Knowing how to grout shower tile correctly is the difference between a wall that stays sealed for a decade and one that grows mildew and crumbles within a year. The tile gets the attention, but the grout is what keeps water from creeping behind your walls. Done right, this is a weekend project that saves the $400 to $800 a pro would charge to regrout a standard shower.
This guide walks through grout selection, mixing, application, and the critical sealing and curing steps most beginners rush.
Choosing the Right Grout
Grout choice matters more in a shower than almost anywhere else because of constant moisture. You have three practical options:
- Sanded cement grout — best for joints wider than 1/8 inch. Strong and economical, but porous, so it must be sealed.
- Unsanded cement grout — for joints 1/8 inch and narrower, like polished tile and glass. Also requires sealing.
- Epoxy grout — waterproof, stain-proof, and never needs sealing. Costs more and sets fast, but it is the top choice for shower floors and high-moisture zones.
For most shower walls, a quality sanded grout is fine. For the shower pan and any area that stays wet, epoxy is worth the extra effort and roughly $50 to $90 per unit.
Tools and Materials You’ll Need
Gather everything before you start, because grout begins setting the moment it is mixed. You will need a rubber grout float, two large sponges, a bucket of clean water, a margin trowel, a grout haze remover, painter’s tape, rubber gloves, and a grout sealer if you chose a cement-based product. A drill with a mixing paddle speeds up batching but is optional for small showers.
Step 1: Prep the Surface
Confirm the thinset under your tile has cured for at least 24 to 48 hours. Scrape out any thinset that squeezed up into the grout joints — joints should be at least two-thirds deep for the grout to bond properly. Vacuum the lines, then wipe the tile face clean. Tape off any edges where the tile meets a tub, fixture, or different surface so you keep clean lines.
Step 2: Mix the Grout
Add powder to water gradually, not the reverse, following the ratio on the bag. Mix to a peanut-butter consistency that holds a peak without slumping. Let it slake — rest undisturbed — for 5 to 10 minutes, then remix briefly. Never add more water after slaking, as that weakens the grout. Only mix what you can use in about 30 minutes, since cement grout stiffens quickly.
Step 3: Apply the Grout
Scoop grout onto the float and spread it diagonally across the tile at a 45-degree angle. Working diagonally forces grout into the joints and prevents the float edge from digging it back out. Press firmly and make several passes over each area to pack the lines completely. Work in sections of about 3 to 4 square feet so the grout does not harden before you can clean it.
Step 4: Clean the Tile Face
Wait roughly 15 to 20 minutes until the grout firms up but is not rock hard. Wring a damp sponge nearly dry and wipe diagonally across the tile in light strokes, rinsing the sponge often. Avoid dragging straight along the joints, which scoops grout out and leaves uneven lines. Do not over-wet — excess water washes pigment out and creates weak, blotchy joints. Shape the lines so they are smooth and consistent.
Step 5: Remove the Haze
A thin cloudy film, called grout haze, appears as the surface dries. After a couple of hours, buff it off with a dry microfiber cloth. If a stubborn haze remains the next day, a grout haze remover handles it. Skip this step and your gleaming new tile will look permanently dull.
Step 6: Cure and Seal
Let cement grout cure undisturbed for the time on the package, usually 48 to 72 hours, before exposing it to water. Do not shower during this window. Once cured, apply a penetrating grout sealer with a small applicator bottle or brush, wipe off the excess, and let it dry. Reseal cement grout once a year to keep it water-resistant. Epoxy grout skips sealing entirely.
How Much Grout to Buy
Running out of grout halfway through a wall is a common rookie mistake, and a fresh batch rarely matches the color of the first exactly. Estimate your needs before you start. Grout coverage depends on tile size, joint width, and joint depth — larger tiles with narrow joints use far less grout than small mosaics with wide lines. Most bags list a coverage chart for common tile sizes; use it, then buy at least one extra unit so you can finish the job and keep a little for touch-ups. Mixing all your grout from the same lot number also keeps the color consistent across the whole shower.
Fixing Common Grout Problems
Even careful work can hit snags, and most are fixable. Pinholes and low spots in the joints usually mean the grout was too wet or wiped too aggressively — pack a little fresh grout into the gaps while the surrounding lines are still workable. Cracking along a joint typically signals movement, which means that line should have been caulked, not grouted. Discoloration and blotchy lines often come from too much water during cleanup washing pigment out unevenly. If a section looks bad, it is better to rake it out and redo it than to live with it, since grout is the part of the shower you will stare at every day.
Pro Tips for a Lasting Finish
Caulk, not grout, belongs in the corners and where the wall meets the tub or pan. These joints flex with the building and seasonal movement, and rigid grout will crack there every time. Use a mildew-resistant silicone caulk color-matched to your grout. Keep the bathroom ventilated for the first week so the grout cures evenly, and your finished shower will stay sealed and clean for years.
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