Dry structural screed?

soldsold · 19-06-2010 01:39AM #1

My beam and block floor where my extension meets the old part of the house is over a rockwool insulated, plasterboarded room, and if I pour a wet screed over the beam and block floor Ill have a real mess coming through the roof.

Is there such a thing as a dry structural screed? Even semi-dry?

Cheers,

S

FesterBeatty · 19-06-2010 09:57AM

No such thing as a dry screed. Its just concrete, and concrete comprises sand, cement, aggregate and water - without the water its just a pile of dust...

You can however simply fill the underside of the joints with expanded foam to prevent the screed from seeping through. Alternatively use precast wideslab or hollowcore. Generally speaking beam and block should not be used for anything other than a suspended ground floor. Anything above that and the H&S issues associated with its construction are significant (i.e walking on narrow beams while you place blocks, the possibility of slipping through, dropping a block if a beam shifts to one side...etc)

martin46585 · 19-06-2010 03:37PM

placing a regular screed will be no trouble as it will only be wet enought o hold it together when squeezed in a ball, though this would have no structural gain.
in the case of easyscreeds and the likes they use a polythene dpm sheeting so as not to float the insulation, this may do your job though not if you are after a bonded screed.
a friend of mine pumped the upstairs floors with 25n concrete xtra sand so as to surround the ufh pipes, his ceilings and walls were also finished down stairs, laid over dpm which was turned up the walls, not a single mark showed through.

soldsold · 20-06-2010 02:41PM

I need a bonded structural screed to give the beam and block floor it's full strength, I guess I can always replace the plasterboard and insulation if it gets messy. I had sealed the joints in the beams and blocks with expanding foam already so it looks like this is as much as I can do

Dry structural screed?

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