Grout Types Explained: Sanded, Unsanded, Epoxy, and More

Every grout question, from "why did my pen not stick" to "what should my contractor use in the shower", comes back to what the grout actually is. There are four families you will meet in a home.

Sanded cement grout

The workhorse for joints 3mm and wider, which means most floors. Fine sand gives it bulk and crack resistance, and its slightly gritty, matte surface is very porous, so it stains easily and drinks sealer. The good news for refreshers: that porosity means grout pens bond to it extremely well. If your floor grout looks like fine sandpaper up close, this is what you have.

Unsanded cement grout

Smooth cement paste for narrow wall joints under 3mm: subway tile, mosaics, polished stone (where sand would scratch). Slightly denser than sanded but still porous, and still a good grout pen candidate. Most bathroom wall grout is unsanded.

Epoxy grout

A resin and hardener system, no cement at all. It is nearly waterproof, barely stains, and is the premium choice for showers and kitchens, at two to three times the material cost and more demanding installation. Its glassy, non-porous surface is also why grout pens struggle on epoxy: there is nothing for water-based pigment to soak into. If water beads on your grout and stains wipe off with a cloth, suspect epoxy, and test any pen on a hidden spot before committing.

Urethane and hybrid grouts

Pre-mixed buckets that aim for epoxy-like stain resistance with easier installation. Like epoxy, their sealed surfaces take pigment poorly. They are also the reason "my new grout looks great" rarely leads to grout pen purchases: modern hybrids hold color well on their own.

Identifying what you have in 60 seconds

• Water drop test: a drop that soaks in and darkens the grout means cement (pen-friendly). A drop that beads means epoxy, urethane, or well-sealed cement.
• Texture: gritty = sanded cement. Smooth and chalky = unsanded cement. Smooth and slightly plasticky = epoxy or urethane.
• Age: pre-2000s homes are almost always cement grout unless renovated.

What this means for your refresh

Cement grout, sanded or unsanded, takes pen pigment well once it is clean and dry (see the prep guide). Sealed cement grout may need the seal to wear or be stripped in high spots for even color. Epoxy and urethane are wipe-test-first territory, and honestly, if epoxy grout looks bad, the problem is usually surface dirt, not the grout, so start with a deep clean. For full regrouting decisions, grout type is also a price lever: see the cost guide for the epoxy premium, and quiz a contractor on type using the hiring guide.