EZ Able® Resource Guide
Can You Put a Curbless Shower on a Concrete Slab?
Quick answer
Yes, you can put a curbless shower on a concrete slab: either set a low-threshold prefab pan on the slab and bring the finished bathroom floor up to meet it, or saw-cut and recess the slab so the pan or foam sloping kit sits low. Either way, the drain location and the finished floor height decide how much concrete has to move.
Short answer: yes, and you have two ways to do it. You can raise the floor (set a low-threshold prefab shower pan right on the slab and build the bathroom floor up to meet its threshold), or you can recess the slab (saw-cut and chip out the concrete so the pan or a foam sloping kit sits low enough to be flush). Raising the floor is usually less work; recessing gives you a truly level floor everywhere, but it takes a concrete cutter, a plumber, and a careful look at what's inside the slab first.
Why a slab changes the job
On a wood-framed floor, you can drop the subfloor between the joists or notch in a drain without much drama. A slab doesn't give you that room. Three things make it different:
- The drain is already cast in place. Moving a drain on a slab means cutting a trench to the existing line, resetting the trap, and patching. That's plumber work, not tile work.
- You can't easily go lower. Every inch you want the shower floor to drop is an inch of concrete that has to come out. The International Residential Code sets a minimum slab-on-ground thickness of 3-1/2 inches (IRC R506.1), and a lot of residential slabs are close to that, so there isn't much to work with.
- There may be things in the concrete you can't see. Post-tension cables, rebar or mesh, radiant heat tubing, and the vapor barrier underneath all matter before anyone cuts.
The good news: with today's low-profile pans, many slab bathrooms don't need to be cut at all.
Option 1: Raise the floor around a low-threshold pan
This is the method we recommend most often, because it keeps the concrete saw in the truck.
A prefab curbless pan sits directly on the slab. You then build the rest of the bathroom floor (underlayment, setting material and tile) up to the height of the pan's threshold, and butt the tile against it.
The number that matters is your finished floor build-up. Most tile floors finish about 3/4 inch thick, so a pan with a 3/4-inch threshold usually ends up close to flush with the finished tile. If your floor build-up is thicker (say, a leveling layer plus tile), a taller threshold option may line up better. Our step-by-step for this approach is in How to Install a Curbless Shower Without Recessing the Subfloor.
What it takes:
- A solid, level slab. The Best Bath low-profile pan install guide calls for the floor to be within 1/8 inch of level, especially around the drain, with no high spots.
- Access at the drain. Even on a slab, the drain connection needs an opening around the pipe. On a wood subfloor the same guide calls for an 8 x 8 inch box-out; on a slab, your plumber will chip whatever opening the drain assembly needs.
- Planning at the bathroom door. You've raised the bathroom floor by the thickness of your finish, so the transition into the hallway needs a plan (more on doors below).
Option 2: Recess the slab
If the hallway and bathroom must be one continuous level floor, or you're building a tiled curbless shower on a foam sloping kit, recessing is the way to go.
The crew saw-cuts the shower footprint, chips out the concrete to the depth the pan or sloping kit needs, the plumber resets the drain and trap at the new height, and the area is patched and leveled before the shower goes in.
What it takes:
- A green light on the slab. Confirm slab thickness and what's inside it before cutting. If the home has a post-tensioned slab (often marked with a stamp or tag near the garage or in the plans), do not cut without an engineer.
- A plumber. The drain will almost always need to be reset lower.
- A waterproofing plan for the recessed area. The QuickDrain sloping kits list concrete (interior only) as an approved substrate and are set in thin-set, with sheet or liquid waterproofing on top. They replace the traditional mud bed.
Side-by-side: raise the floor vs. recess the slab
| Question | Raise the floor | Recess the slab |
|---|---|---|
| Concrete cutting? | Usually just a small opening at the drain | Saw-cut and chip the whole shower area |
| Who's involved | Installer + plumber for the drain connection | Concrete cutter + plumber + installer |
| Drain | Often stays close to its current spot | Usually reset lower |
| Bathroom door | Floor is raised by the finish thickness; plan the transition | Hallway and bath can stay one level |
| Best fit | Remodels, tub-to-shower conversions, tight schedules | Fully level homes, tiled curbless showers, new builds |
| Biggest risk | Ordering the wrong threshold height | Cutting into post-tension cables, rebar or radiant tubing |
Which EZ Able products fit a slab job?
- Ready-to-use curbless pans (shop curbless ready-to-use pans): fiberglass or acrylic bases with a finished, slip-resistant floor, so there's no floor tile inside the shower. These are the go-to for the raise-the-floor method. For example, the Best Bath 60 x 32 curbless shower pan is pre-leveled (no mortar bed), installs directly on a solid, level floor, offers left, center or right drains, and comes with beveled or square thresholds from 3/4 inch to 2 inches. It typically ships in 5 business days and carries a 30-year limited warranty.
- Pre-sloped pans for tile (shop curbless pre-sloped pans for tile): QuickDrain foam sloping kits for a tiled curbless shower with a linear drain. They're cut-to-size with a utility knife, work over concrete (interior), and skip the mud bed. These are the usual pick when the slab is recessed.
- Ready-to-tile parts (shop ready-to-tile): linear drains, the Level Entry Shower Waterproofing System, and other pieces you build a tiled shower with.
Browse everything at curbless showers. Prefab pans are Made-Upon-Order and can't be returned, so confirm size, drain side and threshold before you order.
Linear drain or center drain on a slab?
On a slab, the drain decides how much concrete comes out.
- Linear drain (along the entry or back wall): the floor slopes in one plane toward the drain, which keeps the entry flat and is easier to tile with large tile. QuickDrain recommends setting the drain parallel to the shower entry for curbless kits. It usually means relocating the drain to the new line, so plan a trench.
- Center drain: the floor slopes from all sides toward the middle. If your existing drain is already near center, a center-drain prefab pan may let you keep it where it is.
For drain sizing and flow, see our guide to the curbless tile shower pan with linear drain.
The threshold: what "flush" and "ADA" really mean
Threshold height is measured against the finished floor, not the slab. That's the single most common mix-up we see.
- ADA 2010, section 608.7 limits the threshold of a roll-in or transfer shower to 1/2 inch high, and section 303 requires any change in level above 1/4 inch to be beveled. So a bare 3/4-inch threshold isn't an ADA roll-in threshold by itself. Once a 3/4-inch tile floor is installed beside it, though, the step from finished floor to shower can come close to zero.
- There's a slab exception in the ADA itself. In existing facilities, a transfer shower may have a threshold up to 2 inches where a 1/2-inch threshold would disturb the structural reinforcement of the floor slab (608.7, exception). It applies to transfer showers only, not roll-ins.
- Private homes aren't required to meet ADA. Many families use the ADA numbers as a good target anyway. If you're building for a commercial or public space, confirm the inside dimensions and finished-floor threshold with us before ordering. A standard roll-in needs at least 30 x 60 inches inside (608.2.2).
More detail: ADA Shower Dimensions & Specifications Guide.
Don't forget the bathroom door
A barrier-free shower doesn't help much if the bathroom door is the barrier. On a slab job, check:
- Door width. The opening has to fit a wheelchair, walker or a helper standing alongside.
- Door height if you've raised the floor, and whether the door still swings clear.
- No new threshold. A raised bathroom floor shouldn't create a step or a lip at the hallway. Taper the transition or bring the hallway up to match.
If you're still choosing between styles, our Walk-In vs. Curbless vs. ADA Showers comparison walks through it.
A 5-step contractor checklist before you cut or order
- Check the slab. Find out its thickness and whether it's post-tensioned. Look for rebar, mesh and radiant tubing before cutting. If it's post-tensioned, call an engineer first.
- Locate the drain. Mark the existing drain and decide whether the pan's drain (left, center, right or linear) can use it or needs a trench.
- Plan the slope. Prefab pans have the slope molded in. For a tiled shower, the sloping kit sets it. Either way, set the drain body level, even if the slab isn't.
- Plan the waterproofing. Prefab pans are the waterproof floor. Tiled showers need a sheet or liquid membrane over the sloping kit and the recessed area.
- Measure the finished floor height. Add up underlayment, setting material and tile, then pick the threshold that matches. Send us that number and the drain location and we'll confirm fit.
Frequently Asked Questions
Click a question below to expand the answer.
Can you put a curbless shower on a concrete slab?
Yes. The simplest way is to set a low-threshold prefab pan directly on the slab and build the bathroom floor up to meet it. Most tile floors finish about 3/4 inch thick, so a 3/4-inch threshold usually ends up close to flush. If the hallway and bathroom must stay one level, the slab can be recessed instead, which takes a concrete cutter and a plumber.
Do I have to cut the slab for a curbless shower?
Not always. With a low-profile prefab pan, you usually only open the concrete around the drain for the plumbing connection, then raise the finished floor to the threshold. You'll need to recess the slab if you want the bathroom and hallway to stay one level, or if you're building a tiled shower on a foam sloping kit with no floor build-up.
What threshold height should I order for a slab?
Match the threshold to your finished floor build-up, not to the bare slab. Add up underlayment, setting material and tile. For a typical 3/4-inch tile floor, a 3/4-inch threshold usually lands near flush. Thicker build-ups may suit a taller threshold option. Send us your floor plan and drain location and we'll confirm before you order, because prefab pans can't be returned.
Is it safe to cut a post-tension slab for a shower?
Not without an engineer. Post-tensioned slabs contain steel cables under very high tension, and cutting one is dangerous and costly to repair. Check the plans or look for a post-tension notice before any saw-cutting. If you can't confirm, choose the raise-the-floor method with a low-threshold pan so you only open a small area at the drain.
Does the ADA allow a higher threshold on a slab?
In one case. The 2010 ADA Standards (608.7) allow a transfer shower in an existing facility to have a threshold up to 2 inches high where a 1/2-inch threshold would disturb the structural reinforcement of the floor slab. Roll-in showers don't get that exception; their threshold is limited to 1/2 inch measured to the finished floor.
Next Steps: Need Help Choosing?
Tell us three things: the slab situation (and whether it's post-tensioned), where the drain is now, and what's going on the finished floor. We'll point you to the pans that fit, and tell you plainly about the ones that don't. Call 877-392-2531, or start with our curbless showers.
Facts reviewed by the EZ Able team. Product specs from the ezable.com product pages and the Best Bath and QuickDrain installation sheets linked there, October 2026. ADA references from the 2010 ADA Standards for Accessible Design (sections 303, 608.2.2 and 608.7). Slab thickness from the International Residential Code, R506.1.
Posted by Jody Fisk, President of EZ Able®. Licensed Michigan residential builder since 1991, helping builders and homeowners get accessible showers right.
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