What's the difference between a curbless shower and a low-threshold shower, and which works better in older Toronto homes?

A curbless shower has absolutely no step or barrier at the entry — the bathroom floor transitions seamlessly into the shower floor at the same level — while a low-threshold shower has a small raised edge (typically 1/2 to 1-1/2 inches) that provides a minimal water barrier without the standard 4–6 inch curb. Both are dramatic upgrades from the traditional shower curb, but they have different structural requirements, costs, and practical considerations that are especially relevant in older GTA homes.

A true curbless shower requires the shower floor to slope toward the drain while the surrounding bathroom floor remains level, which means the shower floor must be recessed below the bathroom floor level. This is achieved by modifying the floor framing — notching or recessing the subfloor and joists in the shower area to create the necessary slope (typically 1/4 inch per foot toward the drain). In new construction or ground-floor renovations with accessible floor framing, this is straightforward. In older Toronto homes — especially second-floor bathrooms in post-war bungalows and Victorian houses — recessing the floor can be complex because it requires modifying floor joists that may also be carrying loads from the room below.

Curbless showers almost always use a linear drain positioned at one edge of the shower (typically the entry side or against the back wall), which simplifies the floor slope to a single plane rather than the four-way slope required for a centre drain. A quality linear drain system (Schluter Kerdi-Line, Infinity Drain, or similar) costs $400–$1,200 for the drain body and grate, compared to $50–$150 for a standard centre drain. Total installed cost for a curbless shower in the GTA runs $7,000–$15,000 including floor modification, waterproofing, tile, linear drain, and glass panel.

A low-threshold shower is a more practical compromise for many older Toronto homes. Instead of eliminating the barrier entirely, the threshold is reduced to a minimal lip — just enough to manage water without creating a significant step. This can often be achieved without modifying floor joists because a small amount of slope can be created within the thickness of the mortar bed and tile assembly on top of the existing subfloor. The low-threshold approach uses conventional waterproofing methods and can work with either a centre drain or a linear drain. Installed cost is typically $5,000–$10,000 — closer to a standard custom tiled shower.

Which Works Better in Older Toronto Homes?

For most pre-1970 Toronto homes — the post-war bungalows in Scarborough, North York, and Etobicoke, the Edwardian and Victorian homes in central Toronto, and the mid-century split-levels across the inner suburbs — a low-threshold shower is usually the more practical choice. The floor framing in these homes was not designed to be modified for recessed shower pans, and the joists may be undersized by modern standards. Cutting into or notching these joists to create a curbless recess can compromise structural integrity unless a structural engineer confirms the modification is safe.

A true curbless shower works best in these older homes when the bathroom is on the ground floor or basement level where the floor framing is more accessible and the subfloor can be more easily modified. Ground-floor bathrooms in bungalows are excellent candidates for curbless conversions, and basement bathrooms built on concrete slabs can accommodate curbless drains by cutting into the concrete — though this requires careful planning around the existing plumbing rough-in and weeping tile.

Water Management Considerations

The biggest practical concern with curbless showers is water containment. Without any barrier, water can flow out of the shower area onto the bathroom floor if the floor slope is not precise, if the shower spray pattern is wide, or if the shower area is too small. The minimum recommended size for a curbless shower is 36 x 48 inches, but 36 x 60 inches or larger is strongly preferred to keep water within the shower zone. A fixed glass panel at the entry (rather than a full enclosure) is the most common approach — it deflects spray while maintaining the open, accessible feel.

Proper waterproofing is absolutely critical for both options. The entire shower floor and walls must have a continuous waterproof membrane — Schluter Kerdi, Laticrete Hydro Ban, or an equivalent system — extending up the walls at least 6 inches above the showerhead rough-in height. For curbless showers, the waterproofing must extend across the transition between the shower area and the bathroom floor to prevent water migration under the tile.

If accessibility is the primary motivation — aging in place, wheelchair access, or mobility considerations — a true curbless shower with a wide entry is the gold standard and may be worth the additional cost and structural modification. If the goal is aesthetic (the clean, modern look) and the home's floor framing makes a full curbless conversion impractical, a well-executed low-threshold shower looks nearly identical and functions excellently for most homeowners.