As we used a builder in an extension we had done a few years back we have spent the last 18 months rectifying cock ups he made of jobs he did not do right. The next one is to take down the plaster board and tape the Kingspan insualtion that he did not do as the draughts blowing through the ceiling lights means the house is always freezing 10 months of the year. Advice on what tape to use and stay stuck indefinitly would be great
You need the foil tape (screwfix/toolstation/wickes etc)
The best stuff is the stuff that doesn't just come off the roll like Sellotape, it has paper that you need to peel off to expose the sticky bit. That stuff sticks forever, even on dusty surfaces (which they always are)
The other stuff comes off almost straight away.
If needed, I'd close all gaps between insulation boards with expanding foam before taping up, around edge too between insulation and brickwork. The tape is to act mainly as a vapour barrier. If you have just the tape with a gap behind you will still have a cold bridge, though you will have solved a draught, which needs doing. All this sounds a bit drastic though, have you tried just using filler where the wires come through, and are you sure the insulation is gappy and untaped?
Cheers guys - yep unfortunately it is a bit drastic as it is an area of about 20 sq metre of plasterboard that needs to be brought down and taped, also the three Velux windows fitted leak when the wind blows from the north.
Tape across every joint and expanding foam in every gap. I was complemented by building control on my workshop, apparently most builders don't bother taping and leave gaps everywhere. Mine was airtight when I finished.
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