Green Building Forum - Reducing thermal looping in an existing wall while preserving semi cavity Tue, 14 Jul 2026 14:23:12 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281213#Comment_281213 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281213#Comment_281213 Mon, 08 Jun 2020 13:58:21 +0100 wholaa Are there risks attached? Is expanded glass beads better?

___]]> Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281222#Comment_281222 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281222#Comment_281222 Mon, 08 Jun 2020 16:31:50 +0100 tony
I would use tiny beads if you can get them. Treat with pva, dry them, pour them in, they will stick themselves together after a while]]> Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281224#Comment_281224 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281224#Comment_281224 Mon, 08 Jun 2020 16:55:24 +0100 wholaa Posted By: tonyI think that you can buy small size beads 1 to 2mm in size rather than the more normal 4 to 8mm

I would use tiny beads if you can get them. Treat with pva, dry them, pour them in, they will stick themselves together after a while

Thanks Tony. There is no fire risk or anything of the sort?]]> Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281225#Comment_281225 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281225#Comment_281225 Mon, 08 Jun 2020 17:09:01 +0100 tony Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281232#Comment_281232 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281232#Comment_281232 Mon, 08 Jun 2020 19:45:08 +0100 djh Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281261#Comment_281261 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281261#Comment_281261 Tue, 09 Jun 2020 12:16:08 +0100 wholaa Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281272#Comment_281272 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=281272#Comment_281272 Tue, 09 Jun 2020 17:17:30 +0100 Mike1 Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=282695#Comment_282695 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=282695#Comment_282695 Fri, 07 Aug 2020 14:20:01 +0100 wholaa I was working on this window again. I tried to seal it with tufts of earthwoold and then poured in 1-2mm EPS beads. It's somewhat perilous as they are easy to inhale because they are extrodinary prone to being blow around. This makes them hard to work with but excellent for spotting draughts. When I had some windy weather I found it remarkable how clearly these beads could show windwashing of the insulation boards. See video

https://imgur.com/edvLFZN

https://imgur.com/QVeTG9g

I will have to just add a more glue and then seal with a windtightness or airtightness tape.
This window is on the windiest side of a very wind exposed house. There are some vents in the walls to vent the cavity see here
https://imgur.com/to7iXX2
https://imgur.com/5TMQuzc

But I wonder is there a formula to calculate how many vents are needed given local weather conditions? I wonder if I have too many and I could reduce the wind washing by blocking a few? I will also try to seal around my meter box too which is letting air in.]]> Reducing thermal looping in an existing wall while preserving semi cavity https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=282699#Comment_282699 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16594&Focus=282699#Comment_282699 Fri, 07 Aug 2020 18:13:37 +0100 djh Posted By: wholaaIt's somewhat perilous as they are easy to inhale because they are extrodinary prone to being blow around.
That's what face masks are for (among other things). :bigsmile:

There are some vents in the walls to vent the cavity

Are you sure they are vents rather than drains?

Sorry, I don't know how many there should be, except drains above every lintel etc.]]>