Quarry Tiles: Seal Them or Not, and How to Clean Them

Quarry tiles are the plain, unglazed clay floor tiles you find in Victorian sculleries, Edwardian porches, church aisles and old pub kitchens. They are fired from natural clay rather than pressed from porcelain dust, so they are thick, hard and slightly absorbent, and they behave differently from the ceramic and porcelain tiles most people buy today. Across Bromley, Beckenham and Penge we lift, relay and restore them often, and the same handful of questions come up every time: should they be sealed, why do they turn white, and can a cracked one be matched?

This page answers those questions using the manufacturers’ own fixing and cleaning guidance, plus what we see on real floors around Bromley Tilers‘ patch of south east London.

What quarry tiles actually are

The name has nothing to do with stone quarries. A quarry tile is a fired clay tile, made in much the same way as a brick, and usually left unglazed so the colour runs right through the body. The traditional British colours are red, brown and blue-black, and old floors often mix them in a chequerboard or a border pattern.

Ketley, whose factory in Brierley Hill in the West Midlands has been making clay products for more than 200 years, makes its quarry tiles from Etruria Marl clay. Its laying guide says the fired tile is dense, hard wearing and resistant to acids, alkalis, oils, grease and fats, which is why quarry tiles were the standard floor for commercial kitchens for most of the last century. Ketley’s tiles are 18mm thick, which makes a quarry floor noticeably heavier than most modern tiled floors.

Slip resistance is the other reason they last in kitchens and porches. Ketley reports its quarry tiles test at R11 in shod conditions and Category C barefoot, the top barefoot rating. If you want to compare that with a porcelain tile you are considering, our page on tile slip ratings explains what R and PTV numbers mean.

Quarry tiles versus terracotta, encaustic and porcelain

Terracotta is also fired clay, but usually fired at a lower temperature, so it is softer and much more absorbent. It almost always needs sealing indoors. Quarry tiles are denser.
Encaustic and geometric tiles (the patterned Victorian hallway floors) have the pattern inlaid in different coloured clays. They are often mistaken for quarry tiles when worn, but they need gentler cleaning.
Porcelain “quarry effect” tiles are printed to look like clay. They are cheaper, lighter and need no sealing, but they lack the through-body colour, so chips show white or grey.

Do quarry tiles need sealing?

New quarry tiles generally do not. Ketley’s guide says plainly that sealers are not necessary but can be used indoors in certain situations. The fired clay is hard enough to shrug off normal foot traffic, and an unsealed floor keeps its matt, natural look.

Worn unglazed quarry tile floor between church pews — An old, unsealed quarry tile floor in a church aisle, worn but intact | Quarry Tile Floor by Bill Nicholls (CC BY-SA 2.0), via Wikimedia Commons, https://commons.wikimedia.org/wiki/File:Quarry_Tile_Floor_-_geograph.org.uk_-_5357487.jpg

Where a sealer earns its place is in a domestic kitchen where oil and food are dropped, a utility room, or a floor you want to be easier to mop. In that case use an impregnating sealer made for quarry tiles, which soaks into the clay without leaving a surface film, rather than a varnish-style coating that sits on top and wears patchily in walkways.

The old-floor exception: let it breathe

Old quarry floors are a different case. Many Victorian and Edwardian floors in Bromley’s older streets were laid straight onto a lime or sand bed over earth, with no damp proof membrane. Moisture from the ground rises into the tiles and evaporates from the surface, and the floor copes with that because nothing traps it.

Seal one of those floors with a film-forming coating, or lay a rubber-backed mat or vinyl over it, and the moisture has nowhere to go. It builds up under the coating, lifts it, and pushes salts out through the grout joints. If your floor has no membrane, either leave it unsealed or use a sealer whose maker states it is suitable for floors without a damp proof course, and check with the maker first. If the floor sits in a listed building or a conservation area, speak to the council before you change the floor build-up.

Why quarry tiles go white: efflorescence

A white powdery bloom on quarry tiles is almost always efflorescence: soluble salts carried up from the bed or screed by moisture and left on the surface as the water evaporates. On a new floor it usually appears in the first weeks while the screed and grout dry out. On an old floor it points to damp coming up from below.

What to do about it:

New floor: brush the dry salts off and wipe with clean water. Do not seal over it. It normally fades as the bed dries.
Old floor: brush and wipe the same way, but also look for the moisture source. A blocked air brick, a raised path outside, or a membrane laid over half the floor can all push damp into the tiles.
Do not keep scrubbing with strong detergents. Ketley warns that strong detergents can cause scumming on quarry tiles.

How to clean quarry tiles

Day to day, quarry tiles need very little. Ketley’s guidance is to sweep, then wash with warm water and a suitable non-soapy, neutral, sulphate-free detergent, and then rinse with clean water. Its most useful tip is easy to miss: always dampen the tiles with clean water before applying any cleaning product. A dry clay tile draws the cleaner into its body; a damp one keeps the treatment on the surface where it does its work.

For a newly laid floor with cement or grout residue, Ketley suggests a cement residue cleaner such as Lithofin KF Cement Residue Cleaner. These are acidic, so follow the safety instructions, keep them off neighbouring stone, and test a small patch first.

Restoring an old, grimy quarry floor

Find out what is on it. Many old floors carry layers of red polish, wax or old sealer. Water beading on the surface is a sign of a coating.
Strip coatings with a stripper made for them, working in small areas with a scrubbing pad, then rinse well.
Deep clean with a heavy-duty tile cleaner, again dampening the floor first.
Let it dry fully, which can take a week or more on an old floor in winter, and watch for efflorescence before deciding whether to seal.
Repoint failed joints before sealing, not after.

Laying quarry tiles: the numbers that matter

Quarry tiles are laid more like paving than like a thin porcelain floor. Ketley’s laying guide gives these figures:

Joint width: 6 to 10mm.
Bed thickness: about 6mm for cement-based adhesive, 15 to 25mm for a cement mortar bed, and up to 70mm for a semi-dry bed.
Screed timing: where a screed is used, the concrete base should be at least 4 weeks old and the screed left to mature for at least 2 weeks before fixing.
Grouting: wait 12 hours after laying before grouting, except on a semi-dry bed, where the tiles should be grouted within 4 hours.
Grout mix: a 1:1 cement to fine sand mix for joints under 6mm, and 1:3 for wider joints. Too wet a mix dries fast and cracks out of the joint.
Full bed, no voids: the tiles must sit on a rigid bed with nothing hollow underneath, so the load goes straight through to the base.

Ketley’s guide also says a suitable damp proof membrane should be built into new floors and that movement joints should be designed in. That is right for new work. It is the old floors without a membrane that need the breathing approach above.

The weight is worth planning for on a suspended timber floor. An 18mm clay tile on a mortar bed is heavy, and a bouncy joist floor will crack the joints. On timber we usually recommend a thinner tile and an adhesive bed over a properly fixed board, or a different tile altogether.

Replacing a cracked or missing quarry tile

Single tiles crack on old floors where the bed has hollowed out or something heavy has been dropped. Cutting out the broken one is the easy part, and our guide to replacing a broken tile covers the method. Matching it is harder.

Size: old British quarry tiles were not standardised and ran from roughly 6 to 12 inches square. Measure yours in millimetres and inches before you shop.
Thickness: old tiles are often thicker than new ones. A thinner replacement can be packed up on a deeper adhesive bed.
Colour: a new tile looks brighter than a hundred-year-old neighbour. Reclamation yards are often the best source, and a tile taken from under a kitchen unit or from inside a cupboard is a perfect match.

Frequently asked questions

Are quarry tiles slippery when wet?

Less than most tiles. Unglazed quarry tiles have a slightly textured clay surface, and Ketley reports its tiles at R11 shod and Category C barefoot. Grease, polish or a glossy sealer will make any floor slippery, so keep the surface clean and avoid shiny coatings.

Can you paint quarry tiles?

You can, with a floor paint made for tiles, but it wears in walkways and is hard to remove later. On an old floor without a membrane, paint traps moisture in the same way a film sealer does and tends to blister.

What colour grout goes with red quarry tiles?

Traditional floors used a plain cement and sand grout, which reads as mid grey. A warm grey or a sandy buff grout suits red tiles and hides dirt better than white.

Can you lay quarry tiles outside?

Ketley sells its tiles for external terraces as well as indoors, and says the bedding-to-base method suits external use. Outside, check the tile is frost resistant, build in a fall so water runs off, and allow for movement joints.

How do I get rid of the white marks on my quarry tiles?

White marks are usually efflorescence. Brush off the dry salt, wipe with clean water and let the floor dry. If the marks keep coming back on an old floor, look for a damp source rather than reaching for stronger cleaners.

Should I lift an old quarry tile floor to put in a damp proof membrane?

Only if there is a real damp problem the floor cannot manage, and only after checking whether building regulations or listed building rules apply. Many old floors work well as they are once coatings are removed and air bricks are cleared.

020 8058 5574

contact@bromleytilers.co.uk