Green Building Forum - Window and doors in EWI Thu, 24 Sep 2026 13:24:08 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Window and doors in EWI https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311577#Comment_311577 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311577#Comment_311577 Thu, 24 Sep 2026 07:36:57 +0100 englishjohn
Is there any reason why, to support the window/door, it couldn’t sit on a 4x2 or 4x3 CLS timber plinth that is screwed back into the existing cavity wall leaf, with some steel brackets up the sides?

Air tightness tape etc. all round and then encapsulate it all in the EWI, which in my case will be 200mm thick.

Wouldn’t this remove all the thermal bridging while making it very simple to deploy? Maybe I’m missing something or not appreciating the weight of the windows and doors sitting on the timber.

I also need to look at ordering windows, is Russel Tech Timbre still good value for money as I had a quote from 21degrees and can’t really afford them - more money was spent in the ground and rebuilding some walls ect than anticipated.]]> Window and doors in EWI https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311578#Comment_311578 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311578#Comment_311578 Thu, 24 Sep 2026 08:43:34 +0100 borpin
Windows are often fixed using metal plates fixed to the window then fixed back to the inner leaf. This offers numerous routes for air ingress.

The box is deeper than the window itself, ideally comes back inside to the depth of the reveal.]]> Window and doors in EWI https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311583#Comment_311583 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311583#Comment_311583 Thu, 24 Sep 2026 10:58:47 +0100 djh Posted By: englishjohnIs there any reason why, to support the window/door, it couldn’t sit on a 4x2 or 4x3 CLS timber plinth that is screwed back into the existing cavity wall leaf, with some steel brackets up the sides?The steel brackets are a large thermal bridge; and a timber plinth is a smaller thermal bridge. A ply box does away with both of them.]]> Window and doors in EWI https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311584#Comment_311584 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18479&Focus=311584#Comment_311584 Thu, 24 Sep 2026 12:53:38 +0100 fostertom Posted By: djhThe steel brackets are a large thermal bridgeDefinitely
Posted By: djha timber plinth is a smaller thermal bridge
yes, and can be made smaller still, I think, and as I'm offering to GBF collective wisdom, if done similar to my pic near the beginning, i.e. adapted as described a few posts later for extg masonry walling
Posted By: djhA ply box does away with both of them
Not entirely, and I'm saying not as well as the (more robust? easier?) way I'm describing. Trace the heat flow paths - am I wrong?]]>