What should first (top) floor UPVC windows be attached to at the top?

[Beginerz]

Most of them probably. But in your case adding it makes sense, as it closes the gap and reduces a bit of heat loss/cold spot. Your walls (assuming 60s?) wouldn’t have been insulated originally either, just a clear cavity.

There is sprayed in cavity wall insulation in the walls from around 2000 I believe. Found it to be there within the cavity when knocking back a downstairs window.

Ideally there would be insulation behind it rather than a gap; if you're talking about the vertical sides to the window, insulation backed plasterboard bonded on with foam would be best. For other areas, if there is a chance it will be exposed to draught, rigid foam may not be best. Though wool doesn't perform as well a PIR/PUR in a lab, it is easier to fit and deform around awkward shapes leaving less opportunity for draughts to reach the plasterboard. Of course, rigid would work well if it can be guaranteed sealed up to be draught free but doing so can be really fiddly and time consuming in restricted space

What could be used to stick the wool insulation in place where I need it?

 

[robinbanks]

When you say "stick" do you mean glue/adhere or do you mean push/place/insert?

 

[Beginerz]

When you say "stick" do you mean glue/adhere or do you mean push/place/insert?

Glue/adhere.

 

[robinbanks]

Wool normally just stays if the adjacent surface has any measure of roughness to it. Cavity 100mm? 150 thick wool sandwiched between two sheets of thin plastic and compressed, inserted into gap, withdraw one sheet leaving one side of wool in contact with cavity, then withdraw the other sheet, wool expands to fill and stays put..

Anything slippery smooth can be used as an aid to wool placement, ply with visqueen stapled to it etc.

 

[Beginerz]

Wool normally just stays if the adjacent surface has any measure of roughness to it. Cavity 100mm? 150 thick wool sandwiched between two sheets of thin plastic and compressed, inserted into gap, withdraw one sheet leaving one side of wool in contact with cavity, then withdraw the other sheet, wool expands to fill and stays put..

Anything slippery smooth can be used as an aid to wool placement, ply with visqueen stapled to it etc.

Perhaps the outer skin facing sheet of plastic could remain to act as a vertical DPC on the absence of one?

 

[robinbanks]

Good plan. Even better if one can get a whole good sized sheet of Visqueen in there for a continuous barrier

 

[catlad]

Welcome to improving your new home from the 60s? they were not bothered about insulation then , The timber above your window could be the wall plate. If you are fitting new windows I would consider making the aperture smaller to accommodate more insulation around the new windows.

 

[Beginerz]

Good plan. Even better if one can get a whole good sized sheet of Visqueen in there for a continuous barrier

Some definitely might go in probably not at lot though due to the sprayed in insulation lower down in the cavity. If needed is there an adhesive which could assist in sticking visqueen to bricks?

Welcome to improving your new home from the 60s? they were not bothered about insulation then , The timber above your window could be the wall plate. If you are fitting new windows I would consider making the aperture smaller to accommodate more insulation around the new windows.

Quite right 60s indeed.

I plan to try my best to get insulation in there without having to knock all of the plaster out. Is this going to be possible?

 

[robinbanks]

If needed is there an adhesive which could assist in sticking visqueen to bricks?

Nearly nothing sticks to it, but it won't be needed anyway


Just knock the plaster out and make good after, make your life easy

 

[noseall]

Nearly nothing sticks to it

We've has success with the better polymer type adhesives i.e. CT1, Hippo Pro, OB1 etc.

but it won't be needed anyway

Agree.

 

[robinbanks]

I've stuck it with OrconF, and the double sided bituminous looking stuff for radon barrier, but didn't want it to be misconstrued as a recommendation..