Level Concrete Floor with Sand

[benben5555]

Hi,

I need to level an uneven concrete floor before installing insulation and screed. I've seen that some people suggest using sharp sand to fill the hollows. does this sound reasonable? I think it would work as all it needs to do is allow the insulation to sit level?

I cant use letex or levelling compound as the area is too big and it would cost a fortune

 

[^woody^]

No it's a stupid idea.

 

[endecotp]

Is this "sand blinding", which I've seen suggested in Kingspan documents for solid floors, i.e. "sand blinding", polythene, insulation boards, screed.
Or is that something else?

I'm considering doing something similar, but I don't know how uneven my base is yet.

 

[noseall]

No it's a stupid idea.

Why? We use a soft building sand when blinding floors.

The surface of the slab should be smooth, flat and free from projections. Beam and block floors should be level and grouted. Rough cast slabs should be levelled using a thin sand blinding to ensure boards are continuously supported.

 

[^woody^]

Because the sand does shift. There are the practicalities of placing and keeping the sand in one place and compacting it in deeper troughs or wider areas.

All of this is overcome with a bit of cement and water and a few minutes of time.