G Structural/Carcassing Metal/Timber

G1 STRUCTURAL/CARCASSING METAL
G10 Structural Steel Framing
G11 Structural Aluminium Framing
G12 Isolated Structural Metal Members
G15 Protective Coatings For Steelwork (For Slam)
G2 STRUCTURAL/CARCASSING TIMBER
G20 Carpentry/Timber Framing/First Fixing
G22 Laminated Timber Loadbearing Panel System
G3 METAL/TIMBER DECKING
G30 Metal Profiled Sheet Decking
G31 Prefabricated Timber Unit Decking
G32 Edge Supported/Reinforced Woodwool Slab Decking

G10 Structural Steel Framing

CONSIDER:
• Design structure for long life: See A90.
• Design frame for deconstruction and salvage in future at end of design life. See A90.
• Reduce the need for cement and aggregates on the project.
• Timber structures made from home grown structural timber or long-span compound timber beams.

RECLAIM AND REUSE:
• Reclaimed steel, from façade retention projects or dismantled buildings.
• Use second hand steel: welded plates, cutting off sections of steel using heat or mechanical means and extra bolt holes will not diminish the performance, especially if it is all covered up.
• At BedZED reclaimed steel complete with redundant bolt holes and weld/cut marks are exposed .

AVOID:
• Arranging small steel columns in thick blockwork walls, causing cutting to web space profile.

G11 Structural Aluminium Framing

CONSIDER:
• Design structure for Long life: See A90.
• Design frame for deconstruction and salvage in future at end of design life. See A90.
• Mill finish aluminium may have a shorter life than coated aluminium.
• Mill finished profiled aluminium roofing reflects the colour of the sky: blue, white, grey or sun.
• Reduce the need for cement and aggregates on the project.
• Timber structures made from home grown structural timber or long-span compound timber beams.

RECYCLING:
• Use recycled aluminium in preference to virgin aluminium, significant reduction in CO₂ generated.
• Design for recycling: avoid coatings as they discourage recycling due to the high levels of purity required in aluminium, PPC and PVF2 are more difficult anodizing is an alloy of aluminium and is more readily recycled, mill finish is best but not everybody likes the oxides that form on aluminium.

AVOID:
• Virgin alumninium - it uses lots of energy and generates CO₂.

G12 Isolated Structural Metal Members

AVOID:
• Arranging small steel columns in thick blockwork walls, causing cutting to web space profile.

G15 Protective Coatings For Steelwork (For SLAM)

CONSIDER:
• Water based paints
• Some paints are supplied in cardboard drums and are compostable.
• Some natural paints are compostable along with the cardboard drum.
• Paints listed in British Museum Schedules for museums
• Absorption of UV light
• Natural traditional paints, stains and oils
• Mineral paints which chemically bond with porous backgrounds, up to 100 years life
• Paints with long life 10 years external or 20 years internal between coatings
• Powder coatings in preference to paint
• Galvanized steel without paint, See Z111

REUSE:
• Store materials to prevent deterioration
• Permit the use of opened and resealed and unopened tins from the contract to be stored on site for use in snagging
• Permit the use of unopened tins from the contract to be stored on site for use in and in 6 month defect repairs
• Permit the use of unopened tins from the contract to be stored on site for use by the FM in maintenance of the building in use

AVOID:
• Most conventional paints which are concoctions of chemicals and volatile organic solvents.
• High VOC paints.
• Synthetic paints.
• Aggressive paints which will affect the exhibits in museums and art galleries.
• Painted steel structure.

G20 Carpentry/Timber Framing/First Fixing

CONSIDER:
• Timber structure in place of concrete to avoid temporary materials (plywood and softwood framing) used in formwork.
• Locally sourced timber: Site first > Town > County > Region > Country > Continent > World.
• Use of any existing trees to be cut down as part of the works.
• FSC certified forest timbe. See Z10.
• Durable timbers do not all come from the Tropical Rain Forests:
- Oak and many other species are durable and are available in the UK and Europe.
• There are durable softwoods as well as hardwoods.
• Off site prefabrication to reduce waste.
• Design structure for Normal 60 years of Long life 120 years: See A90.
• Design frame for deconstruction and salvage in future at end of design life. See A90.
• Softwood or hardwood in place of steel structure.
• Grow trees to be available to replace roof and other timbers in 60-120 years.
• Floor structure, roof frame, decking and ramps are opportunities for timber structures made from home-grown structural timber, reducing the need for cement and aggregates on the project.
• Glued laminated timber where poor strength grade timber can be substituted in the middle of the section where it is least stressed - potential to reduce the self weight of the section without significant loss of strength.
- beware of the adhesives used in laminated timber.
• Use of prefabricated pre-insulated breathing wall, floor and roof panels.
• Consider the use of beams, purlins and rafters in place of trussed rafters to allow use of roof space as accommodation or storage .
• Consider the use of prefabricated pre-insulated breathing wall, floor and roof panels.
• Timber structure in place of concrete to avoid temporary materials (plywood and softwood framing) used in formwork .

REDUCE, RECLAIM AND REUSE:
• Salvaged timber from existing building in:
- Softwood in stud walls, floors or roofs.
- Floor boarding.
- Doors, windows.
• Use compound I section timbers - it reduces the use of timber.
• Use second-hand timber. The FSC recognises reuse of timber.
• Reuse any spares from earlier deiveries on later builidngs on the same site.
• Be consistent in roof spans on a project with many house or other building type floor plans, to ensure that any spare trussed rafters from one building can be used on any other building.
• Use reclaimed timber, structural sections, floors, walls, roofs. At BedZED reclaimed timber studs are used for internal studwork walls and clad in plasterboard.

BEWARE:
• Unseasoned untreated hardwood framed buildings: tree cutting is seasonal, plan projects around this issue.

AVOID:
• Illegally forested timber.
• Non-sustainably managed forested timber.
• Tropical Rainforest timbers, (there are probably other species which will do the job you need from nearer the site).
• Endangered species of timber, (Check the CITIES website).
• Clear felled virgin forest timber.
• Clear felled plantations if not replanted.
• Indonesian Hardwood, most is illegally logged, destroys forests, communities and habitation
• Pan European Forest Certification (PEFC) certified forest timber: it does not address all the issues adequately.
• Formaldehyde adhesives in compound or laminated sections See Z20.
• Synthetic adhesives if natural alternatives can do the job required See Z20.
• Adhesives if fasteners will do the job required See Z20.
• Trussed rafters if roof space can be exploited as accommodation or storage.

G22 Laminated Timber Loadbearing Panel System

CONSIDER:
• These systems are made to measure and so the openings should always co-ordinate with windows and no doors generating zero waste.
• These systems uses more timber than is required to construct timber frame construction walls and give it structural stability, so it can be seen as the opposite of a resource saver.
• These systems do not provide a void to include thermal insulation, although it offers some insulation, it still requires insulation inside or out to bring the U value to the required performance.
• Use of compound I section timbers - it reduces use of timber.
• Use of prefabricated pre-insulated breathing wall, floor and roof panels.

RECLAIM AND REUSE:
Reclaimed stone originally laid in lime mortar stone walling
Suppliers: Salvo at Salvoweb.

AVOID:
• Flush wiring and conduits, requiring cutting and waste.

G30 Metal Profiled Sheet Decking

CONSIDER:
• Permanent steel formwork to concrete floors and roofs, reduce cement and concrete use .

RECYCLE:
• It is unlikely that steel formwork to floors will ever be reusable but recycling will be possible but relatively difficult compared to dismantling concrete frame and insitu floor slabs.
• There may be scope to cut floors to make small floor panels.

AVOID:
• Timber formwork.

G31 Prefabricated Timber Unit Decking

CONSIDER:
• Surface mounting services or hollow linings or hollow skirtings and dados etc. See P20s.

AVOID:
• Arranging small steel wind post columns in thick blockwork walls, causing cutting to web space profile.
• Flush wiring and conduits, requiring cutting and waste.

G32 Edge Supported/Reinforced Woodwool Slab Decking

CONSIDER:
• BS have deleted their work section since no UK companies produce woodwool slab.

AVOID:
• Cement content is a reason to consider alternatives.