Green Building Forum - Installing Vapour control layer in timber frame garden room Tue, 19 Dec 2023 08:33:43 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Installing Vapour control layer in timber frame garden room http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301355#Comment_301355 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301355#Comment_301355 Wed, 26 Apr 2023 08:37:46 +0100 thebeacon
I have a question about how best to install a vapour control layer in the floor or my timber framed garden room.

The VCL will sit above the joists (with insulation between) and under 18mm OSB, which will form the subbase of the garden room. My question is, should the VCL be cut to the same size at the floor area, or should there be extra membrane left that can be folded back over the 18mm OSB floor?

If I installed the VCL with additional membrane, the wall bottom plate could sit on it and the extra membrane could be wrapped up the internal wall and fixed to the VCL I install in the wall. Would this make sense? The VCL that sits under the walls bottom plate would be punctured by the nails that fix the bottom plate in the subframe. Butyl tape could be used between the bottom plate and subframe to seal the nail punctures. My concern with using butyl tape is the thickness of it and I feel it would be better to have a solid contact between the bottom plates of the walls and the subframe.

I might be over thinking it all and it’s best to simply to install the VCL cut to the same size at the floor area.

I have attached two drawings to illustrate the build-up of the project.]]> Installing Vapour control layer in timber frame garden room http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301357#Comment_301357 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301357#Comment_301357 Wed, 26 Apr 2023 10:49:44 +0100 djh
If you fit a VCL, it needs to be continuous, so the first drawing is no good.

VCLs tend to be self-sealing around nails or screws, so no need to worry too much. How will the floor be secured to the joists?]]> Installing Vapour control layer in timber frame garden room http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301360#Comment_301360 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301360#Comment_301360 Wed, 26 Apr 2023 11:23:56 +0100 thebeacon Posted By: djhIs the garden room heated? yes it will be heated.



Posted By: djhHow will the floor be secured to the joists?
I will screw the plywood boards to the joists. So i don't need to butyl tape every joist.

Do you think its best to allow for additional to fold back over the floor, under the bottom plate, and up the internal wall and join it to the interior wall vcl?

or is there an alternative i should consider?]]> Installing Vapour control layer in timber frame garden room http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301361#Comment_301361 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301361#Comment_301361 Wed, 26 Apr 2023 12:03:22 +0100 djh Posted By: thebeaconDo you think its best to allow for additional to fold back over the floor, under the bottom plate, and up the internal wall and join it to the interior wall vcl?Well you have to connect the [under]floor VCL to the wall VCL so membrane is the obvious possibility. I suppose you might be able to use a multitude of tape, or perhaps some liquid-applied barrier but they are probably at least as awkward.]]> Installing Vapour control layer in timber frame garden room http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301364#Comment_301364 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17823&Focus=301364#Comment_301364 Wed, 26 Apr 2023 23:30:48 +0100 Viking House