airtightness #3

Getting to all of those awkward places!

Lately we have been fixing the membrane to the first floor ceiling and tidying it up at the first floor junction which has involved lots of stretching and kneeling - sore limbs all round! Martin has mainly been working on fixing the Intello-Plus membrane to the ceiling (developing a nice crick in his neck as he goes!) - several thousand 10mm staples at 150mm centres later this is the result….

We have been leaving the perimeter for the moment as I still have to finally confirm one or two of the Therm details so that I can confirm the PSI value for this junction as there are 4 'scenarios' in total around our roof perimeter due to differing joist directions and different depths of rim beam. Unfortunately due to the parapet design we have to add a large amount of insulation internally of the rim beam to attempt to counteract the thermal bridging here. If we had been able to structure this junction slightly differently we could have possibly had a thinner layer of insulation externally as it would have been on the 'correct' side of the structure (i.e. the cold side) and would therefore have been more effective at countering the thermal bridge.

Whilst he was doing this I have been stapling up the membrane on the first floor to the Spano Durelis board, and forming a nice little taped web in the internal corners to continue an airtight seal here!

This detail was a little tricky but we decided to play it safe by creating a curved junction as this will be concealed within our service cavity zone (there is still a 30mm thick acoustic floor construction to go down on top of the chipboard before the first service cavity batten is fixed to the wall so most of this 'web' will be hidden in this zone).

The finished result at the intermediate floor.