Quarry tile on earth flooring

[dunstan]

Hi all,
I am struggling to figure out what to do with the flooring in our kitchen-diner renovation.
I have just discovered the original kitchen floor is quarry tiles laid directly onto earth.
Our original intention was to have LVT throughout both the kitchen and dining room, with a levelling screed on the kitchen floor butting up to ply or OSB on the suspended wooden dining room floor.
However, I understand this may not be a good idea on the basis that a liquid DPM and levelling screed would not be breathable, and could result in damp issues in the walls?
The quarry tiles are a little damp, as they were under decades old lino.
However, the tiled floor in the lean-to directly adjacent to the kitchen (which hasn't been covered up with lino) isn't damp.
See the small area of tiles through the open door.
Other point of context, the house is at the top of a hill, so we don't expect water table to be an issue.

Since I don't think the ground is likely to be excessively damp, might the risk of laying a non-permeable layer on top of it be acceptable?

I understand that best practice as far as modern standards are would be to lift the tiles, excavate down, lay sand, DPM sheets, insulation and then pour a screed.
What I don't understand, is how doing that would be any different in terms of the potential for damp getting into the walls, compared to sealing the tiles with a liquid DPM like SBT+ and then using a self levelling screed?
Both would trap moisture under the floor.

I am also considering the other option would be to retain the tiles if I can persaude my partner to accept the aesthetic, and manage to replace some damaged tiles that are laid verrrrrrrryyy tightly...

 

[mh12]

Hi Dunstan.
Welcome to the forum.
I've not researched much about Quarry tiles and what lays beneath them but here is my novice 2 pence approach.

Q: What are yout trying achieve? Insulation or just a breathable floor?

If its insulation then I would do the following did approx 250mm from the kitchen and then lay the following composition:
Geo membrane followed by 150 mm RPG followed by Geo membrane followed by 70 to 100mm NHL 5 slab but the depth of slab needs to be determined by your finished floor thicknes i.e. tiles. Dont think you can use LVT with this approach , wooden and might become potentially wet as no DPM (DPM is a NO NO with this approach).

If its just a breathable floor then I would dig out 100mm and lay geomembrane followed by 100 mm NHL 5 slab. Please make sure the product onto of the NHL slab is moisture resistant so you would potentially need to tile the floor with non stain tiles.

Much more experienced members will provide better input but thats what I would do.

All the best.

 

[Cubist]

Since I don't think the ground is likely to be excessively damp, might the risk of laying a non-permeable layer on top of it be acceptable?

Not really. A non permeable material would induce the same problem you saw with the Lino. Moisture would become trapped beneath it and then migrate into the nearby walls.

What I don't understand, is how doing that would be any different in terms of the potential for damp getting into the walls, compared to sealing the tiles with a liquid DPM like SBT+ and then using a self levelling screed?

Same result. Sealing the tiles and applying a liquid DPM would produce exactly the same result as above.

Right now that floor is breathing properly as it should and moisture rising through the tiles is evaporating into the rooms atmosphere just as it no doubt is in the adjacent room. Frankly, given that the tiles seem to be complete and undamaged, I would strongly recommend that you simply clean them up, apply a little linseed oil to their surface to brighten them a little and sort out the transition to the dining area floorboards.

 

[Flyfisher]

Feel the skin on your hand . . . my bet is that's completely dry.
Put on a rubber glove . . . wait 15 minutes . . . take off the glove and feel the skin on your hand. My bet is that it's all sweaty.

We have a small area of clay pamments on soil underneath an open staircase. They look and feel completely dry and cause no damp problems at all.
I recently moved a couple of cardboard boxes that had been stood on the tiles for the past year or so and the bottom of the boxes were damp and disintegrating because they had trapped what little moisture was breathing through the tiles.

 

[mh12]

Feel the skin on your hand . . . my bet is that's completely dry.
Put on a rubber glove . . . wait 15 minutes . . . take off the glove and feel the skin on your hand. My bet is that it's all sweaty.

We have a small area of clay pamments on soil underneath an open staircase. They look and feel completely dry and cause no damp problems at all.
I recently moved a couple of cardboard boxes that had been stood on the tiles for the past year or so and the bottom of the boxes were damp and disintegrating because they had trapped what little moisture was breathing through the tiles.

The penny droppeth. I've just realised moisture on the tiles is not such a bad things, means ground is breathing and behaving. It's not necessarily indicative of damp as such?

Just a thought, if this area of house was warmed up frequently will the floor dry up?

 

[a twig]

Warmer air can hold more moisture so yes it would be more likely that the water would be absorbed into the air, then with adequate ventilation can be circulated / removed

 

[a twig]

Also works the other way, if the tiles are cold and the air is warm and carrying moisture then that moisture will cool and condense on the cold tiles - again the more stagnant the air, the more likely this will happen.

 

[Westholme]

Please don't get rid of your quarry tiles. I uncovered quarry tiles that were covered with laminate flooring for years. The tiles were covered in white salt because the floor couldn't breathe. I cleaned the tiles using a plastic scrubbing brush and warm soapy water, then sponged them with clean water. I had to do this multiple times but it did the trick. Don't use anything abrasive as that will destroy the glazed finish.

You should be able to buy period quarry tiles from a local reclamation yard to fill the gap where the wall has been removed. You'll need to remove at least one brick course first. Your floorboards look good - the gaps seem very small such as you'd find in the best room in the house.

Personally I wouldn't put linseed oil on the tiles or any other sealant. Just use a mop or a scrubbing brush when they need a clean.

 

[mardinor]

I second Westholme's response. We also uncovered a quarry tiled floor under lino, in worse condition, 25 years ago. Laid straight to earth with no DPM. After a scrub, any residual salts/staining wear off with normal foot traffic. No need to seal. The floor breathes but is totally dry to touch. Remarkably. it is wonderfully cool in summer and yet not chilly in winter. We added an extension and laid reclaimed tiles to match that are indistinguishable (just buy ones the right size with mortar already removed, and butt tight).

And if you do choose LVT, surely teh breathability of anything underneath is irrelevant as the covering is vinyl plastic?

 

[Kearn]

Don’t seal them. Don’t cover them up with a screed and destroy them. Don’t hide them away to sweat. Don’t try to lift them and out other stuff underneath as they’ll break and you’ll never get them laid back the same and the wear marks showing centuries of traffic will go.

Vacuum and mop them occasionally, the natural patina from feet and paws does wonders.

That is a beautiful, old, and fairly intact floor. Many dream to find that under crappy Lino and modern coverings, few do.