Expanding foam around window

[5oysterman2]

Morning chaps, got a plasterer round tomorrow to skim walls & ceiling's. I took the trims off this morning & noticed the gaps around window were quite large. I was hoping not to put trims back on & just paint upto the window itself.

If I fill the gaps up with foam, will that be a hindrance or a help to him. Thanks for any replies

 

[Lower]

I'd foam them so that the window is properly sealed and insulated. He can then skim over the top.

 

[ETAF]

have a look at the foam you buy , there is one for things like frames , windows - that does not expand as much
i have used both - 1 on windows , others with a gap around a plastic roof - long story, but that cause all sorts of issues as it expanded , what seemed like forever at the time, distorting....

 

[thomp1983]

Get a metal foam gun, you will get a far neater job as you can turn it down to only apply the right amount which then won't expand crazily.

Tape the frame and plasterboard before foaming so any mess comes off with the tape

 

[mrrusty]

Put the trims back on. Thermal coefficient of expansion of uPVC is horrible - 0.06-0.08mm/degree/m so a 1.5m wide window will potentially expand/contract from winter (say -5deg) to summer (say +25) 0.07 x 1.5 x 30 = 3.15mm. The trims fixed to the wall and not the frame, cover up the thermal movement. If you try plastering right up to the window all you get is a permanent crack.

 

[5oysterman2]

Get a metal foam gun, you will get a far neater job as you can turn it down to only apply the right amount which then won't expand crazily.

Tape the frame and plasterboard before foaming so any mess comes off with the tape

Wish i had got a gun now Thanks for the tip about tape thou, i forgot how messy it can be.

 

[5oysterman2]

Put the trims back on. Thermal coefficient of expansion of uPVC is horrible - 0.06-0.08mm/degree/m so a 1.5m wide window will potentially expand/contract from winter (say -5deg) to summer (say +25) 0.07 x 1.5 x 30 = 3.15mm. The trims fixed to the wall and not the frame, cover up the thermal movement. If you try plastering right up to the window all you get is a permanent crack.

Cheers mrrusty, never gave that a thought.

 

[thomp1983]

Gun pays for itself first time you use it and you can normally leave the rest of the can fitted to it until you next need it aslong as it's not months and months