Green Building Forum - Internal Wall Insulation - what about the returns? Mon, 18 May 2026 08:42:13 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178712#Comment_178712 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178712#Comment_178712 Wed, 26 Jun 2013 23:55:46 +0100 athomson
My question refers to the return of this insulation on the inside walls. The insulation manufacture (NBT - Paventro) recommends a return on to the inside walls for 600mm. A potential installer has suggested 40mm of woodfire on these returns in order to meet this reccomendation.

This, obviously, would look a bit odd. Rooms with stepped walls, with additional insulation encroaching on the reduction on the room size.

Has anyone else installed iwi. What did you do with the returns, if anything?

Would insulated plaster be sufficient. Say, 20mm of Diathonite - http://newton-membranes.co.uk/diathonite-insulation-plaster/ - instead of the 40mm of woodfibre?

Any thoughts/experience would be appreciated.Thanks.

This]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178713#Comment_178713 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178713#Comment_178713 Thu, 27 Jun 2013 00:26:43 +0100 Saint Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178720#Comment_178720 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178720#Comment_178720 Thu, 27 Jun 2013 08:26:02 +0100 fostertom
Tapering it does recognise the diminishing temp difference that exists, as you come inboard. You can start it at the full 60mm.]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178721#Comment_178721 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178721#Comment_178721 Thu, 27 Jun 2013 08:26:43 +0100 fostertom Posted By: Saintmodelling on hygrothermal softwareWas that WUFI 2D?]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178724#Comment_178724 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178724#Comment_178724 Thu, 27 Jun 2013 08:34:45 +0100 davidfreeborough
An alternative approach would be to put a thermal break into the internal/partition wall where it meets the external wall. However, before cutting a vertical slot into the internal wall, you would need to confirm whether any structural restraints would be required, e.g. wall ties.

Will you be removing the existing plaster before starting work?

David]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178725#Comment_178725 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178725#Comment_178725 Thu, 27 Jun 2013 08:35:57 +0100 jamesingram Found several walls to be stud, lath and plaster so just cut out and slotted the 40mm through.
The rooms where quite higgle-piggly so in some instances covered the whole small return wall in 20mm to avoid a step.]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178728#Comment_178728 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178728#Comment_178728 Thu, 27 Jun 2013 08:50:14 +0100 Saint Posted By: davidfreeboroughThe end of the insulation return nearest the external wall should be at least as thick as the internal wall insulation.
David, strangely perhaps, that's not what the hygrothermal modelling showed. The difference is marginal using various thicknesses. Length along the wall has a far greater impact although as usual the Law of Diminishing Returns has a play in this]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178729#Comment_178729 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178729#Comment_178729 Thu, 27 Jun 2013 08:59:28 +0100 davidfreeborough
David]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178731#Comment_178731 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178731#Comment_178731 Thu, 27 Jun 2013 09:25:53 +0100 fostertom
My recent experience with WUFI shows many surprises - both counter-intuitive ones, and surprises as in upsetting the rules-of-thumb that I've been relying on! Big re-think in progress - but generally liberating rather than constricting. WUFI (or Delphin maybe) looks to be indispensable for future work.]]> Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178735#Comment_178735 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=178735#Comment_178735 Thu, 27 Jun 2013 09:34:43 +0100 Saint Internal Wall Insulation - what about the returns? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=179009#Comment_179009 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10831&Focus=179009#Comment_179009 Mon, 01 Jul 2013 10:29:43 +0100 athomson
Yes - the original plaster will be removed prior to starting.]]>