insulating window reveals

[MartC]

I've come to realise that our 2001 vintage house is a little bit of a plasterboard tent, and I I have a hundred questions to ask about trying to improve it, but I will start with one.

 

My immediate question is about insulating window reveals. We have a few replacement windows on order, to replace some failed ones, and the thermal camera shows many reveals are cold.    

Can I just ask the window installers to fill any gaps behind reveals with foam or insulation when they remove the old windows, or is there any reason I should not do that, if they agree? Foam would be more airtight but might bulge plasterboard, and rockwool might be less effective.  I know it'd be better to rebuild them from inside, but that's probably beyond my DIY skills and I'd need to get someone in to do that, so it'd not an immediate prospect.

 

Thank you! 

 

 

[RobLe]

I’m a big fan of expanding foam in any gaps, having used it all over the place!  Having said that, any piccies ?

I’ve never yet seen a big standard window fitted in a thermally effective way; usually there’s big gaps all round with a bit of trim and silicone so you don’t notice.  
Do you have condensation, or some other reason to attack the reveals ?

[bmj1]

We're using 25.5mm insulated plasterboard in our reveals (17mm PIR + 9.5mm plasterboard)

 

Given we've got sash windows with wide frames, this works nicely visually, and provides a good airtight finish.

[Russell griffiths]

You said you want to improve the insulation in the house, and start with the window reveals. 

You have pointed out the correct answer, but don’t want to do it. 

Im afraid if you want to improve it then you are going to have to bite the bullet. 

Rip of the plasterboard around the reveals. 

Get the windows fitted, then either fit insulated plasterboard or a board like jacko board, get all gaps foamed up and get it re plastered. 

[Iceverge]

Illbruck IL330 is the stuff you want in the foam department. 

[Mike]

11 hours ago, Iceverge said:

Illbruck IL330 is the stuff you want in the foam department.

Illbruck FM330 also gets my vote.

[IGP]

I had a similar problem, don’t have the money to upgrade my windows for a few years but pulled all the reveals off during my renovation, finding large gaps with gushing cold air everywhere and the existing plaster just falling off when you touch it. 

I also had to have a wall under the window rebuilt now tied to existing walls, as it was weirdly sat closer to the external skin with a tiny cavity basically freestanding with huge gaps. I don’t know what they were thinking when it was built (1930’s). 
 

Illbruck FM330 to the rescue!