Custom Curbless / Walk-In Shower
The master remodel where the homeowner is planning to age in place in this house and the new shower has to go in curbless because a one-inch curb at age 78 is the difference between a daily-used shower and a weekly one. The Mercer Island remodel where the design call is the modern wet-room look — no curb, linear drain, large-format porcelain walls reading like slab, frameless glass at the entry. The Capitol Hill condo where the wheelchair-rollover access for an adult child is the requirement and the rest of the bathroom is being designed around that center constraint. The downtown Bellevue penthouse where the architectural intent is the spa-resort wet-room aesthetic and the curbless shower is the center of it. A curbless walk-in shower removes the curb that defined the shower footprint in the traditional design and replaces it with a recessed mortar pan sloped to a linear or trench drain — the surrounding bathroom floor sits at the level the shower pan steps down from, the waterproofing membrane extends beyond the shower footprint into the surrounding floor for splash containment, and a single frameless tempered-glass panel handles the visual separation without a door to swing open. Done right, it lasts 30 years and is the most accessibility-forward shower design available. Done wrong — wrong slope, wrong waterproofing wrap-out, drain undersized for the flow rate — it leaks into the surrounding floor on every use. Handis self-performs every step end to end. From $8,000 for a single-wall walk-in with a mortar pan and a KERDI-LINE linear drain up to $16,000 for a three-wall walk-in with a built-in bench, stone-tile walls, and a curbless mortar pan tied into a custom-cut slab subfloor. The in-wall mixer rough-in and any drain-line relocation sub to a licensed Washington L&I plumber.
Service
What a Custom Curbless Walk-In Shower Build Includes
A custom curbless walk-in shower is the accessibility-forward shower build — no curb to step over at the entry, a recessed mortar pan sloped to a linear or center drain, full Schluter KERDI or Wedi sheet-membrane waterproofing tied into the surrounding bathroom floor for splash containment, and a frameless tempered-glass panel at the entry for visual separation without a door. Structural assessment (whether the shower joists can be dropped or the surrounding floor built up to recess the pan), substrate prep, recessed mortar-bed pan with the slope built in, full waterproofing wrap-out into the surrounding floor, every tile, every grout joint, every seam-seal. Handis self-performs every tile-trade and membrane step end to end. The in-wall mixer rough-in and any drain-line relocation sub to a licensed Washington L&I plumber.
Why Curbless — and the Structural Reality
Curbless is the aging-in-place, wheelchair-accessibility, and modern wet-room design call. No curb to step over means the shower remains usable as the homeowner ages, the bathroom reads larger (the curb is a visual interruption the eye reads as a wall), and the design intent reads as resort-spa rather than as residential bathroom. The structural reality is that curbless requires the shower pan to sit recessed below the surrounding bathroom floor level so the slope to the drain can be built in without a curb. On a slab-on-grade bathroom (concrete subfloor) this is a saw-cut and recess of the existing slab — straightforward and bounded. On a wood-frame bathroom (joist subfloor) this requires either dropping the joists under the shower footprint to recess the pan or building the surrounding floor up to match the unrecessed pan level — both add framing cost and time. We confirm the structural picture on the booking call and the on-site measurement before quoting curbless.
Linear Drain or Center Drain
Linear drain (Schluter KERDI-LINE, Infinity Drain, ACO Quartz) — a long narrow trench drain that sits at the back of the shower against the wall (or in line with the wet-wall corner on three-wall walk-ins). The shower pan slopes in a single direction (toward the back wall) at 1/4 inch per foot. Cleaner sightlines (no center drain breaking up the floor pattern), easier large-format tile install (the slope is uniform so the tiles do not require diagonal cuts at a center drain), and the modern wet-room look. Center drain — a standard 4-inch round drain at the geometric center of the pan. Four-way slope from the perimeter to the center, requires smaller-format tile on the pan (penny round, hex, or 4x4 mosaic) to follow the four-direction slope without lippage. We recommend linear drain on most curbless builds; center drain when the pan footprint is small and a single-direction slope does not work geometrically.
Substrate — Slab Saw-Cut or Joist Drop
Slab-on-grade bathroom (concrete subfloor) — we saw-cut the existing slab to the recess depth needed for the mortar pan (typically 2-1/2 to 3 inches below the surrounding floor level), break out the cut, and pour a recessed sloped pre-pan in the cavity. The remaining slab is the surrounding-floor reference level. Wood-frame bathroom (joist subfloor) — we either drop the joists under the shower footprint (sister new joists at the lower elevation, cut the existing joists to match) or build the surrounding floor up to the unrecessed pan level (3/4-inch plywood plus a Ditra layer on the surrounding floor, the pan at the original subfloor level). Joist drop is more work but preserves the surrounding-floor elevation; floor build-up is less work but raises the surrounding floor 3/4 inch (which affects baseboard, door swing, and any threshold transitions).
Mortar-Bed Pan Sloped Toward the Drain
Linear-drain pans get a single-direction slope at 1/4 inch per foot from the entry to the drain at the back. Center-drain pans get four-way slopes from the perimeter to the center. Either way the slope is built into the deck-mud topping over a sloped pre-pan, a 40-mil PVC pan liner running 6 inches up the walls behind the cement board, and the deck-mud topping cures 24 to 48 hours before any membrane bonds over.
Full Schluter KERDI or Wedi Sheet-Membrane Waterproofing — and Wrap-Out
Standard KERDI install on the walls and the pan, KERDI-BAND on every seam and inside corner, KERDI-SEAL-PS at every penetration. The critical curbless detail is the wrap-out — the waterproofing membrane extends beyond the shower footprint into the surrounding bathroom floor for at least 12 inches on every side that does not abut a wall. This catches splash that escapes the shower footprint (curbless showers generate more splash than curbed because no curb interrupts the splash trajectory) and protects the surrounding flooring substrate. We use Schluter Ditra in the surrounding floor area connected directly to the shower KERDI so the membrane continuity is uninterrupted.
Tile Setting — Large-Format Porcelain or Honed Natural Stone
Walk-in shower walls almost always set in large-format porcelain (12x24, 18x36, 24x48) for the modern wet-room look or in honed natural stone (Carrara, Calacatta, travertine, limestone) for the premium spa look. Both require the substrate flat to within 1/8 inch over 10 feet. Large-format porcelain sets with medium-bed LFT thinset (Mapei Ultraflex LFT, Ardex X77) on a 1/2-inch by 1/2-inch notched trowel with MLT lippage clips on every joint. Natural stone sets with white Mapei Granirapid thinset (no mineral-line bleed through translucent stone) and unsanded grout. The shower-pan tile is typically penny-round or hex porcelain mosaic for slip resistance and pan-slope follow (mosaic floors handle 1/4-inch-per-foot slope better than larger tiles).
Frameless Glass Panel at the Entry
Curbless walk-ins almost always finish with a single frameless tempered-glass panel at the entry — not a door, just a fixed panel that handles the visual separation between the shower and the bathroom. The panel sits in a U-clamp wall bracket on the wet-wall side and a CRL channel along the floor or a side channel on the entry side. 3/8 inch tempered glass standard, 1/2 inch for larger panels. The custom-glass lead time is 2 to 3 weeks after the install measurement.
How a Custom Curbless Walk-In Shower Build Works
Eight sequential steps from the structural assessment through the final sealer pass — the actual sequence Handis runs on every custom curbless walk-in shower build.
Structural Assessment and Subfloor Plan
Walk the existing bathroom on the booking call and the on-site measurement. Determine whether the subfloor is slab-on-grade (concrete, saw-cut to recess), wood-joist (drop joists or build up surrounding floor), or already recessed (rare on a remodel). Confirm the drain location (existing center vs new linear) and any drain-line relocation work. Quote reflects the structural scope.
Saw-Cut Slab or Joist Drop
Slab-on-grade — saw-cut the existing concrete to the recess depth (typically 2-1/2 to 3 inches), break out the cut, prep for the new pre-pan. Wood-joist — sister new joists at the lower elevation under the shower footprint, cut existing joists to match, install new subfloor at the recessed level. Either way the structural prep is done before any waterproofing.
Mortar-Bed Pan with Single-Direction or Four-Way Slope
Linear-drain pans get a single-direction slope from the entry to the back drain at 1/4 inch per foot. Center-drain pans get four-way slopes from the perimeter to the center. Sloped pre-pan in deck mud over a 40-mil PVC pan liner running 6 inches up the walls. Deck-mud topping cures 24 to 48 hours before the membrane.
Schluter KERDI or Wedi Sheet Membrane on Walls and Pan
Orange KERDI polypropylene-fleece sheet bonded with unmodified thinset to every cement-board wall and the pan topping. KERDI-BAND on every seam and inside corner. KERDI-SEAL-PS at every penetration. KERDI-DRAIN or KERDI-LINE bonding flange tied into the pan membrane. The membrane sits 24 hours.
Membrane Wrap-Out Into the Surrounding Floor
The critical curbless detail — KERDI on the shower walls and pan transitions to Schluter Ditra on the surrounding bathroom floor for at least 12 inches beyond the shower footprint on every side that does not abut a wall. The membrane continuity is uninterrupted. Catches the higher splash a curbless shower generates without exposing the surrounding-floor substrate.
Niche and Bench Wrapped Into the Membrane
Pre-formed KERDI-BOARD niches foamed into stud-bay cut-outs and seam-sealed. Built-in benches framed with treated lumber, cement-boarded, KERDI'd on every face, seat-tiled. Niche floor sloped 1/8 inch to the front for water shedding.
Tile Setting — Large-Format Porcelain or Honed Stone Walls, Mosaic Pan
Walk-in walls in large-format porcelain (12x24 through 24x48 with medium-bed LFT thinset and MLT lippage clips) or honed natural stone (Carrara, Calacatta, travertine, limestone with white Mapei Granirapid thinset and unsanded grout). Pan in penny-round, hex, or matched mosaic for slip resistance and pan-slope follow. Grout matched to design intent. Cures.
Frameless Glass Panel and Final Sealer
Custom-measured frameless tempered-glass panel installed at the entry — 3/8 inch standard, 1/2 inch on larger panels. Two coats of penetrating sealer (TileLab SurfaceGard, Aqua Mix Sealer's Choice Gold for porcelain; Miracle 511 Impregnator for natural stone) after grout cures 24 to 72 hours. Second coat after the first cures 24 hours.
Custom Curbless Walk-In Shower Pricing
Final pricing depends on the subfloor type (slab-on-grade saw-cut vs wood-joist drop or build-up — joist work adds the most variability), the shower footprint, the wall-tile material (large-format porcelain vs natural stone), the niche and bench scope, the drain choice (linear or center), and whether the in-wall mixer is being replaced (licensed-plumber sub). Glass enclosure is line-itemed on every quote as a custom-measured panel. Request a free estimate for an accurate quote.
Tell us the bathroom subfloor type (slab or joist), the shower footprint, the wall-tile material, and the drain preference (linear or center) — we will quote the curbless build with full KERDI wrap-out as standard.
Why Handis for Custom Curbless / Walk-In Showers
A curbless walk-in shower is the project where the difference between a 30-year install and a 10-year one is invisible behind two specific details — the recessed-pan slope and the membrane wrap-out into the surrounding floor. Done wrong, a curbless shower sends water under the surrounding flooring substrate on every use, and the failure mode shows up as a damp spot in the bedroom ceiling below or a soft spot in the bathroom floor outside the shower 18 to 36 months in. Done right, with the slope verified to 1/4 inch per foot in the right direction and the KERDI membrane extending at least 12 inches beyond the shower footprint into a connected Ditra layer on the surrounding floor, a curbless shower outlasts a curbed install. Handis does both details as non-negotiable standard scope on every curbless build. The wrap-out is what makes curbless work; the wrap-out is what most installers cut to save a day.
Membrane wrap-out at least 12 inches into the surrounding bathroom floor
The non-negotiable curbless detail. KERDI on the shower walls and pan transitions to Schluter Ditra on the surrounding bathroom floor for at least 12 inches beyond the shower footprint on every side that does not abut a wall. The membrane continuity is uninterrupted. Curbless showers generate more splash than curbed (no curb to interrupt the splash trajectory) and the surrounding-floor substrate has to be protected. The wrap-out is what makes curbless last 30 years; skipping the wrap-out is the single most-common reason a five-figure curbless install fails inside 36 months.
Structural assessment before quoting
Slab-on-grade bathrooms (concrete subfloor) — saw-cut and recess the existing slab to the pan depth (typically 2-1/2 to 3 inches), straightforward scope. Wood-frame bathrooms (joist subfloor) — either drop the joists under the shower footprint or build up the surrounding floor to match the unrecessed pan. Both work, both add cost. We confirm the subfloor type on the booking call and the structural scope on the on-site measurement before any quote goes out.
Linear drain or center drain — chosen to fit the geometry
Linear drain (Schluter KERDI-LINE, Infinity Drain) for most curbless walk-ins — single-direction slope at 1/4 inch per foot toward the back wall, cleaner sightlines, easier large-format tile install, modern wet-room look. Center drain (Schluter KERDI-DRAIN) when the pan footprint is small and a single-direction slope does not work geometrically — four-way slope to the center, mosaic shower-floor tile required to follow the four-direction slope without lippage.
Mortar-bed pan with the slope built in, verified before membrane
Sloped pre-pan in deck mud over a 40-mil PVC pan liner. Deck-mud topping with the slope built in to 1/4 inch per foot toward the drain. Slope verified with a 4-foot level in three directions before any membrane wraps over the topping. The deck-mud topping cures 24 to 48 hours. On linear-drain pans the slope is in one direction (entry to back); on center-drain pans the slope is four-way from the perimeter to the center.
Full Schluter KERDI on every wall and the pan, KERDI-BAND on every seam
Same membrane assembly as every Handis custom shower build. Orange KERDI polypropylene-fleece sheet bonded with unmodified thinset to every cement-board surface. KERDI-BAND on every seam and inside corner. KERDI-SEAL-PS at every penetration. KERDI-DRAIN or KERDI-LINE bonding flange tied into the pan membrane. Curb wrapped — wait, there is no curb. That is the point.
Estimate
Tell us the bathroom subfloor type (slab-on-grade concrete, wood-frame joist, or unknown — we will check on the measurement), the shower footprint, the wall-tile material preference (large-format porcelain or natural stone), the drain preference (linear at the back or center), the niche and bench scope, whether the in-wall mixer is staying or being replaced, whether the existing drain location stays or relocates, and any accessibility-forward requirements (wheelchair rollover, grab-bar locations, bench dimensions). We send a clear estimate with full KERDI waterproofing and the surrounding-floor wrap-out as standard scope.
Customer Reviews
Recent custom curbless walk-in shower reviews from verified Handis customers.
Curbless walk-in shower in our master remodel. Curbless mortar pan with a linear drain, full Schluter waterproofing tied into the bathroom floor with Ditra on the surrounding-floor wrap-out, large-format porcelain on the walls, frameless glass at the entry. The aging-in-place wheelchair-rollover access we wanted is in there too. Handis sequenced the plumber for the valve cleanly. The whole project finished on the calendar they gave us.
Curbless wet-room walk-in in our Mercer Island remodel — 24x48 porcelain walls reading almost like slabs, a Schluter KERDI-LINE linear drain across the back wall, frameless tempered glass at the entry. Handis did a joist drop under the shower footprint to recess the pan without building up the surrounding floor — preserved the existing baseboard and door swings. The bathroom reads as a spa.
Curbless walk-in on a slab-on-grade downstairs bathroom in our Capitol Hill condo. Handis saw-cut the slab to recess the pan, set the mortar pan with single-direction slope to the linear drain, full KERDI wrap-out into the surrounding floor as Ditra. Honed Carrara walls and a Carrara penny-round mosaic shower floor. The whole bathroom rebuilt around the curbless shower. Eighteen months in, dead-dry surrounding floor and tight seal at the drain.
Wheelchair-accessible curbless shower for our adult child in our Bellevue split-level. Handis worked with the occupational therapist on the bench dimensions, grab-bar locations, and the drain placement that keeps the wheelchair rollover path dry. Built-in bench framed and KERDI-wrapped, large-format porcelain walls, slip-resistant porcelain mosaic floor. The functional requirements were the design driver and the install reads as intentional design, not as compromise.
Curbless walk-in upgrade from a 1990s curbed shower in our 1985 split-level. Handis built up the surrounding floor with a 3/4-inch plywood layer rather than dropping the joists (faster, cheaper, but cost us a 3/4-inch baseboard rework which we knew about up front). Mortar pan, linear drain, full KERDI wrap-out, 18x36 porcelain walls. Eight working days. We saved $1,500 over the joist-drop option because the structural reality of our particular bathroom made the build-up the right call.
Frequently Asked Questions
Common questions about Handis custom curbless walk-in shower builds — structural prep, drain choices, waterproofing wrap-out, accessibility, and pricing.