Epoxy Grout vs Cement Grout: Which Is Right for Your Bathroom or Wet Room?

Epoxy grout, such as Mapei Kerapoxy, is a waterproof, stain-proof resin that outlasts cement grout in showers, wet rooms and hard-used floors, but it costs more and is harder to fit. Cement grout is easier to work, more forgiving and perfectly good on most walls and low-splash areas. Neither is simply better. The right choice depends on how wet and how hard-worked the surface is, so here is how I decide it job by job.

Key takeaways

• Epoxy grout is effectively waterproof and stain-proof. Cement grout absorbs water and can discolour.
• The grout does not waterproof the room. Correct tanking behind the tiles does that.
• Epoxy earns its place on shower and wet room floors, constant-use showers, and pale or coloured joints.
• Cement grout is the sensible default on most walls and splashbacks.
• Epoxy costs materially more, mostly because it is slower and more skilled to fit.

A dark marble wet room where the joints take constant water. On floors and showers like this, a waterproof epoxy grout keeps the lines clean for years. Wet room service

What is the actual difference between epoxy and cement grout?

Cement grout is a sand and cement based powder you mix with water or a latex additive. It is what most tiling is grouted with, and for good reason: it is cheap, forgiving to work, and easy to shape into a clean joint. Its weakness is that it is porous. Left unsealed it absorbs water, holds dirt, and over time it darkens, and in wet corners it grows the black mould everyone recognises.

Epoxy grout is a different animal. It is a two or three-part resin, hardener and colour-loaded filler that cures by chemical reaction rather than drying out. Once set it is effectively waterproof, resists staining from soap, wine, coffee and cleaning chemicals, and keeps its colour. Mapei Kerapoxy is the one I reach for most often. The trade-off is that it goes off fast in the bucket, so it has to be mixed little and often, worked quickly, and washed off the tile face before it cures, or it dries on the surface like a glaze.

Does the grout make the room waterproof?

No, and this is the single most important thing to understand before you spend more on epoxy. Grout is not a waterproofing layer. Water gets through and around grout joints in any wet area, which is why a shower or wet room has to be tanked behind the tiles with a system like Mapei Mapelastic or BAL Tank-it. The tanking is what keeps water out of the wall and floor structure. I explain the whole process in what is tanking.

So epoxy grout does not replace tanking, and it never rescues a room that was not tanked. What it does is stop the joints themselves absorbing water and discolouring. That is a durability and appearance upgrade sitting on top of the real waterproofing, not a substitute for it.

When is epoxy grout worth it?

Epoxy earns its extra cost in specific places:

• Shower and wet room floors. This is the wettest, most walked-on grout in the house. Epoxy here stays clean and does not soak up shower water.
• Constant-use showers. A main family shower running every day is exactly where cement grout tires first.
• Pale or coloured grout. A white or light grey joint in cement will grey off and stain. In epoxy it holds its colour. If you have chosen a specific grout shade to set off the tile, epoxy protects that choice. I cover picking the shade in the grout colour guide.
• Kitchen floors and workticked surfaces. Grease, food and heavy footfall punish grout, and epoxy shrugs it off.
• Steam rooms and pools. Any surface in near-permanent moisture.

If you are tiling a full wet room floor in dark marble or a busy shower, I will usually recommend epoxy for the joints and explain why. You can see the kind of wet room work it suits on the marble and natural stone page.

When is cement grout the right call?

Most of the time, on most surfaces, cement grout is the correct and sensible choice. It is right for:

• General bathroom walls above splash height.
• Kitchen splashbacks and low-water zones.
• Hallways, living areas and other dry floors.
• Any surface where you would rather put budget into better tiles or proper prep than into premium joints.

A well-mixed CG2 grade cement grout (the improved cementitious grout class), kept sealed where needed, gives a clean, long-lasting joint on the great majority of domestic tiling. Paying for epoxy on a dry feature wall is spending money where it does not do much. The skill is in matching the grout to the demand on it, not defaulting to the most expensive option everywhere.

Does epoxy cost a lot more, and why?

Yes, epoxy grout runs materially more than cement, and it is worth understanding where that extra goes so you can judge a quote. Industry framing is consistent on this: the resin material itself is several times the price of a bag of cement grout per unit, and it takes longer to fit. Because epoxy cures fast, a tiler works it in small batches, cleans each section off the tile before it sets, and cannot rush the tile-face cleaning without leaving a permanent haze. That is more labour and more care per square metre.

I do not price grout as a line item over the phone, because no two rooms are the same and the honest figure comes from seeing the job. What I will always do is tell you where epoxy genuinely pays off in your room and where cement is the better use of your money, then put the whole thing in a written quote. If you would like that assessment, get in touch and I will look at the room. If your existing joints have already failed, that is a regrouting job rather than a patch, covered on the regrouting and grout renewal page.

Switching an existing bathroom to epoxy

If you have a tired cement-grouted bathroom in Bromley and want the cleaner, longer-lasting finish of epoxy, the old grout has to be raked out to depth first, the joints cleaned and dried, and the epoxy fitted fresh. You cannot skim epoxy over existing grout and expect it to hold. Done properly it transforms how a shower ages, and it is one of the more worthwhile upgrades on an otherwise sound bathroom.

See: grout colour guide | what is tanking | how to spot good tiling