Tue, 06 Oct 2026 02:02:10 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309438#Comment_309438 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309438#Comment_309438 Mon, 06 Oct 2025 15:46:14 +0100 Victorianeco
https://drive.google.com/file/d/12ZZsoLmjjSMoA4AW8HBQ_oQzmi9waWuE/view?usp=drive_link

Obviously this is a thermal bridge and we'd like to engineer it out.

Option A
Remove pillar - replace with a structural beam, disc out all cavities around window openings and fit cavity closures. Then EWI.
Appears to be messy, labour intensive, minimal gain?

Option B
Just install new windows outside of external skin, EWI over pillar and walls - and be done. Perhaps not as thermally efficient but cheaper, faster, less mess?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309439#Comment_309439 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309439#Comment_309439 Mon, 06 Oct 2025 16:28:51 +0100 fostertom
Always assuming the cavity isn't somehow a conduit for outside air into the interior - now there's a thermal bridge for you!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309440#Comment_309440 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309440#Comment_309440 Mon, 06 Oct 2025 17:18:50 +0100 djh Posted By: VictorianecoJust install new windows outside of external skin, EWI over pillar and walls - and be done. Perhaps not as thermally efficient but cheaper, faster, less mess?Sounds like a plan.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309441#Comment_309441 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309441#Comment_309441 Mon, 06 Oct 2025 20:25:31 +0100 Victorianeco
Now it's a case of final decision of tilt and turn or outward opening.

And then double or triple glazing ?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309442#Comment_309442 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309442#Comment_309442 Mon, 06 Oct 2025 22:19:50 +0100 Peter_in_Hungary
2G or 3G - budget constraints, exposed location, noise mitigation and window size all come into the decision making. For a large window perhaps 3G is justified especially in an exposed location. I usually go for 2G unless other factors come into play e.g noisy environment or exposed large window.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309443#Comment_309443 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309443#Comment_309443 Tue, 07 Oct 2025 09:07:56 +0100 LF
I've installed some 2g and 3g glazed upvc this summer - very pleased with result. We are getting to end of the work now.

Even get condensation on outside of double glazed - need to thermal scan them when it is a bit colder.

Just touching the glass and reveals it is much warmer than rest of house which is reasonable 20 odd year old upvc 28 mm double glazing without thermal edge enhancement of modern stuff, they are softcoat.

I am sure I got supplier from on someone on here, modernupvcwindows. I visited them first and have been pleased. Good value.

One window 2.2 m wide triple glazed with a small opening window on the end that opens outwards - see photo.
Installed so some of frame covered from inside - I added insulation then had it skimmed.

We have a sliding window (actually door) that is 2.8 m by 1.7 m with a window seat under. That had to be double glazed.
a triple glazed full length glass door 1m wide. Very good quality - friend asked if it was Velfrac.
It is black and when open gets the sun and needed glazing packers adjusting a couple of times. Really air tight frame.

We cut the bricks that bridged the cavity and insulated the cavity, the windows bridge the cavity about 30 mm in.

A lot of work - so fitting on outside in your new insulation layer sounds potentially a lot better.

I will add some pickies later struggling to add at the moment.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309449#Comment_309449 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309449#Comment_309449 Tue, 07 Oct 2025 19:11:03 +0100 Victorianeco https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309463#Comment_309463 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309463#Comment_309463 Fri, 10 Oct 2025 07:42:53 +0100 LF
Enough space to get beads off but reduces the impact of frame. (and makes it warmer) Insulated boards (backer type) fixed on with flexifoam on top of the cavity closures. Many I could only get 20 mm thick board on. It skims over well - plasterer was happy.

Air tightness tape from window to on side of cavity closure and from other side of cavity closure to wall.

Window seat window is sliding door - double glazed. Fixed as above.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309464#Comment_309464 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309464#Comment_309464 Fri, 10 Oct 2025 09:03:51 +0100 fostertom Posted By: LFnough space to get beads off but reduces the impact of frame. (and makes it warmer)Always good to 'bury' the width of the fixed frame, in as much insulation thickness as possible, at the jambs, both internally and (if you're doing EWI) externally. It makes a surprising difference to the effective overall insulativeness of any window.

Or, if you can't do the 'burying' with insulation (because it's all made of plasterboard/backer board etc internally, or of cladding material externally) it at least hides the excessive width of most modern fixed-frame sections.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309484#Comment_309484 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309484#Comment_309484 Sat, 11 Oct 2025 11:40:41 +0100 LF 2 layers of 20 mm in some places.
One sheet of 10 mm also used.

Not as rigid as plasterboard so a bit more fiddly to get flat.

Blue flexifoam used to stick it in place.

Pretty hard to burn, goes out quite quick.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309485#Comment_309485 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309485#Comment_309485 Sat, 11 Oct 2025 11:49:11 +0100 fostertom
Given the narrow width of reveal boards, I'm surprised you find such narrow plasterboard strips significantly easier to get flat? On the other hand, in an old house, maybe we''re looking for ways to reproduce a bit of waviness, tho plasterers will find a way to make it severely flat, whatever you do!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309486#Comment_309486 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309486#Comment_309486 Sat, 11 Oct 2025 16:24:28 +0100 Victorianeco
Even though the windows would be mounted within the EWI layer the depth from outside to insure becomes quite large.

Has anyone noticed this particularly on smaller windows ~2m2 of obscuring the angle of view?

Really starting to doubt if the labour, cost and benefit is really that great as I'm assuming heat pumps will likely improve all even further in the future]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309488#Comment_309488 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309488#Comment_309488 Sat, 11 Oct 2025 17:28:50 +0100 djh Posted By: fostertomtho plasterers will find a way to make it severely flatI was very pleased when my plasterer asked me how smooth/flat I wanted the finish Smooth but not completely flat was my answer.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309489#Comment_309489 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309489#Comment_309489 Sat, 11 Oct 2025 17:34:58 +0100 djh Posted By: VictorianecoEven though the windows would be mounted within the EWI layer the depth from outside to insure becomes quite large.

Has anyone noticed this particularly on smaller windows ~2m2 of obscuring the angle of view?Our windows are mounted nearer the outside for that reason, as will be yours. Deep window boards are a useful feature; we can sit on one in the living room that is low enough.

Our interior reveals are curved back a bit, which helps the view and lightness of the openings. The exterior can be curved back as well but ours was kept right-angled for aesthetic reasons.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309490#Comment_309490 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309490#Comment_309490 Sat, 11 Oct 2025 19:36:40 +0100 fostertom Posted By: Victorianeco120mm EWI for my projectWhy only? you'll save £ peanuts, as insulation boards' cost is the least of it, you're not constrained by narrow side path, and eave and verge overhang is generous.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309491#Comment_309491 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309491#Comment_309491 Sun, 12 Oct 2025 16:09:16 +0100 Victorianeco
Why go more? reduce the angel of view from the windows, how many days a year heating will it really save?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309492#Comment_309492 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309492#Comment_309492 Sun, 12 Oct 2025 18:25:53 +0100 fostertom Posted By: VictorianecoThat would get me to Enerphit Levels of ~0.15 for the wallsThat must be because you have wide cavities well CWI'd? I must have missed that. If so, then yes, 120.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309494#Comment_309494 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18360&Focus=309494#Comment_309494 Sun, 12 Oct 2025 19:02:47 +0100 Victorianeco