Green Building Forum - Parge coat and floor joist question. Wed, 16 Sep 2026 17:29:53 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Parge coat and floor joist question. https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206413#Comment_206413 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206413#Comment_206413 Sat, 02 Aug 2014 13:19:13 +0100 woodgnome Sorted membrane for "Tony Tray".
Blockwork/ cavity construction.
Whats the best method of maintaining airtightness where the joist runs parallel with the wall?
Is it easiest to lay the first row of blocwork that runs parallel and parge before starting to fit joists..or try to parge when joist fitted..or put membrane around all perimiter and seal as at joist ends.
Next question. Whats preferred parge coat made up of? I was thinking either a bagged parge coat or just sand/ cement / lime at 6:1:1.
Last question.Do you parge internal partition blockwork walls as well as perimiter.
Internal walls sat on reinforced suspended slab.
Thanks]]> Parge coat and floor joist question. https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206414#Comment_206414 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206414#Comment_206414 Sat, 02 Aug 2014 13:32:15 +0100 tony
Tonytray too, crucial in my opinion.

Parge coat is anything sloppy and sticky, wet plastering is a lot better though.]]> Parge coat and floor joist question. https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206418#Comment_206418 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206418#Comment_206418 Sat, 02 Aug 2014 14:06:12 +0100 woodgnome I also tink it will be easier putting the tray all the way round the perimiter wall rather than trying to parge behind the joists next to a wall or run a course of blocks, waiting to dry then parging.
What about parging internal block partition walls..or is a plaster coat sufficiently airtight?
No plasterboard used on walls at all.]]> Parge coat and floor joist question. https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206419#Comment_206419 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12391&Focus=206419#Comment_206419 Sat, 02 Aug 2014 14:31:25 +0100 tony
No need to parge if you are wet plastering but it is crucial to seal the tonytray to the plaster with expanded metal to give a good key and hold it in place. Some plasterers do not plaster to the floor and they must fully catch the tray everywhere.]]>