paper igloo architecture and design

Insulating the roof perimeter

March 8, 2015

This weekend we finished the insulation to the roof perimeter. First came the preparations...


We tried a few different ways to begin with, but finally settled (after reading a tip on Bill Butcher's blog about the Green Building Store's Golcar project) on filling the web of the JJI roof joists first, and then filling in the middle. We managed to use a lot of off-cuts for this job, which had come from the external wall insulation, so it became a good way to inadvertently 'tidy' the site!

Then we built up the joist depth with 3 layers of 100mm deep Steico Flex wood fibre insulation....


With a little help from some friends!


We had to come in to the space approximately 700mm at the most, in order to eliminate the thermal bridge at the roof / wall junction.


In some places we were left with really narrow gaps to fill, so again the off-cuts and 'waste' from previous cuts came in handy!



Similarly, there were narrow gaps to fill over the internal wall heads...


Around the double height space...

The finished ceiling...

We have two locations where the airtightness layer has to go up into the rafter depth to accommodate services: one for the sprinklers, and one (shown here) for the soil vent pipe and solar thermal pipework. With hindsight the Bauder roof system is so good that we could have taken the SVP up through the roof with no concerns, but at the time we were worried it could present a potential leak point given how flat our roof is. So instead of simply rising vertically, we are taking ours out further along the elevation. More on this in a later post, but this is the airtight 'box' we formed with the Intello membrane to allow this to pass into the rafter zone as we do not have a lowered ceiling out-with our inner 'box' so the pipe needs to be fully above the ceiling line.