When PVCu windows are specified, the cavity closers will be the window former, specified as part of the window manufacturers system.

Cavities shall be closed at eaves level with proprietary polythene wrapped mineral wool sock.

Note that the DPC is part of the proprietary closure and should be provided around all jambs, heads and cills. Ensure that expanded foam is provided around the frame where necessary to form an air tight seal. A finishing bead of mastic is then to be provided around the opening once the frame is in place.

5.5 Weepholes and Cavity Trays

Figure showing typical installation locations

Stop-end DPC cavity trays should extend at least 150mm beyond the opening and at all times 25mm beyond the lintel. Weepholes, coloured to suit, shall be at 450mm maximum centres, with a minimum of two weepholes per opening, over all lintels and bridges within external cavity walls, i.e. meter boxes and air bricks.

For rendered walls, no specific provision for weepholes is considered necessary, refer to BS 5628 : Part 3 : 2001, however, stop-end cavity trays must be provided.

Where mono pitch roofs abut external cavity walls a code 4 lead flashing with minimum 150mm up-stand combined with a stop-end cavity tray with weepholes at 450mm maximum centres shall be provided. A proprietary flashing with integral roof vent may be considered.

Where a roof slope abuts an external wall, provide a “Cavity Tray Type X” proprietary, third party accredited, combined stepped cavity tray with integral code 4 lead flashing by ‘Cavity Tray Ltd’ or similar, stepped as necessary to suit roof pitch.

Weephole’s, soakers or cover flashings shall be provided and dressed to suit roof tile and cavity tray manufacturers recommendations. All shall be in accordance with current NHBC

Standards, Chapter 6.1 - D6.

5.5.2 Codes of Practice and BS EN Standards

BS 5628: Part 3: use of masonry. Materials and components, design and

workmanship

BS.6398: Specification for bitumen damp-proof courses for masonry

5.7 Lintels & Beams

Galvanized steel lintels designed, tested and manufactured fully in accordance with the British standard, with integral insulation to suit 97mm cavity width. Openings over 1.2m wide may require ‘propping’ until the brickwork over has matured. Minimum bearing of lintels to be 150mm each end. Bearing to be onto complete block. Lintels above internal doors to have minimum 100mm end bearing up to 1200mm clear span and 150mm bearing over 1200mm openings. All lintels to manufacturers’ schedules and calculations. Expanded metal reinforcement over meter boxes. Recon stone or other feature head details are normally supported on the outer flange of the steel lintel.

5.7.1 Recommendations for the installation of concrete floors with steel lintels

The following are guidelines to the safe installation of concrete floor units on steel lintels.

Check that the correct lintel has been installed according to the manufacturer’s schedule.

Avoid shock loading of lintels during the installation of concrete floor units and also any sideways loading while being lifted into position.

Avoid loading new floors with building materials.

Raise both levels of cavity walls together and allow masonry to cure sufficiently before applying heavy loads. Alternatively prop the lintel if large loads are to be applied to fresh masonry.

Bed the lintel on full blocks and allow mortar to cure.

Check that the masonry over the lintel is properly installed and allow no more than 10mm-12mm between the masonry and lintel upstand. The gap should be filled with mortar.

Ensure that the composite part of any composite lintel is fully filled with well jointed masonry and allowed to cure.

Precast flooring units should be laid on a mortar bearing of the full wall width and should not be dragged over supports.

5.7.2 Steel Beams

Any steelwork (to Engineers calculations) to be built-in solid (supported on pad stones to Engineers design) and levelled with steel shims provided and treated with either:

One coat high build zinc phosphate primer and one coat of bituminous paint - to

beams supporting cavity walls or

One coat red oxide or zinc chromatic primer - to beams in floor/roof voids etc or

For externally exposed steel beams - One coat high build zinc phosphate primer at works and site applied intumescent paint (Firetex M77 or equal approved) to give 1hr fire protection with topcoat (Firetex M71 or equal approved).

5.7.3 Internal Lintels

Internal load bearing walls to incorporate pre-stressed concrete lintels to manufacturers calculations and schedules.

Steel lintels can be used in lieu of concrete where they have been designed to be of heavy

duty type and designed of a cavity type construction to avoid additional fire protection. Care must be taken when specifying that all lintels of this type are heavy duty avoid incorrect lintels being installed. All lintels to be as per manufacturers specification and schedules but must take account of the above recommendation which may involve some lintels being over designed to avoid complications on site.

5.7.4 Limiting Thermal Bridging and Air Leakage

Lintels having base plates to have effective conductivity not exceeding 30W/mK. Lintels to be fully filled with insulation Thickness of lintel flanges to be no more than 3.2mm

5.7.5 Codes of Practice and BS EN Standards

BS 5977- Galvanised steel lintels

BS 5950 Structural use of steelwork in buildings

5.8 Wall Ties – (General) – (Drawing / Detail may be required from Structural Engineer)

Generally, wall ties should be spaced above and below dpc as specified.

The new Part E (Resistance to the passage of Sound) classifies wall ties into two types: Type A - For separating & external cavity walls Type B - For external cavity walls where Type A ties are unsuitable. Major manufacturers generally use logos to identify the category of wall ties and this should be confirmed prior to procurement.

Type A Ties These ties must either be butterfly ties to BS1243, and only used in 50mm to 75mm cavities, or ties with a measured dynamic stiffness of <4.8MN/m

3

taking both cavity width and tie density into account.

Independent tests have proven the 200mm Staifix HRT4 Housing Tie has a measured dynamic stiffness of 4.5MN/m

3

at a 75mm cavity and is therefore suitable for separating walls with a 75mm cavity at a standard density of 2.5 per m

2

. Type B Ties These ties must either be double triangle ties to BS1243, and only used in 50mm to 75mm cavities, or ties with a measured dynamic stiffness of <113MN/m

3

taking both cavity width and tie density into account.

Independent tests have proven that the following groups of Ancon and Staifix wall ties easily meet the new Part E requirements for use in external cavity masonry walls:

5.8.1 External Cavity Wall Ties – Type A & B

Domestic housing up to 10m high, for a basic wind speed < 44m/s (< 52m/s in towns and cities), 225mm ‘Staifix HRT4’ by ‘Ancon’ or similar third party accredited, Type 4 stainless steel wall tie to DD140, (capable of spanning 100mm cavity width) positioned at 750mm maximum centres horizontally, staggered at 450mm maximum centres vertically in a diamond formation.

At jamb openings, movement joints, etc, the first ties must be within 150~225mm of the opening and positioned vertically at every block course.

Cavity wall ties should be laid to a slight fall towards the external leaf and be bedded into each leaf by at least 50mm.

For buildings up to 15m where the basic wind speed is < 56m/s, 225mm ‘Staifix RT2’ by ‘Ancon’ or similar BBA approved Type 2 wall tie to DD140 should be used.

Where partial cavity fill insulation is used, 80mm diameter retaining clip for securing the insulation to the inner masonry leaf shall be used in conjunction with the above.

5.8.3 Slip Ties

At vertical movement joints, slip ties such as the ‘PPS’ stainless steel wall tie with debonding sleeve by ‘Ancon’ or similar may be required across the movement joint at 450mm vertical centres depending on the type of building, anticipated wind loading and the height of the wall. The debonding sleeve must be pulled back by at least 10mm prior to installation to allow for expansion as well as contraction of the brickwork.

Slip ties shall be provided where detailed by the Structural Engineer.

6.1 INTERNAL WALLS & PARTITIONS 6.2 Partitions – (General)

All partitions shall be constructed to provide an acoustic performance based on laboratory values for airborne sound insulation of 40Rw dB.

Gypsum wallboard can be used in wet rooms to receive ceramic wall tiling in localised areas such as splash-backs behind kitchen sinks and wash hand basins. In other areas where splashing of water is likely, such as around baths and showers, moisture resistant plasterboard shall be used in accordance with BS 8212 : 1995 and/or the manufacturers recommendations.

Plasterboard shall be cut 15mm shorter than the floor to ceiling height and positioned tight against the ceiling using a ‘footlifter’. Packers are to be inserted at floor level until the adhesive has set. A gap of at least 5mm shall be left between the bottom edge of the skirting and the top of the screed or concrete floor finish which shall be sealed with a flexible sealant.

All joints shall be properly sealed to prevent loss of acoustic performance through air paths.

6.2.2 Non Load-bearing Timber stud Partitions 75x50mm softwood studding with both sides finished with 15mm “Gypsum SoundBloc” plasterboard by ‘British Gypsum’, minimum mass 10.5kg/m

2

, or similar, providing 30 minutes fire resistance.

Finished with either, taped and filled joints or taped joints and 3mm plaster skim finish.

75mm thick mineral wool to be inserted between studs within partitions.

Additional studs and noggings are to be provided as necessary for sanitaryware and kitchen unit support, etc. Where wall tiling is proposed it may be necessary to reduce the centres of the studs to 400mm c/c, refer to manufacturer’s details.

6.2.3 Ducting

Soil pipes passing through ALL rooms to be lagged with minimum 25mm sound deadening insulation quilt (unfaced with a minimum density of 10kg/m3), fixed to prevent settlement or slippage. 2 layers 12.5mm plasterboard screw fixed to timber framing.

6.2.4 Bustressing Long external walls may need to be provided with intermediate buttressing walls or partitions (refer to details) designed for the purpose, where in doubt check with structural engineer.

6.2.5 Codes of Practice and BS EN Standards

BS 8000 Pt8: Workmanship plasterboard partitions and dry linings

6.2 Party Separating Walls As Robust Detail E-WM-14

302mm wall to consist of 2No. leaves of 100mm Hemelite standard lightweight aggregate blocks (density 1350 to 1600kg/m³ – 3.5 N/mm² as shown on drawings or similar approved with 100mm cavity. Provide partial fill to the cavity using 35mm Isover RD35 foil faced mineral wool acoustic batt (foil facing the cavity). All masonry joints to be filled full depth with continuous mortar with 12.5mm British Gypsum wallboard ten (Min. 9.8kg/m²) on dabs both sides. All joints taped and filled.

Mortar mix to be 1:4½ cement : sand or 1:3 cement : sand dependant on brick type and exposure. Refer to NHBC standards Appendix 6.1D.

Masonry leaves connected by Ancon HRT4 wall ties or approved similar at maximum 750mm horizontal and 450mm vertical centres to B.S. 1243 and section 2 paragraph 2.19 (Type A) of Approved Document E (2003).

Inner leaf of external cavity wall to be butted against party wall and secured with ties at every block course. Cavity at junction of party and external wall is to be closed with a flexible cavity closer such as mineral wool or other equal approved product and vertical DPC. Where large staggers occur, the separating wall blockwork must continue for 300mm min beyond the stagger point before reverting to the inner leaf blockwork (see Part E Robust details Appendix A). Party wall is to be taken up to the underside of the roofing felt and fire stopped with minimum 50mm reinforced mineral wool in accordance with Building Regulations and NHBC standards.

Refer also to Accredited Detail MCI-IW-01 & 02.

7.1 INTERMEDIATE FLOORS AND CEILINGS 7.2 Floors - (General)

All floors within single occupancy dwellings shall be constructed to provide an acoustic performance based on laboratory values for airborne sound insulation of 40Rw dB.

Refer to manufacturer’s specification, drawings, calculations and third party accreditation for upper floor engineered timber I-beam floor joist layouts and pcc floor designs.

Floors must not be loaded with building materials such as bricks, blocks or mortar tubs, etc, unless the floor (and hangers where appropriate) have been specifically designed to support such loads by a Structural Engineer.

7.1.1 Timber Floors - (Housing)

22mm ‘Weyroc Protec’ or similar protected T&G chipboard flooring, minimum mass 15kg/m2, laid with cross joints staggered, glued and screwed to timber I-beams. Temporary I-beam bracing will be required during the fixing of the floor boards.

Ensure that short ends and all perimeter boards are fully supported, laid with a 10mm minimum expansion gap around the perimeter. Prior to laying the perimeter board, protective tape must be folded over the exposed edge. Exposed faces / cut ends to be painted as per manufacturer’s details.

Timber I-beams shall be set-out at 600mm maximum centres, sized specifically for the identified load and span. Flange widths shall be at least 45mm to accommodate secure fixing of plasterboard. All strutting, trimming and infill blocking shall be in accordance with manufacturer’s details. The I-beam flanges are not to be cut to accommodate any services

or anchor straps. Such holes are to be sized and located within the I-beam web at centres specified by the manufacturer. Refer to Technical Manual.

I-beams may be built in to the inner leaf of the cavity wall providing that filler pieces of ply or similar approved material are fixed to both sides of the web at the end of the I-beams where they are to be built in, ensuring that a gap is left between the filler pieces and both the top and bottom flanges for timber expansion. Proprietary foam joist end stops to be used for joist ends built into masonry. Stop ends installed in accordance with manufacturers recommendations

Lateral support at floor levels shall be provided in accordance with Approved Document Part A 30x5mm galvanized m/s anchor straps at 2000mm maximum centres to all intermediate floors shall be provided at right angles to and carried past the first three I-beams. Beneath the straps provide 38mm minimum solid timber noggings, extending at least half the depth of the I-beam. Refer to Structural Engineer’s design.

Evidence of Part E compliance must be sought from the I-beam manufacturer. Generally the major manufacturers have independent accreditation to satisfy Building Control that the following floor construction is compliant:

22mm T&G chipboard flooring, minimum mass 15kg/m2, typically on 241mm I-beam with 15mm “Gyproc Wallboard”, by ‘British Gypsum’ or similar plasterboard, minimum mass 10kg/m2, screw fixed to the I-beams, (refer to manufacturers details for noggins) with 3mm skim finish.

In addition to the above specification, reference must be made to the specific plasterboard/I- beam manufacturers details.

Downlighters in ceilings providing of up to 30 minutes fire resistance will generally have

apertures no greater than 85mm diameter, spaced at 900mm minimum centres and no closer than 300mm from the edge of the board. Refer to I-beam manufacturer’s fire certification.

7.3 Services:

Reference should be made to the CORGI Technical Bulletin 217 for installation of gas pipes within floor voids (design Pages within OnSite). Alternatively they can be laid in a screed (refer to clause 6) and where they rise vertically in apartments they should be housed within ventilated ducts (ventilated at each storey height) or a riser (where this is ventilated to the outside) in accordance with Corgi requirements. Where they rise vertically behind plasterboard on a masonry wall they should be surrounded in continuous gypsum based adhesive bead.

Space and water heating pipework and electrical cables may be run in the ceiling void to a separating floor provided they are adequately clipped to the floor unit soffit.

Service pipes may be incorporated into the floor voids of intermediate floors by feeding through the perforated knockout holes or by passing through site-drilled holes strictly in accordance with the manufacturers permitted zones. The flanges must NOT be drilled, notched, or otherwise altered on site.

Where boilers are positioned centrally within the property and not on external walls such as apartments the flue must be accessible for visual inspection along its route. Full guidance on this can be found on the CORGI Technical Bulletin 200 “Room- sealed fanned draught flue systems concealed within voids”. General notes are as follows:

It is not intended to that additional provision for inspection should be provided for short flue sections passing directly through an external wall.

Open flues are not covered by this bulletin and separate guidance should be sought. It is necessary for means of access to be provided at strategic locations so that the flue system can be visually inspected along its route. The means of access should allow for visual inspection to be achieved for the entire length of the flue system, including any separately routed air supply pipe, particularly where there are deviations or joints and supports. It is not envisaged that means of access is provided at every joint, deviation or support but that it can be visually inspected in some way.

The access provided needs to be sufficiently sized to allow a visual inspection. It is not intended to allow physical access to the flue system for example to carry out maintenance.

Location of the means of access should be decided upon through liaison with the CORGI registered business installing the flue system.

7.4 Codes of Practice and BS EN Standards

BS 8103 Structural design of low rise buildings: Pt4 Code of Practice for suspended

concrete floors for housing

BS 8110 pt 1: Design and manufacture of pc units and concrete mix proportions to satisfy Table 3.4 with the use of additives to BS 5075

BS 8000 Pt5: Workmanship carpentry, joinery and general fixings

8.1 JOINERY 8.2 Doors – (General)

The provision of Fire Safety shall be in accordance with Approved Document Part B, Resistance to the Passage of Sound with Part E and Access and Facilities for the Disabled with Part M of the Building Regulations.

8.2.1 External Doors

44mm external doors to be steel faced, insulated and weather-sealed, having a minimum 775mm clear opening and accessible threshold. Frame to be s/w with composite cill, including an adjustable Part M compliant threshold strip.

8.2.2 Internal Doors

Internal doors to habitable rooms (as defined by Approved Document Part M) on the entrance or principle storey shall have minimum clear opening width of 775mm.

Corridors shall have a minimum clear width of 900mm when approached head on or 1050mm clear width when not approached head on.

WC compartments and bathrooms in apartments shall be provided on the entrance or principle storey and have outward opening doors.

8.2 Windows – (General)

Provide standard double glazed (BS 5713) draught sealed timber/PVCu windows Windows shall provide rapid ventilation in habitable rooms to at least 1/20th floor area, part of which being 1750mm above floor.

Trickle vents to be provided as detailed in Section 11.0 of this document. Glazing in critical

Locations shall be as detailed in Approved Document Part N. Below 800mm measured from floor level for glazed screens and windows. Below 1500mm measured from floor level for doors and any side panels within 300mm of the door.

Glazing in these areas shall be toughened safety glass to BS 6262 : Part 4.

Egress windows to be provided in accordance with Approved Document B.

Such windows shall have a minimum unobstructed opening area of 0.33m2, provided by an opening of at least 450mm high and 450mm wide, with the lowest part of the opening located no higher than 1100mm above floor level. Egress hinges to have restrictors with emergency override.

Window cills shall have an anti-capillary drip and project beyond the external face of the wall or any sub cill by at least 25mm.

The frame must be located in the reveal so that there is a 30mm minimum overlap with the cavity closer to reduce the effect of cold bridging around openings.

Windows and glazed doors shall provide a maximum 'U' value of 2.0W/m²K. This U-value is an area weighted value and is applicable only where the total area of doors; windows and roof-lights does not exceed 25% of the total floor area.

Consider the CDM Regulations 2007 regarding access to windows and the arrangement of

opening lights, so that safe access for cleaning is possible, especially those windows serving the 3rd storey and above of both houses and apartments.

Obscured glass shall be ‘Chantilly’ pattern and be provided in windows to Bathrooms, WC’s and En-suites, together with front entrance doors and side screens where non-decorative obscured glazing is specified and external doors to utility rooms. The Chantilly glass will form the inner pane of the sealed double-glazed unit. It is not necessary for kitchen doors to be fitted with obscured glazing unless there is a privacy issue on a side elevation. Front doors will not have obscured glazing.

8.2.1 PVCu Windows

All PVCu windows to be manufactured to BS 7412.

All windows to have sealed, double glazed units with 4mm panes, the inner being low- emissivity with an air gap of at least 16mm, fixed with glazing beads and tape.

All glazing to comply with BS 7513.

The windows shall be packed square and fixed with galvanised metal straps to the internal leaf. The straps are to be located within 150mm of the top and bottom edges at the jamb and at 450mm max centres thereafter, those frames over 1500mm wide shall have additional head and cill fixings.

5mm tolerance gap shall be left between the window and the facing brickwork which shall be sealed with a low modulus silicone sealant to BS 5889.

Where expandable foam filler is used between the window frame and masonry opening avoid injecting excessive amounts as this may deflect the jambs and induce vertical bow.

8.2 .3 Glazing

Factory glazed 24mm glass units. Obscure glazing to all rooms containing sanitary fittings. Toughened glass to locations required to meet with Building Regulations ADM. The thermal transmittance value to be not less than 1.8w/m2K or 1.5 w/m2K ‘B’ rated for a typical sized window dependant on wall specification.

Manufacturer to confirm compliance with the ‘U’ value and rating.

Rooflights: The thermal transmittance value to be not less than 1.5 W/m2K for a typical sized window to match the remainder of the dwelling.

Each and every glazed unit should have the appropriate BS Kitemark (on the glazing bar) permanently marked.

8.2 .4 Background Ventilation

For system 1 of ADF (background ventilators and intermittent extract fans) they should be located in all rooms (minimum 5,000mm² equivalent area in all habitable rooms and 2,500mm² in all wet rooms with an external wall). The total equivalent area should be at least that given in Table 1.2a of the Approved Document. Background ventilators should be at least 0.5m from the extract fan and located to avoid draughts (typically 1.7m above floor level). To maximise the air-flow through cross ventilation it is best to locate similar equivalent areas of background ventilators on opposite (or adjacent) facades of the dwelling. See Table 1.2a for single façade dwelling requirements.

Min performance to BS EN 13141-1 clause 4

Equivalent areas “marked” on the product in an easily visible location

For rooms with no external wall and ventilation through another room follow the guidance in ADF

In noisy areas it may be necessary to use either sound attenuating background ventilators or mechanical ventilation solutions depending on the noise level and any planning conditions. Manufactures are required to provide options to these situations as requested.

Manufacturers are required to produce the appropriate background ventilation table for compliance with the Building Regulations.

For a system 3 approach of ADF (Decentralised MEV or MEV) background ventilation may not be required and could be dependent on the air permeability of the dwelling. It is therefore recommended that as a precaution background ventilator (trickle vents) be provided to each room with an equivalent are of 2500mm2 except for wet rooms from which air is extracted. Manufacturers to be contacted for their recommendations on their particular system.

8.2 .5 Purge Ventilation

Purge ventilation is required in each habitable room (openable window) and be capable of extracting a minimum of four air changes per hour per room directly to the outside.

In a habitable room not containing openable windows the requirement will be met if the room is either ventilated through another habitable room or through a conservatory provided there is provision in that room for both (see diagrams 2 & 3 of ADF)

For a hinged or pivot window that opens 30 degrees or more or for sliding sash windows the height x width of the opening part should be at least 1/20th of the floor area of the room. This criteria equally applies to external and patio doors – refer to manufactures schedule of opening sizes.

8.2 .6 Ironmongery & Security

Opening lights to be hung on stainless steel friction hinges concealed in frame rebates giving easy clean facility (min 95mm between frame and casement). They are to have multi-point espagnolette locking head system with mushroom head bolts for high security.

Die-cast handles with cylinder locking (except to escape windows) are to be factory

fitted as see appendix for options.

Windows shall conform to NHBC security requirements and where requested by the regions be produced to the “Enhanced Security” requirements of the British Standard.

8.2.7 Codes of Practice and BS EN Standards

BS 7412 / 7413 - Manufacturing compliance

BBA Certification or Kitemarking to BS

BS EN 1279:2002 - Specification for hermetically sealed flat double glazed units and BS 6262 1982

BS 7950: Enhanced security (when specifically requested)

BS 6375: Air permeability 600 Pa. Water tightness 300 Pa. Wind resistance 200Pa.

BS EN 1670: Class 4: Corrosion resistance.

BS 5925 – Ventilation principles and designing for natural ventilation

9.1 STAIRS, STEPS, RAMPS AND GUARDING 9.2 Stairs and Guarding – (General)

Staircase design must comply with Approved Documents Part K and Part M of the current Building Regulations, with guarding capable of resisting at least the horizontal force given in BS 6399 : Part 1 : 1996. A gap no greater than 99mm shall be provided between vertical balusters, however, where glazing is used in the guarding, it must also comply with Approved Document Part N.

Guarding to balconies shall be 1100mm high measured from floor level.

2000mm minimum clear headroom shall be provided, measured vertically from the pitch line of the stairs.

The staircase design will be dependant upon the overall finished floor-to-floor height and depth of structural floor adopted, refer to individual floor layouts for accurate staircase configurations.

9.2.1 Private Stair

Pitch shall not to exceed 42˚. Maximum rise 220mm, and minimum going of 220mm. The minimum clear width of the flight shall be 885 or 985mm, with a continuous handrail provided to one side of the stair where the flight comprises three or more steps. Double newels at winder locations are not permitted. Handrails should be between 900 and 1000mm high and balusters spaced so as not to allow a 100mm sphere to pass through at any point

For stairs having between one and four tapered treads/winders in a flight about a ‘single’ newel, providing the newel provides a safe handhold, a handrail is not required to the outside of the stairs.

For stairs having a pair of winders consisting of between one and four tapered treads or quarter landings separated by a flight between a pair of ‘single’ newels, providing the newels offer a safe handhold, a handrail is not required to the outside of the stair.

A handrail is required to the outside of a stair, where for example, a stair has a full winder set around a ‘double’ newel that is too large to be considered as offering a safe handhold. (See NHBC consistency matters – Hand hold fully interrupted)

The handrail to the outside of the stair must be continuous for the whole rise to avoid the need to change hands.

9.2.2 Codes of Practice and BS EN Standards

BS 585: Wood stairs. Specification for performance requirements for domestic stairs constructed of wood-based materials

10.1 ROOF CONSTRUCTION 10.2 Roof Structure – (General)

Structural design and calculations shall be submitted to Building Control prior to commencement of the roof construction on site.

Dead and imposed loads should be calculated in accordance with the British Standard. Structural timber should be specified according to strength classes of the British Standard in conjunction with Approved Document A of the Building Regulations. Wind loads appropriate to the site location should be calculated in accordance with the British Standard and the roof designed to resist wind uplift, holding down straps should be utilised where the self weight of the roof is not sufficient – Check with the local building control body.

For low pitches below tile manufacturer’s recommendations, a proprietary (Ondutile or equal) sarking system may be utilised provided the BBA Certification and manufacturers installation guidance is followed.

ROOF TYPE U VALUE

Insulation at ceiling level) 0.17

Insulation follows roofline (Family room) 0.22 10.2.1 Cut Roof

Provide s/w timber rafters positioned at 600mm maximum centres supported off s/w wallplates and structural ridge to Structural Engineers design/calculations, continued down and ‘birdsmouthed’ over timber purlins as detailed.

Timber to be SC3 grade unless otherwise noted.

10.2 Tiling – (General)

All roof tiles to be fixed in accordance with manufacturers recommendations. Nailing specification to be site specific and will be required for each house type from manufacturer and is to be available on site.

10.2.3 Interlocking concrete Tiles

Roof tiles to be fixed in accordance with manufacturers recommendations and BS 5534 : 1978, colour and profile to Local Authority approval on 38 x 25mm treated s/w battens for rafters at 600mm centres with bedded ridge and hips tiles, Verges to be pointed in 1:3 mortar.

10.3 Insulation – (General)

The ‘U’-values shown for the constructions below are based on an Elemental ‘U’-value, whereas normal practice would be to consider the thermal efficiency of the building as a whole. Our recommendation is that some adjustments to the levels of insulation to the roof and ground floor may be realised by adopting the Target ‘U’-value method of demonstrating compliance.

10.3.1 Cold Roof – Pitched

Roof tiling, on battens, on ‘Type 1F’ sarking felt to BS 747, on timber rafters with 38 x 100mm (assumed) ceiling ties at 600mm centres, 300mm thick ‘Crown wool’ glass mineral wool insulation, thermal conductivity 0.044W/mK, by ‘Knauf Insulations’ or equal approved laid in two layers, 100mm between the ceiling ties with 170mm cross laid above ceiling ties to avoid

cold bridging effects.

This construction will achieve an Elemental U-value of 0.16W/m2

K.

10.3.2 Cold Roof – Ventilation

Continuous ventilation shall be provided to the full length of eaves (or low level at valley situations), with either a proprietary over-the-facia or soffit strip, with integral insect mesh, to avoid condensation within the roof space.

For roof pitches below 15˚ (flat roofs) a ventilation area equivalent to a 25mm continuous gap shall be provided, whereas a 10mm gap is sufficient for roof pitches greater than 15˚.

Proprietary insulation restraints at eaves level shall be provided between the trusses giving a 25mm minimum ventilation gap over.

Where spans are more than 10m or the pitch is more than 35˚, additional ventilation equivalent to a 5mm continuous gap shall be provided at the ridge.

Where mono-pitch roofs cannot be cross ventilated, ventilation equivalent to a 5mm continuous

gap shall be provided at high level in the form of a proprietary ventilator.

10.3.3 Warm Roof – Pitched, Room-in-Roof

100mm Kingspan TP10 friction fixed between rafters 20 mm min space to be provided between tile battens and upper surface of insulation to allow the breather membrane to drape. Install 25mm Kingspan K18 insulation underdrawn with 12.5mm plasterboard

Joints to be taped, with a 3mm skim coat plaster finish.

This construction should achieve an Elemental U-value of 0.20W/m2

K.

10.3.4 Warm Roof - Ventilation for Vapour Permeable Membrane

Where vapour permeable membrane is to be used, the insulation will generally fully fill the space between the sloping rafters, the roof space is unventilated and the ceiling insulation is generally pushed up tight against membrane. 50mm minimum ventilation gap above the membrane shall be provided by treated counter battens fixed directly to the rafters through the membrane or other such suitable method to ensure ventilation gap is maintained.

At the eaves a 25mm minimum ventilation gap with insect mesh and additional ventilation equivalent to a 5mm continuous gap at high level or at the ridge shall be provided.

10.3.5 Warm Roof – Ventilation for Sarking Felt

Where an impermeable, high vapour resistance sarking felt is used, a 50mm ventilated air path is required between the sarking felt and the insulation fixed between the rafters to ensure cross ventilation of the roof.

At the eaves a 25mm minimum ventilation gap with insect mesh and additional ventilation equivalent to a 5mm continuous gap at high level or at the ridge shall be provided.

10.4 Roofing underlay – (General)

The detailing and installation of the membrane and ventilation must be in accordance with the specific manufacturer’s recommendations and third-party accreditation.

10.4.1 Untearable Sarking Felt

Untearable roofing felt to be in accordance with BS 747 (1f) laid over rafters with a 150mm horizontal lap and 100mm vertically, carried into gutters and secured with clout nails, to be cut and dressed around penetrations in accordance with CP 144 Part 3. 5u felt to eaves DPC non-degradeable

10.4.2 Gas permeable Sarking Membrane

Where a gas permeable sarking membrane is used, the vapour resistance must not exceed 0.25MN.s/g in accordance with BS 5250 : 1989 (1995). The application must be in accordance with the specific manufacturer’s recommendations and third-party accreditation. Generally the membrane shall be draped over rafters in horizontal runs, with a horizontal lap between 150/225mm; vertically a 100mm lap is required to coincide with the rafters. The membrane shall be laid over a proprietary UV-resistant eaves strip Type 5u and secured with clout nails to the rafters. The membrane shall be cut and dressed around penetrations in accordance with CP 144 Part 3.

10.5 Roof Sundries – (General)

Insulated roof access hatches to be secured in place and draught proofed, in accordance with Part L1 Clause 1.25D. Where installed within a protected staircase they should provide min 30 minutes fire protection.

10.5.1 Metalwork

Lateral support at roof level shall be provided in accordance with Approved Document Part A

Provide 30x5mm galvanised m/s restraint straps (complying with CP111) to pitched, gable roofs, taken over the timber rafters at 2000mm maximum centres at gable end and separating wall locations, lapped over and secured to the blockwork inner leaf within the cavity and fixed to the first three rafters adjacent to the gable wall. Softwood noggins fixed between the gable wall and first three rafters for strap fixing, in accordance with BS 5268 : Part 3 :1985. Additional straps may also be required at the gable or separating walls fixed to the top of the first 3 ceiling ties immediately adjacent to the wall, refer to Structural Engineers design.

Trusses to be fixed to the plate with truss clips. Where trusses are to be hung, especially if little or no blockwork is to be built above, the ‘Masonry Independent Hanger’ from ‘Marlows’ for SWL up to 8kN should be used.

10.5.2 Valleys

Valleys to be formed using third party accredited, proprietary, UV resistant GRP or ABS valley liners providing a 125mm wide clear water channel. The valley trough shall incorporate resin-bonded silica sand mortar grips and integral water slew prevention bars that allow the use of the valley trough with differing adjacent roof pitches. Valley trough must be lapped by at least 150mm and fully supported with 12mm wbp ply layboards fixed between the rafters on 38 x 50mm noggin supports at 600mm maximum centres.

All fixed and weathered in strict accordance with manufacturers recommendations.

10.5.3 Facia and Barge

White extruded PVCu, style and sizes to be site specific.

Facia and barge are 16mm thick and self supporting; this product requires no backing of timber. Fixings shall be white “Polytop” stainless steel nails, 2 no. fixings at 600mm minimum

centres, with low modulus silicone sealant to joints and corners.

Soffits with proprietary vent strips are available providing either a 10 or 25mm vent.

Joints in soffits are made with ‘H’ trims and fixed as the facia and barge.

Within enclosed eaves, at the junction with the separating wall, the void is to be fire stopped to maintain fire separation between occupancy’s with a mineral wool quilt or fire resistant board that will provide fire and smoke separation fixed to the adjacent rafters.

Refer to NHBC Standards, Chapter 7.2 – D13.

10.5.4 Ceilings – Roof Level

The main roof ceiling shall be 12.5mm plasterboard screw fixed to ceiling joists/ties, with 38 x 38mm noggins provided to support board edges and around the perimeter. Where the minimum fixing tolerance, (typically 38mm), for butting plasterboard given by the

plasterboard manufacturer cannot be met by the width of the ceiling tie, 50x25mm battens should be screw fixed to one side of the ceiling tie in order to extend the bearing surface.

Where vapour control is required, reference should be made to BS 5250 regarding the need for vapour checks and their positioning, “Gyproc Wallboard Duplex”, by ‘British Gypsum’ or similar approved plasterboard backed with a vapour control membrane may be used. Noggings are generally required regardless of joist spacing and board thickness in order to ensure that all joints are fully supported and that the integrity of the vapour control layer is maintained.

Plasterboard joints shall be taped with a 3mm skim coat plaster finish.

Downlighters in ceilings providing of up to 30 minutes fire resistance will generally have apertures no greater than 85mm diameter, spaced at 900mm minimum centres and no closer than 300mm from the edge of the board. Consider the effect of such penetrations in the ceiling and refer to the plasterboard manufacturer’s fire certification. An air gap shall be provided around recessed downlighters by localised areas of ply fixed over the ceiling ties above the fittings to prevent the insulation within the roof from laying directly on the fitting. This air gap reduces the potential for the fittings overheating.

10.6 Codes of Practice and BS EN Standards

BS 6399: Roof loading

BS 5268 Pt2 Structural timber design

BS 5268 Pt3: Roof truss design

BS 6399 Pt2: Wind loading

BS 402: Clay tiles

EN 490 /491 Concrete tiles

BS 5534: Code of practice for slating and tiling

BS 747: Underlay

BS 5250 Code of basic data for the design of buildings: The control of condensation in dwellings

BRE Thermal Insulation: Avoiding the risks

11.1 VENTILATION 11.2 General

Ventilation shall be in accordance with Approved Document Part F. Ducting for mechanical ventilation shall be ‘flat-duct,’ sized appropriately by ‘Domus’ or similar. Alternatively, for housing, the ‘flat-duct’ may also be run on top of kitchen/utility wall units to an air brick terminal. For bathrooms, the extract fan shall be ceiling mounted and connected to an insulated vertical duct to proprietary ridge or vent tile. Where this is impractical the duct shall be run horizontally in the floorzone to an air brick adaptor.

Habitable Rooms:

Rapid ventilation: -Opening windows minimum 1/20th of floor area Background ventilation: - 8000mm

2

(trickle ventilation)

Kitchens:

Rapid ventilation: -Opening window (no minimum size) Background ventilation: -4000mm²

(trickle ventilation) Extract ventilation: -Mechanical ventilation 60 litres/second or

30 litres/second when incorporated in cooker hood.

Utilities: Rapid ventilation: -Opening window (no minimum size). Background ventilation: -4000mm

2

(e.g. trickle ventilation). Extract ventilation: -Mechanical ventilation 30 litres/second intermittently.

Bathrooms:

Rapid ventilation: -Opening window (no minimum size) Background ventilation: -4000mm

2

(e.g. trickle ventilation) Extract ventilation: -Mechanical ventilation at 15 litres/second intermittently

Sanitary Accommodation:

Rapid ventilation: - Mechanical ventilation at 6 litres/second intermittently.

Background ventilation: - 4000mm2

(e.g. trickle ventilation) Where kitchens, utilities, bathrooms and sanitary accommodation do not contain an openable window, mechanical extract shall be activated by the light switch and have a 15minute over-run.

12.1 SERVICES 12.1.1 Electric

The location of the wall mounted metres shall be located in discrete, but accessible locations, where possible within 2m of the consumer unit for housing and generally housed under the stairs at ground floor level or in a purpose built cupboard close to the service riser.

The installer shall be an approved NICEIC contractor and all installations shall be in accordance with IEE Regulations - BS 7671.

Cables may need to de-rate where covered or surrounded by thermal insulation. Guidance is available in the BRE Report ‘Thermal insulation: avoiding risks’. PVC covered cables should not touch polystyrene insulation.

British Standards relevant to design of electrical installations and appliances include BS 3456 and BS 3955.

12.1.2 Gas

Semi concealed meter boxes are to be located in discrete, but accessible locations.

The supply pipe-work to apartments shall generally be run internally within vented ducts in accordance with BS 6891 : 1998. Alternatively, they may be routed externally concealed within a dummy rwp. All gas installations shall be carried out by a CORGI approved installer.

In addition to the duct specification above, ducts containing gas pipes in apartments shall be ventilated at the top of the duct to external air at each floor level (between separating floors) in accordance with Gas safety regulations (SI. 1972/1178) & (SI. 1984/1358); Institute of Gas Engineers publication IGE/TD/4 and BS 6891 : 1998.

Horizontal and vertical ducts containing gas pipes with a cross sectional area of 0.01m2

or less and a volume of 0.1m

3

do not require ventilation.

Consider the routing of copper gas supply pipes where run behind plasterboard to reduce the risk of puncture damage from purchaser’s fixings. Where the pipes are considered at risk, galvanised steel protection plates over the pipework shall be provided.

12.1.3 Telecom

Ducts are to be provided from the highway to the property and hard wiring within the dwelling from the main connection box to the outlets in rooms as specified.

12.1.4 Cable/Satellite

Where cable is available, ducts are to be provided from the highway to the property with hard wiring within the dwelling from the main connection box to the outlets.

Consider the location of any communal aerial or dish and any booster equipment in apartments where cable is unavailable.

12.2 Heating and Domestic Hot Water – (General)

The Elemental Method of demonstrating Part L1compliance can only be used when the Mains Natural Gas boiler has a minimum ‘SEDBUK’ rating of 78%, (SEDBUK - Seasonal

Efficiency of a Domestic Boiler in the UK, defined in the Government’s Standard Assessment Procedure for the energy rating of Dwellings).

The Elemental Method of demonstrating Part L1compliance cannot be used where direct electric heating is proposed.

Heating and domestic hot water systems shall be inspected at completion of installation in order to establish the specified and approved provisions for efficient operation have been put into place.

A suitable commissioning certificate is required, published as part of the Benchmark Code of Practice for the installation, commissioning and servicing of central heating systems administered by the Central Heating Information Council.

A suitable set of operating and maintenance instructions in an accessible format in each new dwelling, to enable the owner/occupier to correctly operate and maintain the heating and hot water system.

Provide insulation to ducts and pipes to conserve heat and help maintain the temperature of the water, to current Building Regulations Approved Document L1, Clause 1.52 and 1.53. The heating system shall be designed in accordance with NHBC Standards, Chapter 8.1

Insulate pipe work up to 1m from cylinder or until pipes are concealed.

12.3 Gas - Heating and Domestic Hot Water – (General)

Central heating and domestic hot water will generally be provided by room sealed gas fired boiler, (combi boiler where appropriate) with controlling timer and boiler control interlock.

Balanced fanned flues shall be used as appropriate with the location of boilers within apartments considered at the design stage to ensure that the flue runs can be accommodated for distance and falls.

Separate timing controls shall be provided for space heating and water heating.

Temperatures within sleeping and living areas shall be controlled independently with a room thermostat, generally located within the Hall and thermostatic radiator valves on all radiators except the Hall radiator.

Long water main runs shall be increased to 35mm to maintain adequate flow rates.

Where water main pressure is 5bar and over, pressure reducing valves may be required.

Proprietary lime scale reducers are recommended in hard water areas.

Where condensing boilers are integral to the combined primary storage units, the location of the unit within the dwelling must consider the fall of the flue, generally 50mm in every metre for straight runs, which must be catered for within the ceiling void. Refer to manufacturers details.

The system shall consist of a gas boiler heating the primary water for dwellings up to 6 beds. Generally the mains feed will be 25mm at a minimum of 1bar, however for the largest boiler size a 35mm main supply and minimum 2bar pressure is required.

Storage capacity of the insulated thermal store range from 125 to 225 litres capable of providing 35litres/minute of domestic hot water raised through 35 degC directly from the mains.

A room thermostat, thermostatic radiator valves and an integral programmable timer are to be incorporated in the system to control the primary circuit as required by Approved Document

Part L1.

A separate feed and expansion tank is required located at a height above the boiler as specified by the manufacturer.

The system can be used in conjunction with under floor central heating however where plastic plumbing is proposed a mixing valve may be required to lower the temperature of the primary circuit, check manufacturer’s recommendations.

Consideration must be given to the locating the appliance within a separate cupboard to the area dedicated for lined storage due to the size of appliance.

The primary system shall be cleansed and filled with a scale/corrosion inhibitor as Manufacturers recommendations.

Emergency back-up ‘Switch’ may be provided as an addition to the system by the inclusion of an in-line 9kW electric heating element that provides both heating and hot water in the event of the failure of the gas boiler.

The ‘Switch’ requires a 10mm cable and 45Amp supply from the consumer unit. Check with manufacturer’s recommendations and design for preferred location of switching.

12.4 Plastic Plumbing

The system must be accredited and be designed and installed in strict accordance with the manufacturer’s instructions using appropriately sized ‘standard’ and ‘barrier’ pipe as applicable.

Pipe runs shall be designed to minimise the number of fittings, manifolds may be considered however a cost balance must be made between the use of excessive length of pipe and fittings. Pipe and fittings used on any particular dwelling must always be from one manufacturer product line, never mix fittings or pipe.

The plumber must ensure that the pipe is cut with an approved cutter, the correct pipe inserts are fitted and that the connections are properly made.

The system shall be pressure tested after first fix with proprietary air or water test apparatus for between 15 to 60 minutes at a pressure recommended by the manufacturer, typically this will be between 12 to 18 bar. After second fix it is recommended that a further test is undertaken to ensure the system is without leaks.

Insulation shall be fitted to pipe-work as required by Approved Document Part L1.

The systems shall have drain points and all supplies to appliances shall be fitted with suitable isolation valves. The flow and return connections at the boiler shall be made in 22mm copper, the first plastic connection can be no closer than 1m to the boiler.

Exposed pipe-work within kitchen/utility base units, airing cupboards and radiator tails shall be either rigid white plastic or painted copper with ‘yorkshire’ type potable integral lead-free solder ring fittings.

Pipes shall be restrained by proprietary clips at centres recommended by the manufacturer; the pipework shall be run vertically or horizontally within partitions,

Radiator tails are to pass through a proprietary outlet plate in the partition or wall, positioned centrally behind the radiator. The white plastic tails are to be fitted to compatible ‘push-fit’ elbow radiator valves. Where practical, pipes should not be laid in the screed of separating floors, but run in the suspended ceiling void and dropped behind the plasterboard to the proprietary outlet plates behind radiators. Plastic pipework with the structure to have a means of location by metal detector as per NHBC recommendations.

12.4 Codes of Practice and BS EN Standards

BS 4576: Unplasticized polyvinyl chloride (PVC-U) rainwater goods and accessories.

Half-round gutters and pipes of circular cross-section

BS 5955 Pt 8: Specification for the installation of thermoplastic pipes and associated fittings

BS 5449 Pt1 & EN 442: Central heating for domestic premises

BS 7206: Specification for un-vented hot water storage units and packages

BS1566: Copper indirect cylinders for domestic purposes. Open vented copper

cylinders. Requirements and test methods

BS 8000 Pt13: Workmanship above ground drainage and sanitary appliances

BS 8000 Pt15: Workmanship hot and cold water services

BS 6891: Specification for installation of low pressure gas pipework of up to 28mm in domestic premises

12.5 Electrics and Lighting – (General)

Electrical services shall be designed and installed in accordance with the latest amendments of the NICEIC and IEE regulations for the safety of electrical installations for buildings, IEE

Wiring Regulations (BS 7671).

Socket outlets which might reasonably be used for external appliances should be protected by a residual current device (RCD).

12.5.1 Meter Box Connection

Where the site is “self connect” i.e. the electrical contractor makes the connection from the consumer unit to the meter, this is normally to switch fuse in the meter cupboard, in which case there should not be a restriction on the “tails” between the meter box and cu positions. Where the electricity utility provider makes the connection, they will normally insist on a maximum distance of approx 2m between the two unless a separate switch fuse is provided which they will not normally allow to be positioned in the meter box. Therefore the designer should be aware of the implications and avoid situations where the meter box and cu are remote.

12.5.2 Electrical Points, Lighting and Extract Fans The resistance of ducted systems should be matched against the selected fan performance curve (available from the manufacturer) to achieve the installed performance for the room. Where a duct rises vertically a condensation trap shall be fitted. Ensure flexible ducting is installed without peaks or troughs.

Kitchen extract vent – not less than 30 litres/second when incorporated into a cooker hood. 60 litres/second where located separately in an external wall or ceiling. Ducting to be rigid over wall units or flexible in floor voids (or within dropped ceiling to apartments - only permitted in ceiling void if fitted with appropriate fire damper) but the design and length should not impede these performance levels – if in doubt check with fan manufacturer.

Bathroom and en-suite extract vent – not less than 15 litres/second in a wall or within dropped ceiling. 1 gang switch plate with 3 module aperture to feed light switch / double pole fan switch / 3amp fuse for fan.

Cloakrooms, utilities and bathrooms not containing openable windows the extract vent shall be rated as above and operated in conjunction with the light switch with the fan having a 15 minute overrun.

Ensure there is at least a 300mm separation between an extract fan terminal and flue termination of a gas boiler and 500mm between an extract fan and a background (window trickle) ventilator.

To assist those people whose reach is limited and to use the dwelling more easily, light switches, socket outlets and other equipment (not consumer unit) should be located in habitable rooms at appropriate heights between 450 and 1200mm from finished floor level in accordance with Diagram 22 of Approved Document M of the Building Regulations.

Consumer units, fan isolation switches and cooker hood supplies shall be located at high level outside this zone.

Downlighters – to be IP60 (65 above baths and showers) rated limiting air leakage. They must have been designed and tested such that they will not cause overheating when overlain with insulation e.g. low voltage systems with dimmable transformers which can also be changed through the bezel. They should have a 30 minute fire rating in ceilings below roof spaces and 60 minutes in separating floors. They should have been satisfactorily assessed in accordance with the procedure described in Appendix F of ADE Robust Details. A copy of the test report shall be handed to the site manager. They should be spaced at no more than one light per 2m² of ceiling area measured in each room and at ctrs not less than 750mm unless tested otherwise.

Socket outlets to be provided not less than NHBC requirements (8.1 – D11)

Gang switches to be provided within kitchens for all appliances.

12.5.3 Electrical Cables Where cables are concealed within a wall, they should be located at a minimum depth of 50mm from the surface opposite to where the electrical point is positioned – refer to partition manufacturer’s installation guidelines and ensure this is strictly adhered to.

The presence of insulation around a cable has the effect of reducing the current carrying capacity:

Circuits run within thermal insulation must be protected with cartridge fuses or mini circuit breakers (MCBs), rewirable fuses are not suitable.

Cables fully enclosed by insulation may need to be increased in size above the standard recommended by as much as 20% if they pass at right angles through an insulating layer and as much as 50% if they are enclosed along the length for more than 500mm.

For cables enclosed by insulation but in contact with a thermally conductive surface on one side, the larger of the standard recommended sizes will generally need to be used.

Pvc-u Cables should NOT come in contact with polystyrene and where located on walls faced with laminated polystyrene backed plasterboard should be suitably protected.

TV distribution cable to be CT 100 digital satellite / terrestrial.

12.5.4 Energy Efficient Lighting Energy efficient lighting is to be provided in accordance with Approved Document L1A – Fixed energy fittings (light fittings that only take lamps having a luminous efficacy greater than 40 lumens per circuit watt) that the number is not less than the greater of:

One per four fixed lighting fittings (a light fitting may contain one or more lamps).

Kitchens having pelmet fluorescent lighting will comply. The NHBC will accept 2 No bedrooms in lieu of a low energy lighting point in the lounge. LEL is not required in common areas of apartments.

Approved only P18 pendant fittings to be specified generally (B13 and 18 batten holder versions are available). 18 watt Compact Fluorescent Lamps are to be warm white 2700k.

External lighting if provided must also comply if attached to the building. LEL fitting as above or lamp capacity not exceeding 150W and light automatically switches off when there is enough daylight and when not required (time control) at night will comply with the requirement. A wire only specification will not.

12.5.5 Electrical Provision in and around Bathrooms Section 601 of the BS wiring regulations relates to locations containing a bath or shower which are classified into the following zones

ZONE 1 Wraps around and on top of zone 0 and is limited to a height of 2.25m ZONE 2 Reaches 0.6m outside of zone 1 and sits above zones 0 & 1 at a minimum height of 2.25m. Insulation should not cover the fitting as the fitting could overheat, reducing lamp life and creating a fire risk (those installed in ceiling voids to compartment floors should have be 1hr fire rated and meet with RSD’s Appendix F requirements). Extract Fans IPX4 rated (protection against splashing).

ZONE 3 The outer layer is therefore the rest of the bathroom extending to the same height - Shaver Sockets / Batten Holders.

Section 601 defines where 240volt electrical items can and cannot be placed in these rooms in accordance with the zoning. This means fan / lighting positions and wiring accessories unless they are SELV (Safety Extra Low Voltage

Pull Chord/Rocker Switches in wet rooms Are permissible outside this zones Rocker switches preferred and to be located outside the wet rooms.

Fan Isolating Switch Should be outside zone 3 e.g. located 2.25m above this zone or outside the room where the assessment / inspection body permits.

In addition section 601 stipulates that electricity cables in partitions adjacent to zones 0 & 1 need to be a minimum 50mm away from the wall face.

12.5.6 Structured Cabling Where provision is made for 1st and 2nd fix of cabling backbone star wired back to an in- house control box and in substitution of standard TV and BT outlets as indicated on the house / apartment services drawings, these may be “active” or blanked off allowing optional customer upgrade as indicated

TV and Video co-axial cables must be Sky approved (CT100 or H019F) Audio cable must be good quality stranded copper speaker cable (shielded where necessary)

Video Distribution System - should be capable of accepting the optimum number of external inputs such as Satellite, TV, Cable, Door Entry System and CCTV, combining these with a number of internal inputs such as VCR and DVD and allowing for the distribution to any room, the video server should be located in the control panel and installed in a suitable location in the property. The clients video equipment (VCR, DVD and Satellite Digibox may connect into the system via a point in the lounge)

Data Distribution – the system should allow for a 10/100 Ethernet LAN, which will allow data sharing, printer sharing and multiple user internet access, the Data distribution panel and hub is to be sited in the control panel. Live data outlet points to be installed as shown on the drawings.

Voice Distribution system – shall be capable of supporting up to 4 incoming telecom lines that can be routed to any telecom point within the property. The voce distribution panel is to be located within the main control panel. Live data outlet points to be installed as shown on the drawings.

Communal TV and aerial - See separate specifications for Integrated reception systems (IRS) covering satellite, terrestrial, analogue and digital) and radio (both FM and DAB) to every apartment covered by the system.

12.6 Smoke Alarms

All houses shall be provided with mains powered, self-contained smoke alarms to BS 5446 : Part 1. All such smoke alarms shall have a battery back-up and be linked so that the operation of one alarm will trigger alarms in other locations.

All systems shall be designed and installed in accordance with Approved Document B, Section 1.

Generally one smoke alarm shall be provided per storey, located in a suitable circulation space of the house or apartment and positioned within 7.5m of the door to every habitable room.

Failure of the system should trigger a visual or audible signal.

BS 5839: Part 1 and Part 6 recommend that occupiers should receive the manufacturers’ instructions concerning the operation and maintenance of the alarm system.

12.7 Codes of Practice and BS EN Standards

Min performance of extract fans to BS EN 13141-4 clause 4

Min performance of range hoods to BS EN 13141-3 clause 4

BS 4293: Specification for residual current-operated circuit-breakers

BS EN 60929 Ballast Performance

BS EN 60928 Electrical safety of the fitting

BS EN 61000-4 Electromagnetic Compatibility

BS EN 61000-3-2 Harmonics / 61547 Immunity / 55015 Emission

BS 5446 pts1 & 2: Fire detection and fire alarm devices for dwellings – Specification for smoke alarms

13.1 FINISHES

13.2 General The level of finish to be attained shall be in accordance with NHBC - Technical Standards and additional publication ‘A Consistent Approach to Finishes’.

13.3 Painting – (General)

For gloss or satinwood use 1 primer coat (unless pre-primed) with 1 undercoat and 2 top coats on timber and MDF. For emulsion use 1 mist coat and 2 full coats on walls and ceilings. For wood stains use 2 coats and where appropriate 2 coats of varnish.

13.3.1 Knotting and Stopping

Knotting is to be the best quality Shellac Knotting or other equal approved to BS 1336. Stopper filler to be used in accordance with manufacturer’s recommendations. Filler shall not to be used in excessive thickness.

13.3.2 Primers Primers for various surfaces to be as follows: For treated MDF – “Dulux” MDF Primer Undercoat For untreated softwood, plywood etc – “Dulux” Wood Primer White oil based, except where

‘Weathershield’ Exterior Gloss is used – where the primer should be ‘Weathershield’ Preservative Primer. For treated softwood, plywood etc – “Dulux” Aluminium Wood Primer.

For steel and metalwork and copper pipes – “Dulux” Zinc Phosphate Primer. For galvanised

metalwork – “Dulux” Zinc Phosphate Primer preceded by degreasing and application of

Mordant solution.

13.3.3 Woodwork and Metalwork Gloss and Satinwood paints – to be ICI “Dulux”. The recommended shades of undercoats are to be used to suit the finishing colours required.

Stains – The Stains are to be “Dulux” ‘Weathershield’. To be used together with any appropriate clear base coats.

13.3.4 Walls Finish to plastered walls etc, is to be “Dulux” ‘Super Matt Emulsion’. Where necessary, on extremely porous surfaces of a powdery nature, the application of a “Dulux” ‘Plaster Sealer’ may be required.

Colour, ‘Gardenia’ (BS 10B15) to all rooms.

13.3.5 Ceilings Where specified to plastered ceilings and to plasterboard ceilings with decorative compound, “Dulux” ‘Super Matt Emulsion’ is to be used.

Generally the colour of ceilings shall be’ White’, except for rooms with sloping ceilings. In such cases the sloping part of the ceiling and main ceiling area shall be painted in ‘Gardenia

(BS 10B15)’ colour emulsion as the walls.

Decorative compound surfaces of high porosity may require the application of a sealer prior to the application of the emulsion.

13.3.6 External Render Where render is not self coloured, finish shall be “Dulux” ‘Weathershield’ masonry paint, either, matt emulsion as specified or “Dulux” ‘All Seasons’ masonry paint.

The alternative use of high build may be specified.

13.3 Mouldings

Skirtings and architraves to be MDF, profile and size as described in the Group Buying Manual. Mouldings shall be fixed with a suitable adhesive and pinned to ensure a secure bond.

13.4 Fire Protection

The level of fire protection to be given to an element of structure must be at least equal the part of the building it supports, whether that part is load bearing in its own right or not.

Fire protection to steel beams will generally be provided by “Gyproc Fireline” plasterboard by ‘British Gypsum’ or similar approved proprietary board fixed locally to the beam.

The thickness of the board is determined by the “Section Factor – A/V” (number of exposed sides and the size and mass of the beam) as detailed in ‘British Gypsum White Book’.

Generally, the encasement of steel beams shall be minimum 12.5mm thick “Gyproc Fireline” plasterboard by ‘British Gypsum’ or similar approved, installed in accordance with the manufacturers instructions.