Saturday’s Eco Open House was a success with 43 visitors from all walks of life. Running through the logic of what I’d done half a dozen times helped me clarify my thoughts. Retrofit is complicated and very site/situation specific. The take up of cement and oil based finishes in the 20th century means the vast majority of solid walled buildings are sealed up meaning the fabric is likely to be degrading either quickly or at least slowly. We need to return to a breathable fabric and so ‘traditional’ methods, i.e. lime, perhaps with a bit of technology thrown in. External wall insulation (EWI) is no different and a blanket approach pushed by the big players using oil based insulation is not applicable in many cases. I accept oil based EWI has it’s place for ‘modern’ construction where DPCs, cavities, overhangs etc etc can keep the fabric dry but cannot see how a relatively unbreathable oil based insulation on solid walls will not simply act in a similar manner to cement based render, trapping moisture. Is the likely take up of EWI to meet our carbon obligations not an opportunity to put right the errors of the 20th century and return our buildings to health?
Lime plaster – brickwork – woodfibre insulation – lime render : breathable