How thin can floor screed be?

[woodman-46]

Hi,

I have an "add on to my workshop" that has a floor made from slabs that have been mortared. These seem very solid as a floor but, although level are a little uneven to each other in places. I would like to level it off but only have about 2-3cm clearance under a double glazed door that swings over the floor. I can't raise the door and so is there a screed or other that can be laid to under that depth? Also I would like to put a DPM under the screed or make sure the end result is waterproof. Is it best to make up some sort of waterproof mix or is there something on the market that I can use that would give a smooth level surface and is waterproof and have strength at that depth? If possible I would rather avoid having to lay down membrane.

Thanks in advance

James

 

[brumylad]

I have seen articles on the net for acrylic floor screeds that can be layed in a thickness of as little as 3mm.