The roof is stripped of tiles, but we are leaving the felt and battens to provide weather protection until ready with the new membrane, insulation and roof covering.
We need to extend the width of the roof at the sides (verges) and also at the gutterline (eaves) to “receive” the additional thickness of the EWI (external wall insulation). My builder has built additional verge ladders and extended the existing rafters at the eaves. The eaves is a tricky detail for a number of reasons: we need to wrap the airtight membrane around the ends of the rafters and tape it back to the walls; we also need to be careful that we are not extending the rafters to far so they will get in the way of the first floor windows.
The builder has made a mock-up of the eaves detail and also constructed a plywood box in the window reveal – the ply box will make it easier to get a really good airtight installation for the window AND crucially help us to locate the window within the EWI insulation zone which will achieve a much better thermal performance than if the window was installed within the brick reveal.