OK to cut excess window fixing straps to help airtightness taping?

[Gaf]

Have seen these fixing straps referenced as often being a source of air leakage and reduced airtightness. Is there any reason I shouldn’t cut the strap after the affixing nails (red line) so there is less chance of them pulling up the airtight tape?

[Mr Punter]

One nail per strap looks a bit stingy.  Often see screws and plugs or masonry screws.  No issue with zipping off the surplus strap with a grinder and thin blade.

[Gaf]

56 minutes ago, Mr Punter said:

One nail per strap looks a bit stingy.  Often see screws and plugs or masonry screws.  No issue with zipping off the surplus strap with a grinder and thin blade.

Better to use screws on the last hole to both pin it flat and add extra strength to the strap? Throughout the house there’s at least one strap that has come loose.

[Mr Punter]

Yes, 50mm concrete screws are your friends here.  For a 7.5mm screw drill a 7mm hole and clear it out a bit so the screw goes in tight with an impact driver but does not lock up before it is home.

[carlos21]

1 hour ago, Mr Punter said:

Yes, 50mm concrete screws are your friends here.  For a 7.5mm screw drill a 7mm hole and clear it out a bit so the screw goes in tight with an impact driver but does not lock up before it is home.

thats what i did with mine, dont know about airtightness, but they are fixed in tight.

are you putting insulated plasterboard in the revels?

[Nickfromwales]

1 hour ago, carlos21 said:

thats what i did with mine, dont know about airtightness, but they are fixed in tight.

are you putting insulated plasterboard in the revels?

You can kill 2 birds with one stone and just use Marmox to line the reveals. It can be plastered directly, or you can PB and then plaster. Easier to do this without insulated PB as its a bit tricky to do this in straight thin strips imo.

[carlos21]

not seen that board before, looks versatile.  i was going to either render, then skim or dot n dab plasterboard then skim over the block walls, i wasnt going to add any internal insulation as the cavity has pir in. 

but maybe some insulation in the revels would be good.

[Nickfromwales]

23 minutes ago, carlos21 said:

but maybe some insulation in the revels would be good.

Essential, not just good!

[carlos21]

even in my case where from the back of the window frame, its cavity wall pir insulation then the internal block? if that makes sense.