Green Building Forum - (Rock) Mineral Wool - Water Uptake Tue, 19 Dec 2023 07:58:49 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 (Rock) Mineral Wool - Water Uptake http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263708#Comment_263708 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263708#Comment_263708 Wed, 06 Dec 2017 18:30:42 +0000 Doubting_Thomas
I've used it in this arrangement for brickwork cavity walls before and then placed something like XPS in the below DPC area. My current timber rainscreen detail (below) therefore swaps out the lowest band of Rockwool for a 350mm plinth of XPS in the knowledge this is less permeable.

How paranoid am I being, though? It would be far simpler to take the same insulation all the way to ground, but clearly I'm keen to not build in a recipe for damp further down the line. Particularly with a timber internal structure.

NB. external ground levels will slope away from the building more than is shown here...]]> (Rock) Mineral Wool - Water Uptake http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263713#Comment_263713 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263713#Comment_263713 Wed, 06 Dec 2017 21:29:56 +0000 djh
I would think you want the DPM/DPC under the floor level, otherwise how does an indoor flood escape?]]> (Rock) Mineral Wool - Water Uptake http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263717#Comment_263717 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263717#Comment_263717 Thu, 07 Dec 2017 08:05:58 +0000 TimSmall (Rock) Mineral Wool - Water Uptake http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263723#Comment_263723 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15438&Focus=263723#Comment_263723 Thu, 07 Dec 2017 11:37:31 +0000 Doubting_Thomas
Posted By: djh
I would think you want the DPM/DPC under the floor level, otherwise how does an indoor flood escape?


I've got a Radon barrier membrane below the concrete structural slab (admittedly not as shown on the drawing as I subsequently moved it from above slab to below) to stop rising water. Had been planning just a bonded screed on top of the slab but you're implying another thin membrane below the screed may not be a bad idea.

The thing is there's now grout below the CLT wall around the perimeter so any substantial water build-up internally would be fairly well contained anyway - I've been more concerned about keeping air from leaking out than how to get rid of internal water.

Externally, anything that got through the breather membrane (blue) & 400mm of Rockwool should hit the airtight vapour-check membrane wrap (dashed red layer) outside the CLT and be directed down to the concrete (we are butyl sealing the membrane down to the slab). My concern was that once it gets to the concrete it could be 'held' by the rockwool whereas XPS might be more hydrophobic and thus the water would be shed.]]>