Tuesday, 20 September 2016

making a building airtight ..

We are getting our annex ready for the builders.

Those metaphors have been in an absolute whirl this week with all shoulders to the wheel, hands to the pumps and noses to the grindstone.  There's tiredness here, I can tell you evidenced by my admission that tonight, in addition to my dinner I have eaten half a box of Matchmakers, a mini-Magnum and two nectarines.

Ceiling Majpell goes up
Enough about my fallibilities.

In an eco-build the first and most-obvious element is insulation - put a warm jumper on. We finished our part of the annex insulation over the weekend: 25mm polystyrene sheeting cut and fixed to the inside of all exterior walls with plaster adhesive. Dirty, dusty work.

So, that was the jumper. But without a wind proof layer, the warmth of the jumper will be blown away - hence the need for airtightness.

It was Steve (aka 'The Great Man') who spotted SIGA airtightness products during a Grand Designs programme way back in 2012.

The Swiss SIGA system entails using rolls of fibreglass sheeting that have their joins taped to make them airtight.

And all those weeks and months of fixing Majpell sheeting to the insides of exterior walls and ceilings and use of excessively sticky tapes with names like Sicral or Rissan came back to haunt us.
Use of Sicral and Twinnet

Corner detail using Fcntrim and Corvum
But, we became quite good at the task when we built our house and in 2013 achieved the best score for airtightness that our examiner had recorded.

That was then - and it has taken some time to reclaim all those arcane techniques  and skills we'd previously mastered.  Some call it 'distance decay' - I call it plain forgetting.

But anyway, between the four of us we've almost finished.

Some tasks remain: the entries into the ceiling will be made airtight with Rissan tapes; the floor will be lined with black plastic sheeting that will wrap up the walls and be taped in place with Sicral. These will be undertaken during the building process.

Airtight walls and ceiling
I have one doorway to complete tomorrow. And then we can welcome the builders.




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