Why Timber Frame…?

In Europe the building sector is responsible for half of all energy use and therefore half of all carbon consumption. According to Corrim (Consortium for Research on Renewable Industrial Materials) timber frame houses are better for the enviornment because wood uses less energy and that, results in fewer greenhouse gases than alternative materials. In a life-cycle assessment it found that timber-framing consumes less total energy during its ‘lifetime’.The embodied energy of a building is the energy of a building that has been required to extract, process and manufacture it then to transport it to the building site. The highest embodied energy is found in metals. The middle range of materials such as bricks and blocks also require a lot of energy in their manufacture. The lowest embodied energy is in materials, such as building timber, that require only simple processing. Salvaged materials and local materials (straw bales rush matting and mud bricks) require virtually no energy.
What is the difference between timber frame walling and partial fill cavity walling?
The standard timber frame system consists of a waterproof membrane, sheathing board, structural timber frame, vapour barrier and inner lining of plasterboard. The insulation is placed between the timber frame uprights, and the thickness matches the size of the frame.Cavity walling consists of two masonry leafs side by side, a set distance apart but carefully tied together. The bottom of the cavity can drain and the inner leaf should remain entirely dry.However, Joseph Little, Project Architect with Bolton Construction writes in ‘Construction Ireland’ (Vol. 8, Issue 2) that we are reaching the limits of partial fill cavity walling. Wider and wider insulation batts are pushing the masonry leafs further apart and making wall ties longer, which has implications for the structure.Partial fill cavity walling is not a ‘traditional’ building method. On the contary, cavity walls have only being promoted in the Post-War era as a technollogical answer to problems posed with the externally rendered (un-insulated) 215mm solid block walls of the Inter-War years. Partial fill cavity walling belongs to a different era, an era when heating fuel was less expensive and the negative inpact of high CO2 emissions was unknown.Little goes on to write that since 1998, 250,000 new homes have been built to the older and less efficent building standards with inherently high CO2 emissions. Studies show that 8 out of 15 houses with partial fill cavity walling are under-performing and since there are too many variables influencing the effectiveness of partial fill cavity blocks, wet walls become a serious problem.8 out of 9 timber frame houses exceed the design requirement, because with timber frame systems, builders are able to compress quilt insulation, raising the insulation levels beyond what is legally required.Unstable rising oil and gas prices mean that energy efficent homes will be much sought after. It is not an exaggeration to suggest that houses built with interior methodologies and/or materials may, in the future, become worthless.
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