New flooring. DPC?

[BlairB7]

Good afternoon,

Looking for a bit of advice,

Going to screed a downstairs concrete bathroom floor prior to fitting with tiles, doesnt look to be any DPM down previously. So basically on top of the concrete floor, prior to screeding, I was going to put either a 'one coat' paste like one (potentially Ardex DPM 1C or similar), or a plastic membrance like one (capital valley plastics damp proof membrane or simlar).

If using the Ardex would this need to be primed prior to adding the screed (Mapei Ultraplan 3240 self levelling compound) and can i just put this down right on top of the Ardex?

If using the membrane would the screed actually take to this or would some sort of underlay etc be required?

Thanks

 

[tomfe]

How thick is your screed?

 

[BlairB7]

I was only going to get a 25kg bag which says it gives 3mm thick for 6m2 floor area. Can always get another bag(s) if necessary. Would this be needed?

Had been mentioned to me before that I should use a primer hence the reason I ask.

Thanks

 

[Notch7]

I was only going to get a 25kg bag which says it gives 3mm thick for 6m2 floor area. Can always get another bag(s) if necessary. Would this be needed?

Had been mentioned to me before that I should use a primer hence the reason I ask.

Thanks

Do you mean you are laying self level compound, rather than screed?

What you referring to as a concrete bathroom floor, probably is screed.

Are you sure the floor has no dpm? - is the house very old?

Basically you cant put self level over plastic dpm and Im not sure you can put it a liquid dpm either.

 

[BlairB7]

Apologies, yes what I am meaning is self level compound.

The house is around 100 years old but has had a ground floor extension (not sure when this was built though), being the bathroom. What was originally down was vinyl flooring. I removed this to find rotted plywood under that and then, what I thought was, concrete. The rotted plywood seems to have came from a leak (ie not rising damp, which I originally feared).

I can’t be sure if any DPM is present, hence why I was going to put this liquid DPM down. It’s purely as a precaution I thought to put any down as there doesn’t seem to be any damp anywhere.

Can’t you use a primer over the liquid DPM prior to screed/compound?

Thanks for your reply,
Blair