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How to re-seal slate flooring?

Hello all, I was wondering if I might be able to get some advice, please?

We have slate tile flooring in our sunroom which is badly degraded. You can see in the photos whole portions of the surface are gone and others are cracked and flaking.

We can't afford to have this properly repaired at the moment so what I was aiming to do is clean the whole area thoroughly then try and somehow re-seal it.

Can anyone provide some advice on this please? I'm imagining just some kind of hard-wearing sealant applied with a roller?

Thanks very much

Paul

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MitchellMc

Hi @ptaylor,

From the photos, it looks like the slate has lost a significant amount of its thickness in the worst effected areas, to the point where the grout lines and tile edges are now higher than the remaining surface. In that condition, simply cleaning and rolling on a sealant is unfortunately not going to achieve much. Sealers made specifically for slate are really intended to protect intact stone, not to rebuild or stabilise a surface that is actively flaking and disintegrating. Even the better slate sealers are not especially hard-wearing and will tend to fail quickly when the substrate itself is breaking down.

At an absolute minimum, you would want to address the unevenness by chiselling or grinding back the perimeter edges and any high grout lines, so you have something closer to a flat, continuous surface. Without that, any coating or sealer will pool in the low spots, wear through immediately on the high spots, and look patchy very quickly. Even then, a sealer alone will not stop further degradation, it will only slightly slow it.

Given the state of the tiles and the need for a budget-conscious solution, it may be worth considering a cement-based self-leveller applied over the entire area once it is thoroughly cleaned and properly primed. This would encapsulate the failing slate, give you a flat and stable surface, and buy you time. When finances allow in the future, that surface would then be suitable for a floating floor, such as hybrid or vinyl planks without needing to rip everything up again. It is not a perfect fix, but it is a far more realistic interim solution than trying to seal slate that has already lost much of its structural integrity.

That being said, all the areas away from the window look to be in quite reasonable condition and likely just require re-sealing.

Please let me know if you have any questions.

Mitchell

ptaylor

Thanks Mitchell. Do you reckon I could get away with just using the leveller to "patch-up" the worst affected tiles and then seal it all in?

MitchellMc

Hi @ptaylor,

You could patch just the worst‑affected tiles with a self‑levelling compound, but keep in mind that those patched sections will dry to a solid grey cement colour. They will stand out very noticeably against the surrounding slate, even after sealing. The difference in texture will also remain obvious because slate has a natural cleft and variation, while the leveller sets completely smooth.

If your goal is purely a functional fix to stop the flaking and remove trip hazards, then spot‑patching is workable. If you’re hoping for a consistent visual finish, unfortunately patching will highlight the damaged areas even more.

A full skim over the entire area gives a much more uniform appearance and will be easier to seal and live with until you’re ready for a proper renovation. But if budget is the priority right now, patching the worst tiles will still stabilise the area and buy you some time.

Mitchell

ptaylor

Thanks for the advice Mitchell! You've given me a few things to think about.

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