On 28 May, 21:35, Tim Watts wrote:
On 28/05/10 21:21, andrew wrote:



Tim Watts wrote:

I have toscreeda concrete floor slab.Screedis going over concrete,
not over insulation.Screeddepth was supposed to be 60 to 70mm, but
the slab ended up a bit thicker than intended, so in some areas, the
screedwill be down to about 40mm thick.
Will a normal dry mix sharp sand / cement be OK at that thickness, or
should I add anything (likeSBRetc.) Floor will be tiled.
I was going to use sand / cement in case I need to slightly slope
levels to match floors in two adjoining rooms.
Or should I consider any other type ofscreed?
Cheers,
Simon.

I would have though 40mm was OK, but it's getting near the limit.

With or withoutscreedfibres?

Can't answer that for dryscreed. However, I've done down to 15mmSBRscreedwithout fibres with no problems, on small areas (1m x 2m) and
25mmSBRscreedover 3x3m areas. I think theSBRbonding is too great to
allow easy cracking.

I've recently had 65^2 of uneven concrete screeded and I know it must be
thin in places as I had 1m^3 left over. even where it tapers of by a door
it hasn't given a problem yet though I fully expect to have to make good
with some epoxy.One chap and a laser level laid the lot in a day without
expansion joints which surprised me a bit.


Whats the process and quantities to mix SBR screed then? I have a
belle mixer that needs a good clean out !
Simon.