Airtightness tape

Moggaman

Hi again. I have taped my windows over the last few days. I used Siga Fentrim which I found very user friendly and really bonded to the block work. the tape laps the window frame by 10mm and the spans the insulation to the block. I have metal straps -approx 3 on each side holding the windows in place put in by window supplier. These are fine for the most part but some sit out a little from the insulation. I am wet plastering the walls internally as my airtight layer. My question is .. is it possible to wet plaster the reveal or will it need plasterboard and then a skim?. I ask as some ( only some) of my taping either side of straps or where insulation is slightly shy of reveal has created flexibility in the tape- hollow areas behind tape… see photo below of typical bit of my work… this photo doesn’t really explain what I’m talking about . Perhaps I’ll get a better one later

thanks

cheers for advice

Biker1

https://www.boards.ie/discussion/2058224976/airtightness-tape

You must plaster the reveals as any bare block will result in air leakage. If you need to put plasterboard on the reveals to build them out to cover the tape on the windows that's fine.

Moggaman

Thanks.. u can plaster direct to the Siga Fentrim?

mickdw

I would typically use the tape with holes in the part that sticks to block as this helps with bonding to block.

Also' I'd add a patch of tape at each window fixing strap to cover them completely as they leak air there.