Window trim might sound merely cosmetic, however it is very important to creating a watertight shell, and with this kind of construction it is even more complex and important than normal, and finishing the windows and the wall insulation are jobs that go together. We might have installed the windows a while back but, really, that was only the first stage. With over 11″ of insulation butting up against the windows and extending out beyond them, there was substantial work to be done in coming up with and implementing the most waterproof and airtight trim. The best and most cost-effective solution turned out to be renting an aluminium bending machine and using it to make our own custom fit trim from rolls of aluminium, which is fitted over a wooden outer frame. We went for a neutral colour that matched the sills we’d already had made.
Despite what the windows may have looked like earlier in the process – and we installed them as far out as they safely could be – they will end up being set quite deep into the fully insulated walls. There were two potential disadvantages to this: the first is that it would reduce the solar gain, but Malcolm at Construction Maison Passive has done the calculations and we’re okay; and, secondly we would see less of the lovely red frames than we might otherwise have done. The latter turned out to unavoidable where we have non-opening windows (i.e. four out of the five big ones on the south side), but otherwise the colour will still be strong. However, this will be a very effective solution, and because we were able to bend the aluminium any way we wanted, Chris, out builder, has been able to eliminate the need for any extra siding trim (which tends to be much more expensive than siding itself) around the windows: the aluminium will serve multiple purposes.
The crew is now pressing ahead with both window trim and wall insulation, with the most difficult south side being done first. Here, not only do the insulation blocks have to fit around the largest windows and the biggest door, but they also have to fit around the supports for the porch roof.