Concreet floor

[ajeli]

In the process of refurbishing the kitchen I discovered damp problems with the floor which was made out of old clay tiles resting on soil.
To fix a problem I got a builder to come in and lay a concrete slab.

He did that a couple of days ago and he is coming back to lay foam insulation and screed. I'm not sure whether the concrete is of the right depth and what it should be the depth of the insulation foam and the screed.

At the edge of the wall the concrete laid is 2 inches deep and the builder claims that in the middle of the room is deeper closer to 3 inches and that, that should be sufficient for what I'm trying to do.

He also plans to put 3 inches worth of insulation and another 3 inches screed. Does the dimensions and the combination of materials sound ok?

Also, once the screed is laid, I'm planning to put laminate floor, the builder tells me I only need to wait 2-3 days before I put the laminate down. Reading other postings on this forum I get the impression I should be waiting longer than that. Any suggestions here?

cheers

 

[simoniris]

3 inches of concrete will be fine, bit of a bodge starting at 2" at the perimeter though [although if he's reinforced it, this 50mm/75mm/50mm slab is just about passable, just a real bodge! Why ever didn't he level it across the full width??!!.... could he not be bothered to dig it out properly?
Insulation should be roughly 75mm with a 25mm thick board cut to create an upstand to the perimeter of the screed, although if it's only one internal room in a uninsulated house it begs the question, 'why bother?'. The 75mm approximation is what would be used under an entire new slab. 75mm of screed is a bit heavy, 40mm would be adequate over a groundbearing slab & insulation.

 

[ajeli]

Thanks for your reply, is being very helpful.

I had to remove the soil, the builder didn't do it. It would have costed quite a bit for him to do that. He had a look at it once the soil was removed done but he never said anything about leveling it so we didn't do it.

My concerns are what can happen if the concrete slab is below the 3 inches depth. Any chance I'll get damp coming in later on? I'm putting a brand new kitchen on top and I don't want to risk money and have to do this job again in a couple of years time.

Also, can I lay the laminate floor a couple of days after the screed has dried off?

cheers

 

[simoniris]

Thickness of slab will not really have a bearing on whether damp comes through, you need to lay a membrane [1000 or 1200g polythene sheet from your builders merchant will do]
The correct construction for your slab would be [I don't know how large it is so treat these as approx thicknesses, could go thinner if slab small] 100mm type 1 stone, sand blinding, 1200g membrane, 75mm insulation, 100mm concrete, levelling screed [approx 3mm] floor covering.