More than ever, residential bathrooms are substituting bathtubs for the practicality and sensibility of walk-in showers. Along with this shift comes a greater emphasis on the detailing of showers. And when it comes to design that is authentic to our time, (also known as modernism), this often leads to smarter, more attenuated design solutions. One of the most satisfying details we’ve developed for bathrooms lately is the curbless shower. Under the right circumstances, and with some thoughtful planning, the curb can be eliminated without reducing the functionality of a shower. (All images by Build LLC.)
There are several reasons to lose the shower curb. A curbless shower means cleaner lines in the bathroom: there’s less visual clutter, there is greater ease of use with the shower, fewer nooks and crannies to clean, and the shower becomes highly accessible. The methods for achieving this vary and today’s post covers just one technique, but it’s the one we like best and the one we’re designing and building for our current projects.
The primary move is a structural drop in the floor framing to accommodate the shower slope. This change in floor framing (or slab in some conditions) should be considered early on in the project so that the appropriate information can be coordinated with the structural engineer.
As 12” deep joists (11-1/4” for sawn lumber or 11-7/8” for TJIs) are a typical application with floor framing, we find 2x8s to be well suited under the shower floor in general. Note that each situation has its own load factors and needs to be engineered independently.
This 4” floor drop is then lined with a single-ply water proof membrane and filled with a concrete slab sloped to a single trough drain at one end.
We’ll typically include a slight valley down the middle to center the water on its way to the trough. The trough is also sloped in both directions (and perpendicular to the shower slope) to direct water to the drain line in the center. Because the floor slopes are large and orthogonal, the tiles don’t need to be cut into funny little 45 degree angles (a pet peeve of ours).
This system allows the shower floor to align with the bathroom floor and, depending on how the shower heads are arranged, can work with or without a glass partition or door.
There are a few additional (and optional) detailing moves that can enhance the curbless shower. While we typically stick with the same tile at the bathroom floor and the shower floor, we’ll often change the shower tile to a smaller geometry. For instance the bathroom floor may be 12” x 12” tiles whereas the shower tile may switch to 4” x 4” tiles. The increased grout joins in the shower provide a more appropriate scale to the shower and offer more grip to the floor surface. The trough drain can also be outfitted with a stainless steel cover plate to conceal the drain and keep the surface of the shower floor uninterrupted.
Several supplementary posts on bathroom, shower, and tile design also apply to curbless showers. We recommend our guide to selecting tile, lessons in tile, important shower details, and our favorite plumbing fixtures.
Kevin Eckert, founding partner of Build LLC, writes Build Blog,which can be seen occasionally on Custom Home's website.