Which airtight tape is needed?

[ruggers]

Which airtight tape is best for window reveal cavity closers to blockwork?

 

I need to start buying air tight tape for various areas of the build, but first up, i need to order some asap to seal the plastic cavity closers to the internal block work reveals before the windows get fitted next week. 

 

I've just realised I'm going to need to tape one side of the closer before the frames go in. I'm having the frames set back into the cavity by 25mm, so window reveal fixing straps are being used, these will over lap the closer, meaning taping later wont make a decent seal.

 

Siga fentrim was suggested for some areas but its very expensive.

 

Just to add, all block work reveals are painted in airtight paint and closers will be modified to be thicker.