G20 Carpentry Timber Framing First Fixing checklist

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G20 Carpentry/Timber Framing/First Fixing Checklist

G20 Carpentry/Timber Framing/First Fixing Checklist
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Index:

Problems:

Tree cutting is seasonal:
- unseasoned hardwood framed buildings:
- be aware of the potential for delay until next tree cutting occurs,
- plan projects around this issue
Acidic species:
- tanning run off can stain porous materials below,
- provide temporary or sacrificial protective materials or coatings
- can corrode or stain ferrous metal fasteners or visa versa
- use austenitic stainless steel fasteners (screws/nails etc.)

Misunderstandings:

Durable timbers do not all come from the Tropical Rain Forests
There are durable softwoods as well as hardwoods
Prefabrication off site does not reduce offcuts,
- but the off cuts have a greater potential to be used in a factory rather than put in a skip on site

Solutions:

Grow trees to be available to replace roof and other timbers in 60-120 years
Use any existing trees that are to be cut down as part of the works

Consider:

Choose locally sourced timber:
- first > last:
- Site > Town > County > Region > Country > Continent > World
FSC certified forest timber,
- it addresses more of the sustainability issues,
- 276 sources in the UK.
Oak and many other species are durable and are available in the UK and Europe
Off site prefabrication to reduce on site waste
Design structure for appropriate life See A90
- Short life: 30 years
- Normal Life: 60 years
- Long life: 120 years:
Design frame for deconstruction, salvage and reuse in future at end of design life. See A90
Softwood or Hardwood in place of steel structure
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
Use of prefabricated pre-insulated breathing wall, floor and roof panels
Timber structure in place of concrete
- to avoid temporary formwork materials (plywood and softwood) used in formwork,
- potentially used a few times then thrown away to landfill as waste

Avoid:

Wood substitutes: unless it is 100% recycled plastic
- Cradle to Cradle:
  - avoid blending natural (wood fibre, wood flour) and technical (plastic binder)
  - ingredients that cannot be separated at end of life,
- Proviso: unless the manufacturer:
  - leases the product to the user,
  - has a tack back scheme in place,
  - is already recycling their own post consumer product
Illegally forested timber
- (Use EUTR procedures)
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)
- See GBE SPECIES TABLE
Clear felled virgin forest timber
Clear felled plantations if not replanted
Indonesian Hardwood,
- most is reported to be illegally logged:
- destroys forests, communities and habitation
Adhesives if fasteners will do the job required
Burning timber off cuts on site

Minimise:

PEFC certified forest timber, it does not address all the sustainability issues adequately, choose FSC first
Synthetic adhesives if natural alternatives can do the job required

Substitute:

Specify by performance requirement then the suppliers can choose available FSC species to do the job required and offer a range of colours close to your requirements

Health:

Avoid formaldehyde adhesives in boards, compound or laminated sections See Z20

Wellbeing:

Use planed and arrised softwood sections to minimize splinters whilst handling sections

Safety:

Normal manual handling and mechanical handling safety measures
Bulk timber is heavy and has momentum at the end of a sling from a crane

Precautionary principle:

Use a sacrificial coatings during handling and installation
Sand off all sacrificial coatings prior to hand over leaving in pristine condition

Resource Efficiency Issues:

Reduce:

Use compound I section timbers, in place of solid sections:
reduces use of timber, resource use reduction
reduces fuel to transport
easier to handle on site, often by just one person

Reclaim:

All healthy timber that can be reused

Reuse:

Second hand timber
FSC now recognises reuse of timber
Salvaged timber from existing building in:
- Softwood in stud walls, floors or roofs
- Floor boarding
- Doors, Windows

Recycle:

Damaged untreated timber
Make bat and bird boxes with offcuts
Use as mulch in landscape

Recover:

Nutrients from untreated timber by composting
Energy from timber offcuts by saving in a biomass fuel store for use in the employer’s biomass boiler

Waste Issues:

Hazardous waste & Deleterious Substances:

Preservative treated timber is hazardous
Do not use preservative treated timber in bat and bird boxes
Do not use preservative treated timber in childrens toys
Do not use preservative treated timber in food growing planters, raised beds
Preservative treated timber is potentially inert in landfill, but leaching may occur

Waste statistics

30 m tonnes (33% of 90 m. tonnes/year) of waste is offcuts (not all timber)
9.4 m tonnes (10.2% of 90 m. tonnes/year) of waste is Temporary works, Site hoardings and Formwork

Waste minimisation:

End of Life options:

Dismantle for reuse (build it with the right fasteners)
Choose durable species

Appropriateness:

off site prefabrication to reduce waste:
Use of prefabricated pre-insulated breathing wall, floor and roof panels

Competence:

Reclaimed timber for reuse:
- check suitability for use in structural application
- there are 900 timber strength graders in UK
- some structural engineers will assess timbers for reuse
Choose species with the right properties for the job
- Don’t choose your favorite coloured species for every application
- Don’t choose your favorite coloured species for external applications the colour will fade to silver or grey

Effectiveness:

Steel sections can be smaller than timber to meet structural requirements
If fire resistance is required steel sections get considerably bigger than timber
Encasing steel or applying intumescent paint increases cost and environmental impact
Timber sequesters carbon from the atmosphere so reduced atmospheric carbon now
Timber buildings can be carbon negative