Tiling around a bathtub requires cement backer board, a waterproofing membrane, and a 1/4-inch gap above the tub rim to prevent water damage.
Tiling a tub surround is a messy, multi-day project, but the finished result transforms a bathroom. The order matters more than the speed: substrate, waterproofing, layout, tile, grout, then caulk. Skip a step and moisture finds the gap. This guide walks through the full sequence for a standard alcove tub with a showerhead, the most common setup in U.S. homes today.
Why Regular Sheetrock Fails Around A Tub
Ordinary drywall soaks up moisture and swells, which destroys tile adhesion and breeds mold. The same goes for greenboard, which resists moisture but is not rated for constant wet exposure in a tub surround.
Instead, remove the old sheetrock down to the studs and install cement backer board. It holds up to wet conditions and gives thinset a textured surface to grab. This Old House’s tub surround guide recommends cement board rather than greenboard in a tub assembly. The board’s bottom edge must sit about 1/4 inch above the tub rim; that gap stops moisture from wicking up into the wall through capillary action.
Tape every seam with fiberglass mesh embedded in thinset, then roll or brush on a waterproofing membrane over the whole face. Grout does not stop water—the membrane behind the tile does that job.
Laying Out The Tile Field Before You Cut Anything
Measure the surround’s width and height, then mark the horizontal and vertical midpoints on each wall. Draw level lines for the horizontal course and plumb lines for the vertical ones; these references keep the tile grid true even if the tub or ceiling is slightly off.
Set tile starting with the back wall first, then move to the side walls. That order keeps the corners aligned and hides any cut tiles in less visible spots. For an alcove tub, tile the back wall, then the wall behind the shower, then the third wall last.
Plan your cuts before you mix the first batch of thinset. Faucets, spouts, and showerheads all need holes cut with a wet saw or manual cutter; mark each penetration on the tile face and cut carefully. Most tile stores rent wet saws by the day if you do not own one.
Setting, Grouting, And Sealing The Joints
Spread thinset with a notched trowel, comb it in one direction, and press each tile into place with a slight twist. Plastic spacers keep the grout lines consistent. Let the adhesive cure for the full time printed on the bag—usually about 24 hours—before you walk on the floor or start grouting.
Grout fills the joints between tiles. Press it into every gap with a rubber float, wipe the excess off with a damp sponge, and let it dry completely. Once the grout hardens, seal it with a penetrating sealer to repel water and stains.
The joint between the tub and the first row of tile gets silicone caulk, not grout. That gap flexes as the tub settles and fills with water; grout cracks under that movement. Silicone caulk stays flexible. Matching caulk in the same color as the grout keeps the seam invisible. Fine Homebuilding’s guide on perfecting the tiled tub surround places the caulk step after the grout hardens, and that is the right window—caulking too early traps moisture in the wall.
| Step | Detail | Time Needed |
|---|---|---|
| Demo | Remove old tile and sheetrock down to the studs | 4-6 hours |
| Backer board | Cement board with 1/4-inch gap above the tub rim | 3-4 hours |
| Waterproof | Tape seams, then apply membrane over the full face | 2-3 hours |
| Layout | Level and plumb reference lines from midpoints | 1 hour |
| Set tile | Back wall first, then side walls; spacers for joints | 6-8 hours |
| Cure | Let thinset dry per the bag instructions | 24 hours |
| Grout and seal | Grout, wipe clean, then seal after full dry | 3-4 hours |
| Caulk | Silicone at the tub-to-tile and corner joints | 1 hour |
How High Should The Tile Go?
For a tub with a showerhead, tile must extend at least 5 feet above the tub rim or 6 inches above the showerhead, whichever is higher.
Those numbers are a floor, not a ceiling. Many homeowners tile to the ceiling because it looks finished and costs only a few extra rows of material.
If you are still choosing the tile itself before you buy, our tested best bath tub tile roundup covers the top-rated options for wet surrounds, including slip ratings and durability notes.
FAQs
Can you tile directly over existing tile?
It is possible if the old tile is firmly bonded and the surface is clean, but the added thickness changes the layout around the tub faucet and showerhead. Most pros strip to the studs instead, because a failing bond line under new tile creates an unstable base that cracks grout quickly.
What is the best waterproofing for a tub surround?
A liquid-applied waterproofing membrane over cement backer board is the most common system. It brushes on like thick paint, dries to a rubbery film, and bridges the taped seams. Alternatives include waterproof foam backer boards that need no separate membrane layer.
Why is my grout cracking along the tub edge?
Grout is rigid and cracks when the tub flexes under weight or temperature changes. The tub-to-tile joint needs a flexible sealant, not grout. Scrape out the cracked grout with a utility knife and replace it with a silicone caulk rated for bathrooms.
References & Sources
- This Old House. “How to Tile a Tub Surround.” Details the substrate sequence and cement board requirement.
- Fine Homebuilding. “Perfecting the Tiled Tub Surround.” Covers layout, waterproofing, and joint treatment.
