WAS031 – Off site Construction – Client Exemplars

Waste Reduction through the use of Steel Frame at SmartLIFE.

Light steel frame construction reduced the waste generated in building houses by 4.8 m³ per 100m2 of construction. A reduction of 22% when compared to traditional construction.

Project code: WAS031 ISBN: 1-84405-392-X Research date: January 2008 Date: May 2008

Front cover photograph: Steel frame panel erection on the BRE SmartLIFE project

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Published by Waste & Resources The Old Academy Tel: 01295 819 900 Helpline freephone Action Programme 21 Horse Fair Fax: 01295 819 911 0808 100 2040 Banbury, Oxon E-mail: info@wrap.org.uk OX16 0AH

Executive summary It has often been said that the use of off site or Modern Methods of Construction (MMC) results in the production of less waste, but the evidence to support such a statement it usually lacking. To address this WRAP has commissioned a series of case studies (WAS 031 Off site Construction – Client Exemplars) which looks at different systems. In each case the series seeks to address this issue by looking at the waste generated by the off site system on the building site and in the factory where it was produced and comparing this with the waste generated by traditional construction. This study has looked at light gauge steel frame houses built by Inspace using kits supplied by Fusion Building Systems as part of the SmartLIFE project in Cambridgeshire. The steel frame kit consisted of cold rolled steel frame walls which are encapsulated in polystyrene thermal insulation at the factory. These are supplied with steel frame floor cassettes. The houses built using the steel frame kits were monitored and compared with houses of a similar design produced in traditional masonry construction. In both cases the amount of waste generated by volume has been measured on site for the whole of each building and in the case of the steel frame house kits at the Fusion factory as well. The waste from the factory is then added to the waste produced on site. These volumes are then used to create:

Environmental Performance Indicators (EPIs) by dividing the volume by floor area constructed to give waste in m3 per 100m2 of floor space (roughly the area of a small house), and,

Key Performance Indicators (KPIs) by dividing the volume by the project value to give waste in m3 per £100K project value

Building in steel frame reduces packaging, insulation and concrete product waste – a full breakdown is shown in section 3.0 of this report. By using steel frame kits the waste generated by the construction of the houses was reduced by 4.79 m3 per 100m2 of floor space (22%) or 4.16 m3 per £100K project value (22%).

100m2 is the floor area of a small house. Therefore for a project of 500 houses we would expect their to be a reduction in the waste produced of around 2400m3..

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Contents 1.0 The Construction Project.......................................................................................................... 3

1.1 Project description.................................................................................................................3 1.2 Reasons for using steel frame ................................................................................................3

2.0 The Factory and Construction Process..................................................................................... 4 3.0 Waste Comparisons with Traditional Build .............................................................................. 7

3.1 Data .....................................................................................................................................7 3.2 Reasons for the different results...........................................................................................10 3.3 Scope for reducing waste further using the steel frame system: .............................................11

4.0 Where Steel Frame is Used .................................................................................................... 11 4.1 Extent of usage ...................................................................................................................11 4.2 Types of projects in which steel frame is used.......................................................................11 4.3 Strengths and weaknesses of steel frame..............................................................................11

4.3.1 Quality ...................................................................................................................11 4.3.2 Speed ....................................................................................................................11 4.3.3 Sustainability ..........................................................................................................12

5.0 Fusion and their Facilities ...................................................................................................... 12 5.1 Background.........................................................................................................................12 5.2 Current waste management practices ...................................................................................12

6.0 Conclusion.............................................................................................................................. 12

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1.0 The Construction Project 1.1 Project description Client Home Group and SmartLIFE Project Manager BRE Developer Home (Housing Association) Steel Frame Manufacturer Fusion Building Systems Main Contractor Inspace Regeneration Partnerships and New Homes Ltd Architects Churchill Hui Architects Investor/funder English Partnerships, Housing Corporation, Fenland District Council,

Cambridge County Council and Department for Communities and Local Government

Timescale Start September 2006 Practical completion September 2007

Contract value £5,569,236.00 Output 56 homes (35 light gauge steel frame / 21 traditional) Site area 1.1 hectares Density 50 dwellings/hectare The houses were built in March, Cambridgeshire as part of the SmartLIFE project in which houses of similar design were built in a variety of different systems including traditional so that the efficiency of the construction processes could be compared. SmartLIFE is a project set up for the Cambridge area where increasing demand for housing is likely to lead to a skills shortage. Building MMC housing allows for this demand to be met with a reduced labour requirement. As well as monitoring the construction of houses using forms of MMC such as steel frame, the SmartLIFE project has also built an MMC training centre. 1.2 Reasons for using steel frame

Steel frame was one of the types of MMC monitored as part of the SmartLIFE project. The others were timber frame and in-situ concrete formwork. Examples of projects where the Fusion System has been used includes:

• Merton Lodge: A four storey Premier Travel Inn – Developer; Wates – Client; Whitbread • Brooks Road: 30 town houses – Developer; ROK • St Hughes Ave: 12 houses – Developer; Inspace – Client; Beacon Hosing Association

Steel frame is used because it is light but strong with a high degree of accuracy. It does not shrink like timber frame, but will still expand and contract. The off site construction techniques of the Fusion Building System provide a structure to the house rapidly. The panels in the external leaf of the building are supplied to site encapsulated in fire retarded EPS (expanded polystyrene) insulation, eliminating the need to install insulation on site.

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2.0 The Factory and Construction Process This flow-chart shows the process from manufacture of the steel frame in the factory (blue) through to erection on site (green).

Sheet metal is delivered to the factory in large rolls.

Light Gauge Steel is roll-formed for the tracking.

Joists are formed, cut to length and punched through to make way for services.

Steel members are fitted together on the assembly line.

OSB is cut to length and fixed with adhesive onto steel floor cassettes.

The steel is encapsulated in EPS for insulation at the factory.

Cut-offs of the EPS re-used where possible.

EPS is sent to be recycled into plastic products.

Panels are stored in the factory and delivered to the construction site.

Units are constructed on site with services and plasterboard fitted and fixed.

The external cladding is finished with brickwork and render.

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The first manufacturing process for the light gauge steel frame is to roll form the tracking of the steel members for the wall and floor systems. Very little waste occurs, but when it does it is due to faults in the tracking being either too wide, too narrow or inconsistent deeming them unusable. Waste from the process of roll forming has been further reduced recently by Fusion using a machine that joins together the end of one steel coil with the start of another and through ordering larger coils of sheet steel. Steel scrap:

Steel joists are produced in a similar way and any off-cuts of the joists are stored and used as stiffeners. Floor joists are punched through to enable services to passed through the floor structure. The steel that is punched out is collected and used as “stiffeners” elsewhere on the frames. Punched steel: Collected waste to be used as “stiffeners”:

The next process after all the elements of the steel frame have been cut to size and manipulated into shape is for them to be fixed together on the assembly line. Floor cassettes use a steel frame but require OSB to be cut and fixed with adhesive. Any off-cuts of OSB are placed in the timber skip along with any other timber waste products and pallets. Currently packaging waste from assembly and general waste is put into a non-segregated skip that will go to landfill. Fusion are looking to options to recycle this waste stream. Packaging waste:

EPS for the insulated steel frame is made at the factory by heating and expanding the material through steam and pressure. Off-cuts of the EPS insulation are reused wherever possible to reduce thermal bridging in wall systems in between members and around openings. Any other waste is compacted along with polystyrene packaging waste. The polystyrene is compacted into the shape of railway sleepers for transportation to recyclers where it is sent on to be used to produce such things as coat hangers, other plastic products, etc.

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Collected EPS Compacted polystyrene

Completed panels are stored in the factory and delivered to the construction site. Timber bearers between the packs, are off-cuts from the manufacturing process. These were observed to be thrown away when they arrived on site. After the panels have been erected internal services and plasterboard are fixed. Roof cassettes are lifted in place providing the floor construction for the first floor and services are run through the steel floor joists. External finishes are provided by rendering and brickwork as the steel frame forms the inner leaf of the cavity wall. The roof structure is a conventional system using timber trusses. Wall panel erection Floor Cassettes being craned in

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3.0 Waste Comparisons with Traditional Build 3.1 Data Data was collected on steel frame (on site and in the factory) and traditionally built dwellings of similar design using the the BRE’s Smartwaste system that classifies waste into 14 categories (see table below). Smartwaste can be used to produce Environmental Performance Indicators (the waste by volume with regard to the floor area and Key Performance Indicators (the waste by volume with regard to project value).

EPI KPI Waste generated with regard to floor area constructed (m3 per 100m2 of floor space)

Waste generated with regard to project value (m3 per £100K project value)

Traditional Steel frame Traditional Steel frame

Reasons for results Green figures indicate an improvement in waste efficiency Red figures indicate a drop in waste efficiency

Ceramics/bricks 4.05 3.93 3.52 3.42

Inert 0.13 0.13 0.11 0.11

Electrical Equipment 0.22 0.21 0.19 0.18

Liquids and Oils 0 0 0 0

Plastics 0.13 0.13 0.11 0.11

Packaging 3.80 2.69 3.30 2.34 Less blockwork therefore less pallets

Canteen/office/ad-hoc 0 0 0 0

Metals 0.04 0.06 0.03 0.05 Off cuts from steel frame production

Insulation 1.78 0.85 1.55 0.74 Insulation fitted in factory(more controlled)

Concrete 5.03 1.60 4.37 1.39 Steel replaces the blockwork inner leaf

Hazardous 0 0 0 0

Timber 3.31 3.43 2.88 2.98

Plaster/cement 3.14 3.81 2.73 3.31 More plasterboard used

Furniture 0 0 0 0

The reasons for waste differences are discussed further in section 3.2.

Total 21.63 16.84 18.79 14.63

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3.2 Reasons for the different results Cement products: more waste when used in traditional building. The steel frame replaces the internal block work leaf in traditional construction. This naturally results in a large reduction of the amount of block work and mortar waste (which are both classified as cement products). Steel frame inner leaf Blockwork inner leaf

Insulation: more waste when installed in traditional buildings. The steel frame external walls are encapsulated in insulation at the factory which is much less wasteful than installing insulation on site in a traditional cavity wall. In traditional construction the insulation is fitted by the brick layer on site. This is much more difficult to control than the steel frame case and therefore generates much more waste Steel frame factory fitted insulation Insulation panel in cavity

Packaging: more waste when building traditionally. There is much more packaging required for blocks (pallets, and plastics), than for steel frame panels. Most of this additional packaging ends up in the skips. Plasterboard: more waste when used on steel frame. There is more plasterboard used in the steel frame units than traditional units. This is explained by the fact that external walls are drylined inside the steel frame, where as in the traditional houses the blockwork walls were plaster skimmed. The drylining process produces a lot of plasterboard off-cuts, but this increase in waste is more than compensated for by the waste savings for the other materials.

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Plaster board fixed on steel frame Plaster skimmed on traditional

3.3 Scope for reducing waste further using the steel frame system: Fusion have further plans to improve their environmental performance and to reduce their raw material and waste disposal costs by:

reusing waste EPS in house;

developing product from steel waste;

purchasing a timber shredder and a regrinding machine for the EPS to increase waste density in the skips;

buying a combined heat and power boiler to burn the waste timber; and

reducing packaging waste.

4.0 Where Steel Frame is Used 4.1 Extent of usage Light steel frame manufactured as frame or panel within a factory environment is produced by four major companies. The turnover of the entire sector for all types of panel is estimated at £61 million which is 4% of the off site construction industry (Off site Industry Survey 2006, Buildoff site). 4.2 Types of projects in which steel frame is used Light steel frame construction is mainly used within the residential sector for houses and flats. The maximum heights of these buildings vary from manufacturer to manufacturer, but are typically between four and six stories before hot rolled reinforcement has to be incorporated. As a build method it is adopted by builders as an alternative to masonry construction because it allows the creation of a weather tight shell more quickly. This is particularly important in flats where the whole block will need to be weather tight before the any of the flats can be completed. 4.3 Strengths and weaknesses of steel frame 4.3.1 Quality It is likely that steel frame units will have a greater conformance to the original design than masonry dwellings, because the factory fabricated components can be produced more accurately. This will be important when considering thermal and acoustic insulation and airtightness performance, as these are particularly difficult to rectify once the house has been completed. 4.3.2 Speed Typically steel frame houses, depending on their design and size can be weather tight within five days. This would normally take several weeks in conventional building. On the SmartLIFE project, 50% less man hours was spent on super structure for steel frame compared to traditional.

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4.3.3 Sustainability Steel frame buildings has some strong environmental credentials. Waste has already been discussed in this report, but there are other areas:

steel has a large recycled content, but a high embodied energy: and

the depth of the frame can be easily adjusted to accommodate a variety of insulation thicknesses.

The low thermal mass of steel frame structures can leave steel frame buildings vulnerable to overheating. However low thermal mass can be advantageous where the occupants want rooms to cool down quickly (eg bedrooms). Overheating can be compensated for by well designed shading and ventilation. 5.0 Fusion and their Facilities 5.1 Background Fusion is a large privately owned steel frame producer based in Cork in Ireland. They produce steel frame walls, floor cassettes. The walls are uniquely encased in EPS insulation in the factory to avoid installation on site. 5.2 Current waste management practices Fusion has segregated skips for general waste, treated timber, untreated timber, light gauge steel and hot rolled steel waste. Treated timber has to be segregated as it is contaminated and is generally sent to land fill. Offcut steel is reused as stiffeners for the joists. Tracking stud off-cuts become noggins. Improved machinery has just been installed to limit waste on tracking. The machine joins coils together and the steel coils are delivered on larger reels. Holes are punched out for services. These punchings are collected and used as plates for joists. Fusion are considering having a shredder for metal on site to increase the steel density within the skips and therefore reduce the number of skips required. EPS offcuts are used wherever possible to prevent cold bridging, in between members, around doors and around windows the off-cuts are used up in the factory. Other larger off-cuts are saved and taken to site where they are used in between panels, internal partitions or other parts of the build. Any EPS that is too small or is a difficult shape is collected for recycling along with the white polystyrene used for packaging material coming into the factory. For Sundry Packaged Materials (mastic, insulating foams), Fusion are implementing a policy of collecting the small quantities of packaging involved for re-use/recycling by the original manufacturer. Where possible, Fusion are investigating the use of products with low inherent wastage and packaging. Oriented Strand Board (OSB) is used by Fusion for floor decking. OSB by its nature is a material which uses the small off-cut/waste materials generated by primary timber production processes. The timber in the OSB used by Fusion is sourced from sustainable timber resources. Fusion factory fit the majority of their OSB to factory produced floor cassettes, which are designed at a size to minimise off-cut wastage. The majority of off-cut material is also used in cassette production, which is made possible by the virtue of a factory environment. All OSB waste is recycled An environmental policy has been produced that details the origin of materials and the manufacturing activities of Fusion. 6.0 Conclusion Steel frame is a growing form of MMC. It’s use allows for reduced time on site. This case study has measured the amount of waste produced in constructing a complete timber frame houses from start to finish at the SmartLIFE project in March, Cambridgeshire and added this to the amount of waste produced in the factory that made the timber frame kits (Fusion Building Systems). This was compared to the amount of waste produced by producing houses of a similar design in masonry. It could be argued that this

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unfairly penalised the off site method, but even under these circumstance the waste generated was reduced by 4.79m3 per 100m2 of floor space constructed (22%) or 4.16m3 per £100K project value (22%) . Making steel frame units in a factory aids in the minimisation of waste and the segregation of waste when it is produced. By adopting steel frame less raw material is handled, cut and fitted on site and this also reduces the waste produced. The Fusion System is unusual in that it comes factory-insulated and this contributed significantly to the reduction in the waste (0.93m3 per 100m2 or 0.81m3 per £100K project value). Having said that it is still clear that even those steel frame systems not insulated in the factory, would if adopted instead of masonry in housing projects lead to a reduction in the amount of waste produced.

Written by: Emmanuel Moulinier, Russell Banton, Christopher Gaze

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Published by Waste & Resources The Old Academy Tel: 01295 819 900 Helpline freephone Action Programme 21 Horse Fair Fax: 01295 819 911 0808 100 2040 Banbury, Oxon E-mail: info@wrap.org.uk OX16 0AH www.wrap.org.uk