Curbless Shower Guide: What It Takes in an Existing Home

Curbless, low-profile, and standard curb showers compared

The right choice depends on the house as much as on style. A low-profile entry can be a smart compromise when the floor framing makes a full recess difficult, and it still reads as open and modern.

Where the slope comes from: recessing or raising the floor

Even with a thin prefabricated tray, a sloped shower floor needs depth. In a curbless design, that depth usually comes from lowering the subfloor in the shower area so the finished shower floor starts level with the bathroom floor and slopes down to the drain. Schluter describes recessing the shower subfloor as the way to create room for the sloped assembly while keeping the surrounding bathroom floor at its original height.

The alternative is to raise the rest of the bathroom floor to the height of the shower build-up. That can work in a full renovation, but it changes door thresholds, toilet flange height, vanity and counter heights, and the transition into the hallway.

In a wood-framed floor, how the recess is made matters a great deal. The Ontario Building Code only permits limited notches in floor joists: on the top edge, within half the joist depth of the bearing, and no deeper than one-third of the joist depth, unless the joist is made deeper. A shower recess usually sits mid-span, so the answer is not to cut the joists down. Options include manufacturer bracket systems that lower the subfloor between joists without cutting them, or new framing designed for the load.

Those systems have limits. Schluter's recessing brackets, for example, avoid cutting or notching joists but require joist spacing of no more than 19.2 inches on centre and create a recess of 11/16 inch. Which way the joists run, how far they span, and whether they are dimensional lumber or engineered I-joists all shape the approach. On a concrete basement slab, recessing means cutting out concrete around the drain and reworking the plumbing below, which is a different scope altogether.

Linear drain or centre drain in a curbless shower?

Most curbless designs use a linear drain because it lets the floor slope in one direction. Schluter notes that a linear drain can be installed against a wall or at intermediate locations, and that sloping to it on a single plane allows large-format tile to continue from the bathroom floor into the shower.

Linear drain at the back wall. The floor slopes away from the entry toward the far wall, so water moves away from the room and the entry stays level with the bathroom floor. It is a popular layout for exactly that reason.

Linear drain at the entry. A drain across the opening catches water before it reaches the bathroom. It can suit a tight room, but the shower floor then slopes toward the bathroom and the drain grate sits where people step.

Centre drain. A centre drain can still work, but its four-way slope has to blend into a flat bathroom floor at the opening, which usually means mosaic tile in the shower and more careful transitions. For how drain type affects tile, see our guide to the best tile for shower floors.

Waterproofing has to go past the shower opening

A curbed shower has a clear boundary. A curbless shower does not, so water travels farther than people expect: splash off a body, drips from a towel, or a film of water running along the floor when the drain is working hard. Schluter states that industry guidelines recommend waterproofing a minimum of 1 foot beyond the shower area in curbless showers, and recommends protecting the bathroom as a whole because wet and dry areas are not clearly defined.

In practice, many curbless bathrooms are waterproofed across a large part of the floor or the entire floor, with the membrane tied into the shower walls and the drain as one continuous system. Extra membrane on the bathroom floor is a modest addition next to the cost of repairing a soaked subfloor or the ceiling below.

Ask to see the waterproofing plan in writing: where the membrane starts and stops, how it connects to the drain, how seams and corners are treated, and when the assembly will be water-tested before tile. Our guide to tile waterproofing methods explains the membrane options.

Glass, shower size, and keeping water where it belongs

Without a curb, the layout of the shower does the work of containing water. A longer shower, a fixed glass panel, and a shower head aimed away from the opening all help keep spray inside the wet zone. A handheld shower is useful, especially for accessibility, but it also makes it easier to spray water into the room.

Glass should be planned with the floor, not after it. Fixed panels need solid attachment points and hardware that sits correctly where the floor begins to slope. A swinging door has to clear a floor that is not flat, so bring the glass supplier into the conversation before the tile layout is final.

Tile choices that suit a curbless floor

The appeal of a curbless shower is continuity, so many designs run the same large matte porcelain from the bathroom into the shower. That works best with a linear drain and a single-plane slope, so the larger tiles stay flat. Whatever tile you choose has to be rated for wet floor use and have a finish that gives grip when wet.

If you prefer a mosaic shower floor, a change in format at the shower zone can still look intentional when the colour or collection matches the main floor. Either way, align the tile layout with the drain and the glass line so the cuts land in logical places.

Heated floors pair well with curbless showers because a warm floor helps the wet area dry and keeps the whole room comfortable underfoot. Our article on whether heated floor tile is worth it covers the planning details.

Permits, plumbing, and electrical work in Ontario

A curbless shower usually moves or replaces the drain, and it may change the floor framing. Permit requirements are set by each municipality, so confirm the rules before work starts. The City of Kitchener, for example, lists adding or moving plumbing fixtures as work that needs a building permit, while tiling and similar finish work does not. Because changes to floor framing are structural, ask your building department whether your recess method needs a permit or an engineer's review.

Electric floor heating has its own rules in Ontario. The Electrical Safety Authority requires notification for in-floor heating cables and mats and an inspection before they are covered, and the electrical connection belongs with a Licensed Electrical Contractor.

A good tile installer will tell you which parts of the job belong to a plumber, an electrician, or a framer, and who is responsible for permits and inspections, before any demolition begins.

When a curbless shower makes sense, and when it fights the house

Curbless showers make the most sense when the bathroom is already being taken down to the framing, the floor structure allows a recess, and the design benefits from one continuous floor. They are especially worthwhile in main-floor and primary bathrooms where someone may later rely on a walker, a shower seat, or a wheelchair.

They are harder when the joists run the wrong direction or have already been cut for old plumbing, when the room sits over a finished ceiling nobody wants to open, or when the bathroom is too small to contain spray without a curb. In those cases, a low-profile entry often delivers most of the look with far less disruption.

Older homes across Waterloo Region often carry decades of past renovations, and framing under a bathroom may not match what anyone expects. Opening the floor is the only reliable way to know, which is why a curbless quote should explain what happens if the structure needs more work than planned.

Questions to ask before approving a curbless shower quote

Bring these questions to every installer you are comparing. Clear, specific answers are a good sign that the hidden work has been thought through.

What we recommend for a curbless shower in Waterloo Region

If you want a curbless shower, decide early. The recess, drain, and waterproofing have to be designed before demolition is finished, not added once tile is on site. Our usual recommendation is a linear drain with a single-plane slope, waterproofing well past the opening, and a matte porcelain floor that can run through the room.

Moonka Tiles Co. builds custom showers, including curbless and low-profile entries, with the prep and waterproofing planned before the first tile. Learn more about custom shower installation in Kitchener, Waterloo, Cambridge, and Guelph, or send us photos of your bathroom and a rough layout to find out what a curbless shower would involve in your home.