Tiles lifting, concrete floor - Tile Advice

[nogginthenog]

My neighbour had an outhouse converted to a utility room with a new back entrance. The place was built in the 1940s and I suspect the concrete floor has no DPM. The people who converted it did a generally poor job (I’ve already done remedial work on the roof and guttering for them).

The issue now is with the ceramic floor tiles. Some have lifted in the heavy traffic area inside the back door. The others so far are staying put. I know that in theory one should redo it all, but ripping up the rest of the tiles isn’t an option, because there are units and appliances, and they wouldn’t want the disruption.

My question is what could I re-bed the tiles in, to give a reasonable chance of staying put? There isn’t any depth for a localised liquid DPM as well as tile adhesive. I was thinking of using a cement-based exterior adhesive onto the concrete (plus SBR?) and hoping for the best.

Cheers
Richard

 

[Tile Shop]

The liquid DPM will be microns thick, not millimetres, shouldn't be any height issues.

All cement based adhesives are suitable for internal and external use but without a DPM, the sulfates within the rising moisture will attack it long term unless you are laying a breathable tile (quarry tile or natural stone with breathable sealer)..... as you have found.

Liquid DPM's or vapour barriers like ditra, don't stop damp.... they kinda suppress and re-route it. So even with the DPM, the moisture will look for the quickest exit point and chances are you will get damp up through the walls or congregating beneath the other tiles or under units and around the DMP'd area. So installing it under a small section of a floor is going to gain you little and cause other possible problems elsewhere.

So unfortunately they may need the disruption to prep the floor properly before considering re-tiling with anything other than quarries or stone.

 

[nogginthenog]

Thanks