Tiling a floor onto old stone flags/bare earth.

Question

We have an old stone floor, with a few gaps between them, which I believe is laid straight onto the bare earth. I don't want the flags so need to cover it before tiling with large wood effect tiles. Do I put a damp proof membrane down first before a self levelling compound or would you advise putting something down to seal the floor before adding the membrane and SL compound.

Ervin · Accepted Answer

I suggest you level it with latex leveling compound and then you can put it on top. waterproofing

Darren · Answer

Moisture test the floor first but will more than likely need a dpm one coat two part solution (damp proof membrane) get a moisture tolerant self levelling compound and sandwich coat the membrane. Compound/dpm/compound. Alternatively uplift stone, sheet membrane, concrete/dpm/compound. Hope this helps.

Gustavo · Answer

If your old stone flags are laid directly onto bare earth, I would definitely recommend installing a proper damp proof membrane before any tiling. This will prevent rising damp and moisture from damaging the adhesive or tiles later on.

The best approach would be:
	1.	Clean and stabilise the surface, filling any large gaps between the stones.
	2.	Lay a DPM (damp proof membrane) sheet across the entire area.
	3.	Apply a self-levelling compound on top to create a flat, solid surface for tiling.
	4.	Once fully cured, you can proceed with tiling using a flexible adhesive suitable for underlayment with slight movement.

Avoid tiling directly onto the stone or bare earth — it won’t last long and can lead to cracking and damp issues.

— Gustavo | MG Elite Maintenance

Alaman · Answer

if the old stone flags are laid directly onto bare earth, it"s important to manage both moisture and stability before tiling.

Kamil · Answer

Hi there,

For an old stone floor laid directly onto earth, you need to create a stable, moisture-protected base before tiling, especially with large-format tiles. The general approach is:
	1.	Check moisture levels: Floors directly on earth can have rising damp, so a damp-proof membrane (DPM) is essential.
	2.	Prepare the surface: Remove any loose debris and fill large gaps between the flags with a sand/cement mix or floor leveling mortar. You want a reasonably flat surface for the DPM.
	3.	Lay a damp-proof membrane: Typically a 1200 gauge polythene sheet, lapped and taped at joins, and turned up the walls slightly. This prevents moisture coming through.
	4.	Screed or self-leveling compound: You can pour a self-levelling compound over the DPM, ensuring the floor is flat and ready for large tiles. Depending on the gaps and unevenness, a thin screed layer may be needed first.

Tip: Don’t apply the SL compound directly onto bare stone/earth—always have the DPM in place first. Some installers use a primer recommended by the SL compound manufacturer for better adhesion.

Adam · Answer

Maybe fill gaps with concrete and seal with resin , best to send me photos

Philip · Answer

I would lay waterproof rein then latex before laying floor

Simon · Answer

Hello, based on your description I would suggest filling the voids, screeding the floor with an epoxy membrane then laying your tiles. If the epoxy is too costly for you then you could use a standard water proofing such as thompsons.
Without seeing it is hard to give a definitive answer but that is my best opinion in the circumstance.
Kind regards
Simon

Tiling a floor onto old stone flags/bare earth.

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