Design : Build: Roof Insulation & Waterproofing

January 22, 2011

Roof Insulation & Waterproofing - Day 2

Today we continued installing the insulation on the roof and pressed ahead with the waterproofing.

As previously mentioned, the insulation is covered by a waterproof membrane that is breathable. This breathable membrane is required by the UK building regulations, but it's actually really great. Once it's on, the roof essentially become waterproof and can stay that way for several months before the slates get put on. The membrane is held by wooden battens which will ultimately be used to nail the slates in place.

The goal today was to install some more insulation, but to also put down the first few rolls of breathable membrane. This would also require us to fasten the first few battens using a special helical nail that is 200mm long (8 inches). This special nail should save us a considerable amount of time as it fastens the entire roof assembly (battens, waterproof membrane, 120mm insulation, and the damp-proof course) directly to the rafters with one nail. I had originally bought many wood studs to hold the insulation down, which would have taken considerable time to cut and install. Now we can use this wood to do other things.

The trick with these helical nails is they have to go into the rafters below. This is much harder than it sounds because we have 7 inches of insulation, planks and plastic hiding the exact location of the rafters. The way around this is to mark the rafters locations with pencil onto the top layer every so often, before covering everything up.

I was nervous to see if all of this would work and save time...