Section 04ROOF

1. Trusses are to be installed according to the manufacturer’s details, inclusive of temporary bracing for Spandrel panels (if specifi ed within the design).

2. Spandrel panels are to be used in all party walls, with the exception of plots where there are steps and staggers. This is a mandatory requirement.

3. Gable restraint straps must be fi xed as per NHBC Standards clause 7.2.8. Currently utilising a minimum of 4 fi xings to solid noggins over a minimum of 3no. rafters, with at least one fi xing in the third rafter. (Note: NHBC are reviewing this clause for 2017 editions of the Standards onwards).

4. Ensure correct BBA approved vapour permeable (LR type) membrane is usedto BS EN 13859-1 and BS 5534.

5. Depending on insulation depth and pitch of roof either Manthorpe G500 or G502 to be installed at Eaves.

6. All tiles which are required to be cut MUST be wet cut individually on a sacrifi cial board on the scaffold or on the ground, not on the roof itself.

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7. Lead fl ashings to be applied to all GRP upstands. The fl ashing onto a monocouche wall must be installed prior to being rendered.

8. Mastic to all fl ashings to be neat and not overhanging lead work.Flashing to link with cavity tray and weep holes.

9. Paternation oil must be applied to lead immediately after installation.10. Party walls to have continuous insulation quilt from ridge to external eaves

above and below felt cover.11. Framing to be installed behind fascia to take gutter brackets.12. All roof vents to have securely fi xed fl exible connections.13. Roof tiles and fascia to be left clean of mortar marks. Ridge hip tiles must be

fi xed in line and pointed neatly.14. Wall Plate restraint straps are to be securely fi xed to blockwork using plugs

and screws, minimum of 4no. fi xings.15. When erecting roof trusses ensure the use of a truss ladder for joinery

access to fi x high level bracing.

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Typical timber valley construction, providing full support located between trusses for roofer to install GRP valley.

High level bracing and restraint straps to be fixed horizontally.

Restraint straps fully supported. Straps to be located centrally on supports.

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Bracing to be fitted tight to blockwork.

Restraint straps to be fully supported and bracing tight to wall.

Accurate neat cuts to diagonal bracing and fixed to wall plate.

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Fully nail hangers for ceiling joists and ensure tightly fitted together.

Where straight restraining straps are used install a noggin fixed horizontally with a minimum of four fixings with at least 1 in the third rafter.

Timber or steel dragon tie bracing to be used to prevent spread of hip rafter.

Neat tightly cut jack rafter detail.

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Insulate any gaps between trusses and gable/party walls.

Support diminishing trusses with accurately cut timbers at each main truss.

Plate restraint straps are to be securely fixed to blockwork using plugs and screws, minimum of 4no. fixings.

Provide edge protection for roofers. Max. height 950mm for the guardrail and a gap of no more than 470mm.

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450 x 30 x 2.5mm fixing straps are required to secure the spandrel. Minimum fixings are 4no 3.35x65nails into timber framework and 4no 50mm long 4mm dia screws plugged into blockwork.

When using gable spandrels with flush eaves first truss to be positioned tight to spandrel and fixed with a minimum of 3no 75mm angular ring shank nails at 600mm centres as per manufacturer’s instructions.

Gable wall insulation to be continuous to 300mm above wall plate for cold roofs, with breather membrane lapped over. Gable Spandrels are not standard specification.

Party wall spandrel panels should be pre boarded single leaf, as per Robust Details Appendix A1. See Standard Detail DB-SD05-010. All panel joints must be sealed and covered to maintain fire and acoustic integrity.

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Leadwork formed prior to installation of dormer and fully supported to prevent sagging.

Install temporary rain water down pipes with the gutters.

Ensure adequate support is in place for the membrane and insulation is taken from the top of the cavity barrier and installed to the top of the wall plate. Gutter brackets to be installed to manufacturer’s recommendations, generally 600mm centres.

Where possible locate downpipes over expansion joints.

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2010 & 2013 Building Regs. require Thermal Economics Platinum Board Insulation to the outside. Wall plate should only be insulated with TE 2L2 for 2006 Building Regs.

Ensure 100x25mm timber back plate is fixed to roof trusses prior to fascia providing extra support for gutter brackets.

Vented soffit with double row of ventilation required for attic trussed room in the roof housetypes.

Depending on insulation depth and roof pitch either Manthorpe G500 (325mm) or G502 (650mm) to be installed at Eaves.

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Call offs must be realistic. Regular communication with suppliers will help ensure punctual delivery.

Roofspace panel joints run ridge to wall plate.

Package includes gable and party wall spandrels (See Robust Details Appendix A2).

Table scaffold lift to be installed prior to roof arriving.

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Panellised roof systems to be used for room in the roof types. Refer to working drawings.

Consider panellised roofs for bespoke room in the roof housetypes.

Dormers and rooflights are included with panellised roofs as standard.

Preferred John Brash JB-Red battens to comply with BS 5534 (2014). NHBC Standards 7.2.17 require no more than 1 joint in 4 battens on one truss where batten spacing is more than 200mm. For spacing less than 200mm no more than 3 joints in 12.

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Ensure correct roof membrane is installed. All Underlay shall be approved BBA accredited vapour permeable (LR) type to BS EN 13859-1 and compliant with BS 5534 underlay wind uplift resistance requirements for the house type, site location and batten gauge to be used.Underlay to be laid having minimum horizontal lap of 150mm and vertical laps of 100mm in accordance with BS 5534.

Vent tiles should be provided by the roof tile manufacturers to ensure they are fit for purpose.

Cut plain tiles are not acceptable. Purpose made plain tile-and-a-half or half tile must be used. Additionally, cut single lapped interlocking tiles must not be used.

All pitched roofs with rafter pitches from 45 to 54 degrees all tiles are to be nailed twice where two holes are provided by the manufacturer and comply with the requirements of BS 5534.

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Leadwork typically finished to both variations of dry verge

When installing dormers ensure Standard Detail DB-SD05-008 is followed. Ensuring a 15mm gap is maintained between tile and GRP dormer.

Ensure soakers are installed and fully lapped by flashing.