A curbless shower (also called a zero-threshold or wet-room shower) eliminates the traditional curb at the shower entry, creating a flush transition from bathroom floor to shower floor. The look is modern and accessibility-friendly. The build is more demanding than a standard curbed shower: the floor must slope to a linear or hidden drain, structural framing must accommodate the lowered floor, and waterproofing must extend beyond the shower zone.

This guide covers a curbless shower built into a typical residential bathroom on a wood-joist floor. Concrete slab installations follow similar principles.

Before you start

Three things to settle:

1. Floor framing must accommodate the slope. Curbless showers slope the floor in the shower zone toward a drain. With a curbed shower, the slope is contained in the pan; curbless requires the floor framing to be lowered (or built up around it) so the slope ends at the bathroom floor level. Sister-joists or framing modifications often required — engineering may be needed for older homes.

2. Linear drain or centred drain. Linear drain (long slot drain at one wall): only one direction of slope, simpler design. Centred drain: slope from all directions to centre. Linear is more popular in modern designs.

3. Waterproofing extends beyond shower. In a curbless shower, water can travel across the bathroom floor before reaching the drain. Waterproof the entire bathroom floor (not just the shower zone) — Schluter Ditra over plywood, then membrane in shower area.

What you'll need

Tools

Circular saw or jigsaw (for framing modifications)
Drill with bits and driver
Trowel (notched, 1/4 inch)
Mixing paddle and bucket
Float (for mortar bed)
Level (4-foot)

Materials

Pre-formed sloped foam shower pan (Wedi, Schluter Kerdi-Shower-Tray) OR deck mud + waterproofing
Linear drain (Wedi, Schluter, or compatible)
Schluter Kerdi membrane + Kerdi-Band
Schluter Ditra (or DitraXL) for bathroom floor
Cement board (1/2 inch)
Modified thinset (for Ditra and tile)
Sister joists or framing lumber (if structural mods needed)
Tile and grout (per finish)

Linear drain at one wall is the simplest curbless design

Linear drain runs along one wall (typically opposite the entry). Floor slopes from entry toward drain.

One direction of slope simplifies framing and tile work.

Pro tip: place drain at far wall to direct water away from bathroom.

Step-by-step instructions

Plan layout: drain location and slope direction

Linear drain at far wall: simplest. Slope from shower entry to drain.

Or centered drain: slope from all four edges.

Mark on plywood subfloor where drain goes and slope direction.

Modify floor framing to accommodate lowered shower floor

Curbless shower floor sits 1-1.5 inches BELOW bathroom floor level (to allow slope and drain depth).

Sister-joists in the shower area to lower the subfloor (or build up around the shower).

If unfamiliar: hire a structural engineer to provide a stamped plan.

Alternative: skip lowering by using thicker bathroom floor finish (raise everything else).

Install drain and rough-in plumbing

Linear drain: install at planned location, plumbed to existing drain.

Drain top should sit at the lowest point of the planned floor slope.

Rough-in plumbing per code; pressure-test before continuing.

Install pre-formed sloped foam pan OR pour deck mud

Wedi/Kerdi pre-formed pan: drops in, slope built in. Mortar in place.

OR deck mud: mix sand-cement, trowel into shower area, slope to drain at 1/4 inch per foot. Cure 24+ hours.

Apply waterproofing membrane in shower area

Schluter Kerdi: trowel thinset, embed Kerdi sheets over pan and walls.

Or RedGard: paint two coats over pan and cement board walls.

Continuous over pan and 6+ inches up walls.

Special attention to drain seal and corners.

Install Schluter Ditra (or similar) over bathroom floor

Trowel thinset on plywood subfloor.

Lay Ditra mat in thinset, press to bond.

Continues from shower pan area out to the bathroom floor.

Provides decoupling and modest waterproofing for bathroom floor.

Tile shower walls and floor

Tile shower walls with modified thinset over Kerdi.

Tile shower floor: smaller tiles (2 inch or mosaic) work better on slope, allowing the tile grout joints to follow the slope.

Use tile spacers consistent with rest of bathroom.

Tile bathroom floor over Ditra

Same tile (or coordinated) over Ditra mat in rest of bathroom.

Verify tile transitions cleanly from shower floor to bathroom floor.

Floor should appear continuous — no curb.

Grout and seal

Grout shower walls and floor with mould-resistant grout (or epoxy grout).

Wait 24-72 hours for cure.

Seal grout (most non-epoxy grouts need sealing).

Silicone sealant in corners (where wall meets floor) — silicone, not grout.

Install glass enclosure (if applicable)

Frameless glass panel along shower opening.

Glass installer measures and installs after tile is set.

Glass anchors to wall or pony wall on one side; sometimes free-standing on floor.

Splash-block or seal at floor edge of glass.

Common mistakes that cost you

Floor not lowered for shower zone. Curb forms at edge. Plan framing carefully.
Insufficient slope. Water pools, doesn't drain. 1/4 inch per foot minimum.
Waterproofing only in shower zone. Water travels across bathroom floor to drain. Waterproof entire floor.
Linear drain at entry, not far wall. Water flows toward bathroom, not away. Drain at far wall.
Skipping the flood test. Find leaks after tiling. Always test before tile.

Frequently asked questions

Curbless vs traditional curbed shower?

Curbless: modern look, accessibility-friendly, harder to build.

Curbed: traditional, easier waterproofing (curb prevents water spread), simpler framing.

Curbless is increasingly popular in modern bathroom design.

What's the slope requirement?

1/4 inch per foot (1/2 inch in 24 inches) minimum.

Some prefer 3/8 per foot for faster drainage.

Less than 1/4 per foot: water pools.

Can I retrofit an existing bathroom to curbless?

Yes, but requires opening the floor framing and modifying joists.

Older homes: structural assessment and engineer recommended.

Cost drivers: extent of framing changes, drain relocation, waterproofing, and finish selections. We provide a detailed written breakdown before work begins.

When to call us instead

Curbless showers are a signature of modern bathroom design. Our team handles framing modifications, waterproofing, and finishes as one fixed-price scope.

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