cavity wall insulalation and doubleglazing

suered

Hi all

A question for you. If, in the process of installing doubleglazing, a significant amount of cavity wall insulation beads were to escape, what would be the correct way forward?

Thanks

Furts

Not an official approved method, but I would suggest expanding foam applied by gun to hold the beads in place.

This could cause wet to bridge across the cavity so should be done with care and understanding.

I did a similar approach with the vertical dpc when my windows were replaced - though at that time there were no beads in my cavity.

Be aware any work or disturbance to the beads makes your 25 year insulation guarantee invalid. But you are probably too late to need to factor this is.

Whether the guarantee, or the organisation "CIGA," is of any use to the vast majority of people would be a separate post!

suered

Hmm. The insulation was done before my ownership. Windows were put in yesterday and there was some escapage. In one in particular when you looked in the cavity it was very noticeably empty/beads/empty.

Should the doubleglazing firm be put on notice that if future damp problems occur I will hold them responsible or are they likely to say escape of beads is not their problem? Has anyone else ever had this happen? (They are returning next week to plaster around windows).

Oh - and another question if I may - how much foam would you expect down the side of the windows? i.e. between new frame and actual wall opening once old sash removed?

Thanks

Furts

With regard foam at the sides the principles are;

the windows are typically about 2-3mm smaller than the opening on each side (it depends on the colour and the overall opening etc.)

The windows should receive approved fixings into the opening - foam is not a substitute for proper fixings.

The windows should receive a full sealant seal to the outside face and also to the inside face where they abutt the walls.

The fitters are responsible for doing a proper job on your home - this includes protecting and making good the cavity fill as best as possible. There will be some vagueness here because the beads may well tumble out of the opening, but they should have a method statement and plan of work to try and prevent this.

suered

Furts, thanks again. The casement replacements seem fine, but some are box sashes turning into casements - they have one centimeter plus of foam in places........??? I did ask the fitters about the beads and they said they could inject some foam but if that bridges the cavity..........

I will try and get a pic later when mate comes round with smart phone.

Furts

The 1cm foam is likely to be OK. When windows are fitted in older openings these openings are often variable or inconsistent. However if it is a regular 1cm this is not so good. This suggests poor measuring or a window not sat centrally in the opening(?) Either way one could argue does it matter provided they end up securely fixed, properly sealed and neatly finished on the inside (which might be an issue if there is a 1cm foamed gap).