Mocking up the roof insulation at the eaves

With the roof structure up, the builder and the wall insulation team have been working out the eaves detail.

For ultra-low energy buildings, it is extremely important that the roof insulation meets the wall insulation without any gaps. And if you need to achieve air tightness as well, more interesting still.

The best way to figure it out is to mock up the various options. First 100mm of insulation above the rafters, with a pretend bit of weatherproof membrane to fix to the outer face of the brickwork (for air-tightness).

Then wall insulation, and a second layer of weatherproof membrane (stuck firmly to the first where they meet). This second one diverts water into the gutter, so must end up above the counterbattens.

Glad we've got that sorted.