Laying carpet on quarry tiles 9 February at 10:20PM in In my home (includes DIY) MoneySaving 2 replies 111 views

BrendanMG

I'm after some advice from you knowledgeable folks.

I'm doing a refurb of an early 1900s terraced house, which has quarry tiles laid on ash in the dining room and kitchen. On reflection, I should have dug the tiles up and laid a concrete slab with a damp proof membrane. This didn't happen unfortunately. I was guided by someone that turned out to be a cowboy builder in the true sense of the phrase, and he assured me that a liquid damp proof treatment over the tiles has been adequate to prevent any dampness coming through on previous homes he has worked on. I didn't know at that time if dampness was indeed rising through the floor as I had only purchased the house a couple of months previous. The tiles were wet when I lifted the laminate floor and fibreboard that was underneath, but that may have been due to sweating. The floor quickly dried out in the days that followed, and there were no signs of dampness over the summer months while the tiles were exposed and the rest of the refurb was progressing.

The builder did pour on a liquid damp proof membrane, followed by a self-levelling screed, the latter being extremely badly applied (it was essentially tipped onto the floor and allowed run to the lowest point, where it congealed - no floating into the corners etc).

The builder has long since been fired, and the refurb is nearing completion, but, worryingly, some spots of moisture are now starting to appear on the floor of the dining room. I don't know whether it's dampness or the tiles sweating because the liquid DPM is preventing them from breathing. I don't know what to do. There's no money left in the budget to dig the floor up and lay a concrete slab, and I'm worried about laying underlay and carpet on the floor as it is, for fear that both will get damp and mould will follow. I'm considering scraping off the self-levelling screed and applying KA Tanking Slurry, before laying the underlay and carpet. That might work if the moisture I'm seeing is dampness rising from the dirt underneath the tiles, but it would be ineffective and might even worsen the problem if the moisture is due to the tiles sweating.

The carpet fitter's opinion is that the tiles should be able to breathe with underlay and carpet laid on top, but he wasn't sure if the liquid DPM that was poured might prevent them from doing so.

All thoughts and opinions are welcome. I've learnt a lot from this refurb and now realise that floor should have been dug up, but it's not an option at this stage. How best to proceed is the question.

Many thanks in advance. 

grumbler

Do I understand correctly that the 'liquid DPM' and then the screed were  laid on the tiles?

If so, I don't understand this talk about breathing and sweating. How long ago was the screed done? If it had enough time to dry (did it?), but the 'liquid DPM' is failing to do its job and there is constant supply of water to the ground under the floor, you really don't want all this moisture to get to your house via 'breathing'.

And how tanking slurry is better than a normal plastic membrane laid on the screed under the underlay? If the area is wider than 4 m, lay it with big overlap and tape the joints.

FreeBear

BrendanMG said: I'm doing a refurb of an early 1900s terraced house, which has quarry tiles laid on ash in the dining room and kitchen. On reflection, I should have dug the tiles up and laid a concrete slab with a damp proof membrane.

The builder did pour on a liquid damp proof membrane, followed by a self-levelling screed, the latter being extremely badly applied (it was essentially tipped onto the floor and allowed run to the lowest point, where it congealed - no floating into the corners etc).

The carpet fitter's opinion is that the tiles should be able to breathe with underlay and carpet laid on top, but he wasn't sure if the liquid DPM that was poured might prevent them from doing so.

Out of the three, the carpet fitter is right.

If you had dug out the (original ?) quarry tiles and replaced with a slab of concrete, you would have ended up pushing the damp in to the walls.

Tipping a can of liquid DPM over the tiles and then sealing it with a screed is just as bad. But at least there is a chance that the quarry tiles can be rescued - Quite likely some will get damaged when removing the screed & liquid DPM...

A felt underlay with a hessian backed carpet would have been fine without any "remedies" applied to the quarry tiles. Hopefully, you haven't gone for an injected chemical DPC and slapping waterproof render/plaster on the walls. If you have, that is only going to store up problems 5 or 10 years down the line.