Quick answer for the job site: A shower curb has to do three things. It has to shed water back into the pan, keep the waterproofing continuous from the pan over the curb and up the jambs, and give the tile a clean, protected edge. Slope the curb top toward the shower, wrap the membrane over the curb and into the wall waterproofing with the overlaps the manufacturer requires, and finish exposed edges with a metal profile sized to the tile thickness. Most curb callbacks trace back to one of those three things.
Related Pro reading: build a waterproof shower enclosure with Schluter and managing moisture in tile showers. For clients, send shower waterproofing explained.
Curb pitch: the top must drain inward
- Slope the curb top toward the pan. TCNA Handbook details and most system makers call for the top of the curb to pitch into the shower so splash on the curb drains back in, not onto the bathroom floor. Set the slope in the curb build or the mortar, not by buttering the tile thicker on one side.
- Pan slope. ANSI A108.01 / TCNA shower details call for a minimum of 1/4" per foot slope to the drain on the shower floor. Check the curb-side edge of the pan most carefully, because a flat spot along the curb is where water sits.
- Height. Follow your local plumbing code for threshold height and the waterproofing system's details. For curbless or low-threshold builds, use a linear drain or a recessed-pan system made for it.
- Glass. Ask the glass installer before tile goes on. Fixed panels and door sweeps may need a specific curb width or a flat strip. If you change the pitch after tile, the glass won't fit.
Waterproofing tie-in over the curb
Sheet membrane systems
Run the membrane from the pan up the inside face of the curb, over the top, and down the outside face. Lap the wall membrane down onto the pan and curb per the manufacturer's minimum overlap, usually with band or seam tape at the inside corners. Use preformed inside and outside corners at the curb-to-jamb transitions instead of folding and slitting the sheet. Avoid fasteners through the curb top. If the system's curb uses them, seal them as the manufacturer instructs.
Liquid-applied membranes
Embed reinforcing fabric at every change of plane, including curb to pan, curb to jamb, and the outside curb corners. Apply to the manufacturer's wet-film thickness and cure time, then verify the film thickness. Coat the whole curb on all sides, including the outside face down to the bathroom floor.
Traditional mud pan with a PVC liner
The liner goes up and over the curb and is folded at the corners, not cut. Don't nail through the liner on the curb top. Set dam corners at the jambs. Flood test the pan before setting tile on any system, following the manufacturer's procedure and local requirements.
Stock from waterproofing (for example KERDI-BAND 5" strip, TEC 316 HydraFlex, TEC waterproofing mesh, or Richpan 1040 PVC liner). Get drains and pan parts from shower systems and shower drains. Don't mix systems. Membrane, band, and drain should all be from the same system so the warranty holds.
Edge trim: finishing the curb
- Size the profile to the tile. Match the trim height to the tile thickness plus the thinset bed. A profile that's too short leaves a sharp tile edge, and one that's too tall leaves a lip that catches water.
- Where it goes. The usual spots are the outside top edge of the curb and the exposed vertical edges at the jambs. Embed the anchoring leg in thinset with full coverage behind it.
- Waterproofing. Set trim over the membrane, never through it.
- Grout joint. Leave a grout joint between the tile and the profile, the same as between tiles.
- Finish. Brushed nickel, chrome, brass, and color-coated aluminum let you match fixtures. Examples in stock: Schluter JOLLY 3/8" brushed nickel, JOLLY 1/2" brushed nickel, and SCHIENE 3/8" satin anodized aluminum. Browse transitions and edge trim or use a matching bullnose if the tile series has one.
Grout and movement joints on the curb
- The inside corners where the curb meets the pan and the walls are changes of plane. Per TCNA EJ171, these get a flexible sealant, not grout. Use a color-matched sealant from caulk.
- For the field joints, pick a grout for wet areas. High-performance or epoxy grouts resist staining on a curb top that sees soap and standing water. Browse grout (for example TEC Power Grout 550). Client wondering about epoxy? Send them epoxy vs cement grout.
- For the curb top, use a full piece or a slab cap so there's no seam running down the middle. If you need joints, keep them perpendicular to the curb so water doesn't sit in them.
Curb checklist before you leave the job
- The curb top pitches into the shower. Check with a level.
- The membrane is continuous from the pan, over the curb, and up the jambs, with overlaps per the manufacturer.
- No fasteners go through the waterproofing on the curb top.
- The flood test passed and is documented.
- Trim is sized to the tile, fully bedded, with a grout joint at the profile.
- Change-of-plane joints are sealed with sealant, not grout.
- The glass installer has confirmed the curb width and pitch.
Frequently asked questions
How much should a shower curb top slope?
Enough that water runs back into the shower. Follow the TCNA detail and your waterproofing manufacturer's instructions, and set the slope in the curb build or mortar so the tile follows it.
Should I nail through the liner on top of the curb?
No. Fasteners through the waterproofing on the curb top are a common leak path. Use the curb system's own method or the bonded-membrane approach.
Grout or caulk where the curb meets the wall?
Sealant. Inside corners are changes of plane, and TCNA EJ171 calls for movement joints there.
What height edge trim do I need?
Match the trim height to the tile thickness plus the thinset bed. Measure the tile you're setting, and check the profile's listed height on the product page.
Can I mix brands of membrane and drain?
Avoid it. Most system warranties require compatible components from the same manufacturer.
Talk to the Trade Pro desk
Bring your plans to a Tile Outlets of America showroom in Tampa, Fort Myers, or Sarasota, or call 1-844-TOA-TILE. Our Trade Pro team can pull current stock and help you match tile, setting materials, and trim on one ticket. Want to check color and texture before you commit? Order a one-piece sample from any product page.