Window board on cavity wall

[antsbradley]

Hi,

Just fitting out new extention, and wondering how best to put in window boards. Have UPVC windows in outer brickwork with no rebate / lip, and blockwork inside, so I can only affix to the blockwork with no physical support at the window edge.

I read on another post to maybe use plasterboard first to bridge the gap, then put wood on top of that, is that correct, or should the wood go straight onto the blockwork?

Is it ok to use somthing like Pinkgrip to bond the wood / plasterboard to the blockwork or should it be plugged and screwed? Either way I was thinking of also pinkgripp'ing the board edge to window also, to give a little more support?

Many thanks

Anthony

 

[noseall]

first, we fix cavity closers to the cavity prior to the windows going in (as in most closers part of the closer dpm sits between the upvc and the brickwork).

we then dab some 12.5mm plasterboard to the reveals. this can be tapped perfectly level.

once set we than use either 'stixall' or 'sticks like s**t' to fix the window board to the plasterboard. these two products are far superior to most adhesives as they will still grab even in damp conditions.

 

[antsbradley]

The builders put foam cavity fills either side and at the top, but nothing in the bottom, and the windows are all fitted now so I guess its a bit late to change it (the building inspector was happy with what they had done).

So question is whats best to do now that we dont have the benifit of a closer for it to sit on, can I just bond some plasterboard to the blockwork and the edge to the UPVC, and then bond the windows board onto that?

thanks

Anthony

 

[noseall]

you could still fix a cavity closer only it wont have some bits tucked behind the window.

i think cav' closers are overpriced anyhow.

any rigid insulating material would do i.e. polystyrene cut to size, friction fitted and glued into place.

 

[Thermo]

i think cav' closers are overpriced anyhow.

.

thats an understatement!

 

[^woody^]

I can't see the need for plasterboard. The window board will bridge the cavity and will be fixed the same as the plasterboard would be

Close the cavity with some expanding foam or normal insulation, and then either gripfill, or screw and plug the window board down. It will not be going anywhere

 

[noseall]

the plasterboard can be fixed to the masonry using dry lining adhesive.

this provides a connection to the masonry that is almost unrivaled.

you then have a large surface area platform, that is perfectly level and true, upon which several blobs of high grab cartridge adhesive can be used.

the board can be lowered onto this platform with very little levelling - merely a press into place, et voila!

believe me, if there were a quicker more successful method i would use it. it is the strength of the bond of the relevant materials which makes this method so good. it is only when you have had to remove both that you realise the benefit of one over the other.

 

[noseall]

p.s.

adding a layer of dabbed 12.5mm plasterboard brings the window board more in line with the 'correct' margin around a upvc window sill.

meaning the margins around the sides top and bottom look proportional.

 

[^woody^]

Sold!

 

[antsbradley]

thanks for all the replies, I have a bit of celotex left over from the floor so will jam that to fit in the void and then plasterboard over that.

This forum is great!

Anthony