Replacing a tub and shower combo can go smoothly, as a general rule, when three things line up. The replacement suits the opening between the walls. The drain can stay where it sits, or it can be moved to suit the replacement. And the wall around the fixture is planned, not assumed. When one of those doesn’t hold, that’s a question for a designer: ask about reworking the wall or the layout before anything gets ordered.
The order matters. A replacement picked by size alone and checked afterward can reopen the plan. The drain, the opening at the studs and the finished wall all sit around the old fixture, and so can a grab bar. Change the fixture, and any of them may have to change with it.
A Tub and Shower Combo Puts Two Jobs on One Wall
In plain terms, it’s one fixture doing two jobs. The tub and the shower share a single run of wall. So, as a general rule, the walls around the tub end up doing the shower’s work too. They take the spray. That’s why replacing the fixture is more than a tub job — it reaches the tub, the shower and the wall in one go.
The doubling-up is the point of the fixture. In one bathtub maker’s shopping guide, tub showers are described as products that combine the pros of a bathtub and a shower while saving on bathing space. That’s the guide’s own framing. It’s a fair way to think about what you’re replacing: a bath and a shower sharing one footprint.
That’s also why a replacement chosen by size alone can miss. Length and width are the easy part. What decides whether the swap stays simple is the drain end, the opening at the studs, the wall finish and the grab bar. Each of those deserves its own check before the order goes in.
Which End Is the Drain On, and Can It Stay There?
Start at the drain end. The replacement has to suit it. One maker’s product page for a one-piece tub shower lists left-hand and right-hand drain versions to fit your specific bathroom layout. It also lists a version with above-the-floor rough plumbing, which that page says allows easy plumbing installation without having to relocate the existing drain.
How the unit is built matters here too. The description on one maker’s one-piece tub shower page calls it one-piece construction for reliable water containment. That’s the page’s own wording about its product. It isn’t a promise that a fixture will keep water out of your wall, and it doesn’t settle where your drain should sit.
So do two things before anything gets ordered. Note which end of the tub the drain sits at. Then photograph that end and the floor beside it. Picture a bathroom where the old tub drains at the far end and the replacement you like drains at the near one. That’s not something you want to find out on delivery day. Bring the photos to your designer and ask it plainly: can the drain stay where it is, or does it have to move to suit this unit? The answer will shape which units stay on your list.
How Big Is the Opening, and How Does the Replacement Get In?
Measure the opening to the studs. That same shopping guide says bathtubs are typically installed to the bare studs, and that with finished walls in place a measurement must account for wallboard and enclosure thickness. It says adding one-half to three-quarters of an inch to both sides of your measurement should get you closer to the size needed.
Size is only half the question. That one-piece page lists its unit at 60 inches long, 32 inches wide and 78 inches tall. That’s one model’s listing, not a size your bathroom has to take. A piece that tall and that wide raises a second question: how does it get into the room? A one-piece unit is a single piece, so the way in is worth asking about. Ask your designer how a unit of those dimensions would come in. That’s a question for a floor plan, not for a delivery day.
There’s a separate post on what the standard bathtub size means for your alcove, and that’s where the opening gets measured. Work through it first. Then bring the numbers to your designer rather than to a product listing.
Should the Walls Come Built In or Be Finished Around the Tub?
There are two routes. A one-piece unit is made as a single piece, and that page lists one-piece construction. The other route is a separate tub with the wall around it finished as part of the plan. Each one changes what the walls have to do, so ask your designer to lay out both for your room.
The wall finish is a decision of its own, and it doesn’t resolve itself. There’s a separate post on what to ask before you choose shower wall panels over tile, and that’s where the choice gets weighed. Weigh that question there, because the answer can feed back into which route suits this room.
Then ask one more question that’s easy to skip. Where does the soap go? That page lists built-in shelves on its unit. A finished wall can be planned with a place for bottles as well, but it has to be drawn in rather than added afterward. Ask your designer to settle it on the plan.
Where Will the Grab Bar and the Slip-Resistant Floor Go?
The shopping guide says grab bars can be mounted horizontally or vertically, on the back wall, the side walls or near the entrance into the unit. It also describes slip-resistant flooring as a matte or textured finish at the bottom of the unit. That one-piece page lists a textured bottom and an included grab bar.
Where a bar goes is a plan question, and it’s one to answer before the walls close. As a general rule, a grab bar needs a wall built to hold it. Once the wall is finished, changing that can mean opening it back up. So ask your designer how the wall will be built to take a bar, and where that bar would sit.
That answer starts with people. Tell your designer who uses this bathroom day to day. A tub where a toddler gets bathed and a shower where someone steadies themselves point at different plans. The plan can start from that, and the fixture can follow it.
Frequently Asked Questions About Replacing a Tub and Shower Combo
What is a tub-shower combination?
It’s one fixture where the tub and the shower share a single run of wall, so the tub’s walls do the shower’s work as well. A bathtub maker’s shopping guide describes tub showers as products that combine the pros of a bathtub and a shower while saving on bathing space. Replacing one is a wall job as much as a tub job.
How big is a replacement tub-shower unit?
One maker’s product page for a one-piece tub shower lists a single model at 60 inches long, 32 inches wide and 78 inches tall. That’s one model’s listing, not a size your bathroom has to take. A bathtub maker’s shopping guide says bathtubs are typically installed to the bare studs, and that a measurement taken with finished walls must account for wallboard and enclosure thickness. Ask your designer to check the opening.
Can I keep my existing drain when I replace a tub and shower?
It may be possible. One maker’s product page for a one-piece tub shower lists a version with above-the-floor rough plumbing, which it says allows easy plumbing installation without having to relocate the existing drain. Whether that suits your bathroom is a question for your designer and the plans. Note which end the drain sits at, photograph it, and raise it early.
Can a tub and shower have a grab bar?
Yes. A bathtub maker’s shopping guide says grab bars can be mounted horizontally or vertically, on the back wall, the side walls or near the entrance into the unit. One maker’s product page for a one-piece tub shower lists an included grab bar on its unit. Where the bar goes, and how the wall is built to take it, is a plan question for your designer.
Can Solstice help me work out which replacement fits my bathroom?
Yes. Solstice’s designers take time to understand how you use your bathroom day to day, then create a plan that optimizes comfort, function and style. Bring what you’ve gathered: photos of the drain end and the walls, plus the opening measured at the studs. Start the conversation there, with the room in front of you rather than a product listing.
Check the Room Before You Order
Solstice’s bathroom design process starts with how you use the bathroom day to day: the designers build a plan for comfort, function and style, and once the design is set, the installation and project management team carries it out.
If you’re replacing a tub and shower combo, note which end the drain is on, measure the opening at the studs and photograph the walls around it. Then contact Solstice about your bathroom project, so the replacement gets settled on the plan with the rest of the room, before any wall is opened.
