Green Building Forum - Stud bay window insulation

Stud bay window insulation

Osprey — Mon, 23 Jan 2023 19:02:27 +0000

I have a large, curved bay window in my bedroom. The stud wall beneath is also curved, as is the large skirting board. I would like to add insulation, but am loath to make a mess, have to move the skirting board and attempt to change its curve etc.

I was wondering if I could simply make a hole (in each stud partition) and pour in EPS beads. Then fill the holes, job done? I would prefer to use the grey, cavity wall beads, but they seem almost unobtainable, so could I use white beads?

The outside of the bay wall is rendered (pebble dash, good condition) and the inside is very good condition plaster/paint.

Any thoughts on whether this would be a good or really bad idea welcomed!

Stud bay window insulation

WillInAberdeen — Mon, 23 Jan 2023 21:17:08 +0000

As it happens I did that job before Xmas. Our bay has 5 window panes, so I glued 5 pieces of PIR to the inside of the wall, so that the joins line up with the panes above. Then 5 pieces of plasterboard glued on top and taped/filled to look vaguely professional. I couldn't reuse the skirting so fitted 5 lengths of new, cut to angles to fit, then trimmed the carpet back to fit.

While at it, I lifted the floor and insulated underneath, surprisingly big void under there.

All in all it was a lot of faffing to insulate a fairly small area, but it had been the coldest surface in the house so attracted condensation and mould. Now much improved.

Your method sounds a lot easier, I wish ours was a stud wall!

Stud bay window insulation

tony — Tue, 24 Jan 2023 09:13:16 +0000

I have a blower gun that will blow beads into the void. Has been used to fill old TF panels like yours before

Agree about the floor void

Stud bay window insulation

Osprey — Tue, 24 Jan 2023 14:14:45 +0000

Thanks for replies. Will, yes that's eems the way for solid walls, but much mess. (I have space under windowledge for probably 50 mm of IWI on the inner face of the bay, but mess, hassle, skirting board...)

Tony: A proper blower gun would be handy, but I am assuming the space between battens would not be great, and gravity, plus maybe a vacuum cleaner on 'blow' would suffice...

Any thoughts on use of white beads (eBay bean bag fill type) and lack of any vapour barrier?

A hole in the wall + borescope to check the 'floor' situation is planned next.

Stud bay window insulation

tony — Wed, 25 Jan 2023 21:55:38 +0000

Beads are vapour open, but I like vb on warm side on insulation to act as an air barrier too.

I would fill the voids full and yes a vacuum cleaner on blow will work.

Stud bay window insulation

Osprey — Thu, 26 Jan 2023 13:52:22 +0000

Posted By: tonyBeads are vapour open, but I like vb on warm side on insulation to act as an air barrier too.

I would fill the voids full and yes a vacuum cleaner on blow will work.

Thank you Tony!
(I take it white eps beads are better than no beads at all!)

Stud bay window insulation

tony — Thu, 26 Jan 2023 14:39:57 +0000

Yes,