Although housing with wood frames is very common in many parts of the world (America, for example), it’s not often found in Britain these days. Yet it’s a very durable form (the oldest standing timber building in the U.K. dates from the 12th century). It’s a good, sustainable resource (at least European softwood is), but all too often wasted. It’s estimated that 2.5 million tonnes of wood each year is wasted in the U.K. from construction alone, and 3,000 tonnes of re-usable timber is burnt or put in landfills every single day.
Forests act as carbon sinks. Especially when young, they take more CO2 from the atmosphere than they give back. When you use timber in a house, you’re not only storing that carbon in the wood frame (typically 28.5 tonnes of it in a wood-fame house of 216 sq. m), you’re also giving the forests a chance to regenerate.
Unfortunately, the relatively low cost of lumber doesn’t provide a great incentive to eliminate waste. However, sustainable development is changing that. The idea of “advanced framing” is catching on, where unnecessary framing elements are left out, no structural members are oversized, and window and door elements are properly aligned with the frame.
The recovery of waste wood in the construction process is improving, although it has a long way to go. Only about 35% of “demolition wood is usable, although the process of “deconstruction” (carefully disassembling older building stock) is becoming more commonplace.
You can buy pre-packaged wood frame homes, or you can construct on your site. In this country the wood frames are often brick-covered, although that’s not necessary – many different materials will do the job. But the more wood you use instead of something else returns a lot to the environment – 0.8 tonnes of carbon dioxide for each cubic metre, in fact.
You’ll need to put in a “breather membrane” on the external faces. Not only does it protect the wood during construction, it stops rain penetration that can cause damage. Additionally, you’ll need a layer of vapour control between the plasterboard and the insulation. Polythene sheets works very well for this, or look for plasterboard with a built-in vapour control layer.
There are many different sustainable insulation types of thermal insulation you can use with wood framing. Isonet, for example, is a very effective mix of hemp fibres and recycled cotton, with a favourable u-value. Natural wool or rockwool (which comes from steel slag heated together with volcanic rock at high temperatures) are other alternatives, and both are available in batts and blankets. There’s also cellulose insulation, which comes from recycled newspapers. However, you need to watch out for the printer’s ink – it can leak formaldehyde. Agricultural fibre insulation can be good; you buy it in batts that have been treated with a fire retardant (a non-toxic one) Cementitious foam insulation is quite natural, too, and blown into the walls (it’s made from magnesium that’s been drawn out of sea water).