November was a good month for air leakage testing. Two houses we designed are currently on site, in Barham and Herne Bay. Both use timber frame but very different types- one is an I joist NIPPS system, the other a double stud system. In both cases our clients are heavily involved in the build process and making sure that our airtight details are followed. This has produced excellent results of below 0.4ach in each case.

We have also witnessed an air test on a house we designed in 2006/7 which has taken 15 years to self build. This achieved 1.78ach, despite our last advice on air leakage to the self builder being around 10 years ago!

We are also in the season of testing existing buildings as preparation for retrofit. A common finding on older solid walled properties is that the old parts of the house are quite air tight, but any new extensions are the weakness, owing to poor modern construction techniques. We find rigid foam insulation thrown into gaps with poor fit, and multi-foil type insulations that just don’t work. Any retrofit has to start by correcting these defects before we can move on to other improvements.