Thursday, 22 November 2012

airtight?

Building a low energy home requires us to do a number of things....
An obvious and simple thing is to wrap it up so that no heat escapes - and our home will indeed have extra thick layers of insulation under the floor, on the walls and above the ceiling as well as triple glazed windows.
And there's the heat generation of an air source heat pump to warm the underfloor heating and to heat the water.
Conventional mortar joints lose a home 25% of its heat: our mortar joints are skinny!
But most homes leak heat through lack of airtightness, through windows, doors, cracks and cavities. Our aim is to eradicate every leaky hole and achieve level 1 air tightness - the highest level. To make sense of this, we need to reduce all the little holes to the total area of one side of a 5p piece! A huge challenge.
fuzzy photo of man applying tape to trusses
And to achieve this we have to create an airtight envelope around our living spaces that isn't penetrated by wires, pipes or even pin pricks.
We've considered many methods with our builders Newtec and our architect Mike Ellison. It was Steve, our builder, who had spotted a Swiss airtightness product made by Siga on Channel 4 Grand Designs. Training was arranged and we bought the products: highly adhesive tapes holding a flexible membrane in place.
And today that work started on the ceiling - apply 'Twinet' tape to fifty roof trusses onto which we will stick the 'Majpel' membrane. where the 'Majpel' overlaps, joints will be closed using ''Sicral' tape. 'Majpel will overlap down the walls and be stuck with 'Primur'.
After this, battens will be screwed onto the trusses and the adhesive witll close around the screw threads, making that puncture airtight.
When services have been brought in, plasterboard will be screwed into place and the ceiling will be ready for a finishing skim of plaster. The latter stages will be done by professionals!!


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