Screed.... minimum thickness

[mark b]

I've got a floor to screed. Concrete pad already done.

Room height could be a problem so I need the screed as thin as I can get away with. Any ideas welcome.

Thanks

mark b

[Rick Dipper]

My research suggests 65mm, I have the same issue you do. However I have been looking for screed over UFH, so without the UFH you might get a bit less.

Rick

[asher]

On my kitchen and bathroom floors I used an "epoxy screed" over an existing concrete floor [1]. This is a standard sand/cement mix made with an epoxy/water mix (from memory I think it was "Superbond SBR") instead of plain water. The thickness of the screed on my floor varies from about 0.5" to 1" (depending on the concrete underneath) and shows no signs of cracking after 8 years (except where we dropped the cast iron bath on it while moving it back into the bathroom, but then it did take 5 of us to shift it).

I'm not sure how long you ought to leave a freshly made concrete pad to dry out since the screed is waterproof. Best to check with the epoxy manufacturers.

Be aware that it is extremely quick setting (30 mins or so) and a bit of a bugger to work with. Also, do *not* let it set in your cement mixer, not even the thin layer left after pouring...

Asher.

[1] To satisfy the mortgage company who believed the laughable survey about damp (epoxy screed is also waterproof). Quite how the "rising damp" that they diagnosed could have produced puddles on the floor I'm not sure. Fixing a dodgy airbrick with no rain cap above the window before doing the floor fixed all the damp problems.

[mark b]

I think 65mm is the norm but I was hoping to get away with 40mm or so and that someone would verify this rather than me finding out the hard as concrete way that its not ok. I'd have thought a good dollop of pva in the mix would help but I'm only guessing.

cheers

mark b

[mark b]

Thanks Asher. I shall investigate the SBR. The 30min set seems a bit scary!

mark b