Breeze behind plasterboard

[V8RX7]

The latter - it's doing what a solid dab would do.

[skahigh]

Yeah, that's what I had expected the roofers to do, turns out that's a bigger job than they thought. I may get a builder to have a look instead, roofers didn't seem keen.

Anyone any thoughts on cavity wall insulation? There's so much conflicting information about.

[anonymous-user]

It sounds like cavity wall insulation won't fix your specific problem if I am understand you correctly.

To confirm, you have plasterboard dot and dabed onto the external wall? Gap at the top between the plasterboard and the inner leaf is open? You need to seal the top and bottom of the gap between the plasterboard and blockwork. When dot and dabbing you should run a continuous bead of bonding at the top and bottom and dabs in the middle. That is how it should be done, but often isn't.

Squirty foam and filler sound like the easiest way to fix. Sealing this gap shouldn't cause any damp issues - unless there is a specific problem with the wall (like leaking gutters etc).

[skahigh]

It's battened rather than dot and dab.

The gap at the top is only accessible by taking about three rows of tiles off which also involves disturbing two velux windows, hence why the roofers didn't seem keen.

[anonymous-user]

Ah ok, that all makes sense now. You options are still the same though. Access from tiles and fill or drill holes and carefully foam. As mentioned before, cavity wall fill won't sort this issue. It will help in the end, but if cold air can still get in between the plasterboard and block the wall will still feel cold and lose heat.

[jules_s]

Skodasupercar said:

Ah ok, that all makes sense now. You options are still the same though. Access from tiles and fill or drill holes and carefully foam. As mentioned before, cavity wall fill won't sort this issue. It will help in the end, but if cold air can still get in between the plasterboard and block the wall will still feel cold and lose heat.

If its a cold roof and there's a gap they should be able to seal the void from above.

Sounds like a continuity issue as well though

[skahigh]

Thanks guys, sounds like blowing some kind of insulation / seal in through holes in the plasterboard is going to be the way to go.

Is expanding foam or rock wool a fire risk at all with electrical cables behind the plasterboard?