Elevated solution

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This article was published 16/11/2024 (346 days ago), so information in it may no longer be current.

A basement bathroom remodel becomes complicated when the orientation or position of one of the amenities must change. Older basement bathroom rough plumbing is usually set within concrete. As such, any changes would incur breaking concrete to realign the drainage plumbing, which is of course quite pricey and often cost-prohibitive. Luckily, design requirements with a recent basement bathroom renovation negated the need to bust up concrete, despite repositioning the tub drain location. In retrospect, things all came together quite nicely.

Once the old corner tub had been removed, as well as the old corner walk-in shower along the opposing wall, it was quickly apparent the existing tub drain tie-in location was not ideal for the new standard-size 60-by-30-inch tub. After capping the shower drain and shower water feeds (which would be abandoned), setting the new tub along the back wall created a drain-placement discrepancy, primarily in depth from the back.

Fortunately, and due to the fact the homeowners wanted stair access along one side of the tub platform, the easiest way to introduce stairs and a way to tie-in the new tub drain would be to place the tub at a higher elevation. By doing so, there would be a path below the tub to run new ABS toward the existing tie-in of the old drain location. As such, the tub would be placed atop a base platform that allowed the ABS to run underneath, somewhat like drain pipes running between joists.

With the ABS requirement in mind, setting the elevation of the tub was derived by back measuring the intended height of the tub, while incorporating the stair configuration along the left side of the tub platform. This particular tub was 18-inches high. By framing the base using laminated two-by-fours as “joists” atop the concrete floor on 12-inch centres, and sheathing it with three-quarter-inch plywood, the final height of the tub would be in the vicinity of 22 or 23 inches high.

This was important, because standard stair heights are normally 7½ inches. Therefore, placement of the new tub on a two-by-four base would allow three stair heights, or two steps to reach the top of the tub deck platform.

Once the base was framed, shims were placed where required to ensure the entire base was level (most basement concrete floors have a slope toward a main floor drain). The shims were then affixed to the base framing.

To ensure rigidity below the tub, quick-set concrete was introduced along the concrete floor, and below the main “joists” of the base upon which the tub would be placed. The tub ABS was then configured in the direction of the rough plumb tie-in to the old drain. Once the water feeds to the tub faucet and hand-wand were engaged, the tub was filled to the overflow and fully tested to ensure proper drainage.

The main tub deck framing was achieved using traditional two-by-four framing, with vertical studs set at every 12 inches. The topside elevation of the upper two-by-four cap was set at roughly 1¼ inches below the underside of the tub perimeter lip, which allows for the 5/8-inch plywood sheathing throughout the top deck, as well as the impending 3/8-inch girth of the chosen tile plus thin-set, which can be easily tucked under the tub lip to ensure a proper seal with silicone at the finishing stage, post tile and grout.

To guarantee a solid set of stairs, my deck-building experience prescribed framing that allowed two-by-sixes along the tops of the framework for extra rigidity, subsequently sheathed with 5/8-inch plywood as well.

Although it took a while to calculate the math, the completed stair configuration depicts the intended 7½-inch heights for both stairs, as well as from the top of the upper stair to the top deck of the tub platform. The lower stair (at the same elevation as the inside of the tub) allows easy front-side access into the tub, right of the faucet, while the second inset stair along the left side of the tub allows a strategic entry point, whereby appropriately placed grab bars will assist in both entry to and exit from the tub.

This dual-purpose and functional stair layout also serves to conceal the inconsistencies of the concrete close to the old drain location of the original tub. This design truly solved all the issues, and most importantly, did not require busting up the old concrete floor.

There are usually several ways to tackle a project. Although the traditional approach may have been to re-configure the old drainage location — which would have been invasive and quite costly — an unconventional solution can lead to a creative alternative that revealed the potential for an even better outcome.

In this instance, everything truly came together once the tub elevation was adjusted to a height that allows for an ABS pipe to run below it. This not only allowed tie-in to the existing drainage, the stair design also evolved to conceal the old uneven concrete near the tie-in, which in turn will provide greater functionality for tub access while adding a beautiful esthetic to the entire tub structure.

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