Boarding floor on damp concrete

[camerart]

Hi,
I've just had some concreting done, and they're going to lay 18mm board on top of it tomorrow, so Friday to Monday.

I think the concrete will still be damp, so is it normal to lay board on damp concrete or should it be left to dry out first?
C

 

[^woody^]

It's normal and will be OK to lay temporary protection once the concrete has set

 

[camerart]

It's normal and will be OK to lay temporary protection once the concrete has set

Hi W,
I'm not sure what you mean by 'tempory protection' these boards are permanent, and will match the level in the adjoining room.
C

 

[JohnD]

You mean floorboards?

What will be between them and the wet concrete?

 

[camerart]

You mean floorboards?

What will be between them and the wet concrete?

Hi J,
18mm floorboards in the adjoining room and in the damp concrete section OSB board stuck down with adhesive,
to match height.
C

 

[23vc]

Massive no no surely. 1mm per day drying before covering normally

 

[camerart]

Massive no no surely. 1mm per day drying before covering normally

Hi 2,
I think it's 100mm thick, so do you mean 100 days?
C

 

[23vc]

That’s what I’ve always gone with. I know there’s the odd exception like some types of tile adhesive that can go on green screed, but I wasn’t aware that covering it with OSB was ok.

 

[^woody^]

Oh, I thought you must be referring to temporary board like ply or something to allow the builders to work on the floor. I could not imagine that you meant the actual finished flooring because that would be just mad. That slab needs to dry - a good few weeks unless some driers are being brought in.

 

[Notch7]

Hi,
I've just had some concreting done, and they're going to lay 18mm board on top of it tomorrow, so Friday to Monday.

I think the concrete will still be damp, so is it normal to lay board on damp concrete or should it be left to dry out first?
C

Do you mean concrete or screed?

I doubt concrete is flat enough for floorboards


There are some screeds like Mapei top em which can be tiled over within a day or so

normal drying rate is 1mm per day at least.

 

[JohnD]

Wooden flooring over a damp surface is usually given a moisture-proof barrier of plastic in between

 

[camerart]

That’s what I’ve always gone with. I know there’s the odd exception like some types of tile adhesive that can go on green screed, but I wasn’t aware that covering it with OSB was ok.

Hi 2,
Ok, I'll get them to lay it, so it all fits, but not stick it down, then I'll leave it to dry a bit and do it myself.
Thanks.
C

 

[Notch7]

Hi 2,
Ok, I'll get them to lay it, so it all fits, but not stick it down, then I'll leave it to dry a bit and do it myself.
Thanks.
C

The moisture will sweat under the plastic and migrate towards the edges

be careful at the walls, make sure plastering doesn’t go to floor and don’t put down skirting

 

[dazlight]

Why are they doing that ?
its best leaving it 28 days then a apply a moisture suppressant like uzin Pe404 , Mapei 1K turbo etc

 

[camerart]

Hi All,
As #12, I'll get them to fit the boards, then I'll lift them while it dries, before sticking them down later.
I will look into a barrier, or perhaps the adhesive will seal it.
It's screed with membrane under, on top of insulation on top of concrete with membrane under, on top of type 1, all wacked down.
Thanks, I'm glad I asked.
C.