How to Install a Shower Curb Kit
Part of our Showers guides.
Curb kits replace a traditional mortar bed with a pre-sloped foam base. Waterproofing details decide whether it lasts. Turn off the water (and power at the breaker for anything electrical) before starting, and follow the product manual where it differs from these general steps.
| Time | 1-2 days |
|---|---|
| Difficulty | Hard |
| Tools | Notched trowel, thinset, utility knife, sealant, level |
Step by step
- Prepare subfloor. Clean, flat, solid; cut the drain hole.
- Dry fit. Trim the pan if the kit allows.
- Install drain flange. Bond to the drain pipe (ABS or PVC to match).
- Set the pan. Spread thinset and bed the pan.
- Set the curb. Cut and bed the curb.
- Waterproof. Apply membrane and banding over seams, corners and the drain.
- Flood test. Plug the drain and fill for 24 hours; check for leaks.
- Tile. Tile floor and walls after a successful test.
Tips & common mistakes
- Don't skip the flood test.
- Use the sealant specified by the kit.
Choosing ABS or PVC
Look at your drain pipe: black is ABS, white is PVC. Use the matching flange and the correct cement. Some codes prohibit mixing materials at this joint without an approved transition fitting.
Setting the foam pan
Use modified thinset as specified by the kit and a notched trowel. Comb the thinset in one direction, press the pan in and walk on it (on boards) to ensure full contact. Hollow spots under a foam pan lead to cracked tiles later.
Waterproofing details that fail most often
- Inside corners: use the preformed corners or banding with generous overlap.
- Curb ends: the curb-to-wall joints need overlapping banding.
- Drain: the membrane must bond to the drain flange exactly as the kit shows.
- Pipe penetrations: seal valve and shower arm holes with collars or sealant.
The flood test
Plug the drain, fill the pan to just below the curb and mark the water level. Wait 24 hours. If the level hasn't dropped (apart from a little evaporation) and there's no moisture below, you're ready to tile.
Tiling the sloped floor
Small tiles (2x2 inch mosaics) follow the slope best and give grip. Large tiles need cutting into a "envelope" pattern around a center drain; a linear drain allows larger tiles on a single slope.
Frequently asked questions
How long before I can tile?
After the waterproofing cures and passes the flood test, typically a day or more.
Can I install a curb kit on plywood?
Yes, if the subfloor is solid and flat; follow the kit's substrate guidance.
How long before I can shower?
After tiling and grout cure, typically several days.
Do curb kits include tile?
No, tile and grout are separate.
Can I use a linear drain?
Some kits support linear drains; check compatibility.