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Carpets, Lino & Flooring

Moisture control when laying flooring on top of quarry tiles

Anonymous user 09/03/2024 - 2.50 PM

We have quarry tiles in our late 1940's ex-council house kitchen and we found that the damp had come through and damaged the skirting board as well as the flooring that had been put down on top. We want to lay vinyl click flooring down but are worried about how to address the moisture that is trying to come through the tiles (there's a lot of efflorescense since removing the flooring)

Are you a tradesperson and able to answer this question?

1 Answer

Anonymous user

Without seeing the rh% of moisture in the sub-floor it's impossible to give 100% correct information, but as long as the rh% is under 97% you could prime the floor, use a latex based screed to give a smooth surface, use a surface DPM (as far as i'm aware only Ardex DPM 1 C is guaranteed over a sub-floor without a working mechanical dpm) then finally screed over the top again to protect it. If the readings are higher you will most likely need to dig out and replace the sub-floor with a new concrete base meeting building regulations, allow a minimum of 4 weeks from installation prior to taking any moisture readings and plan accordingly it takes on average 1mm per day for a concrete base to dry down to 75% rh which is the maximum moisture content for any flooring except real woods (65%), this means you will still need to use a surface dpm if you wish to fast track your flooring installation.

Answered6 July 2017