Covering window cavities, how and does an inspector need to see?

[untrepid]

Hi, new extension build and I'm left with window openings still showing all the wall cavity insulation, nothing blocking the bottom and sides (lintel on the top).

My plasterer says he sometimes just covers the side gaps with a decent blob or plaster adhesive against the outside brickwork and it usually holds just fine. Alternatively use expanding foam to fill the gaps and then cut to fit.

What's the recommended way around these parts to bridge a 11cm cavity, with little to no ledge on the outer brickwork due to the windows being flush with it. I've already heard formal cavity closers are mostly an overpriced gimmick?

AND... does a building inspector care about seeing it beforehand or can I just go at it immediately? To prove the cavity insulation is there etc..?

 

[noseall]

I make my own closers using 100mm Celotex, dpc and foam. I use plasterboard nails to pin the dpc to the Celotex then friction fit them into the cavity, using Celtex wedges if necessary. Then I just foam all the gaps. I will also flatten the end of the (plastic) foam nozzle for those tricky tight gaps.

 

[noseall]

AND... does a building inspector care about seeing it beforehand or can I just go at it immediately? To prove the cavity insulation is there etc..?

Inspecting cavity closers is not part of their usual checking process. They will think you are barmy asking them out to check closers. Take a photo for your own record.

 

[THughes]

I've just ripped down a conservatory i built 10 years ago with cavity closers around all openings. They were the last thing holding the walls together after the digger took a bite.
(i personally wish i did a poorer job as is took 3 skips to clear)

The plastic strips slip into the 3-5 mm gap between the window frame and brickwork perfectly and all that is needed is a drop of grip fill and a few clout nails on the inside edge to finish. Far more secure than celotex alone in my view and the additional cost it easily covered by time savings.

 

[noseall]

Far more secure than celotex alone in my view and the additional cost it easily covered by time savings.

You have obviously not had to fix plasterboard to a wafting proprietary cavity closer then. A reet pain in the bum and very difficult (time consuming) to remedy, without ripping them out.

When mine are foamed in you could give them a good punch with your fist and they won't budge.