Two tub-to-shower conversion quotes for the same bathroom can sit thousands of dollars apart, and both can be honest. The gap comes down to one question worth asking of every quote: does the floor get opened?
An acrylic or composite pan set over the old tub footprint is the lighter job. A tiled walk-in shower on a new pan, with the drain reworked and enlarged, is the heavier one. Glass, niches, tile and fixtures move the price within each route, but the floor decides which kind of project you are buying. We don’t publish price ranges for this work, because the contractor who performs the conversion prices it from your bathroom’s actual conditions. What we can do is show you what drives the number, so you can compare quotes on the same scope.
Four Routes, Four Different Quotes
Scope is the honest way to compare this work. Here are four routes, ordered by how much demolition each one carries behind it.
| Route | Does the Floor Open? | Best Fit |
|---|---|---|
| Acrylic or composite pan over the same footprint | Rarely | Sound subfloor and no layout change |
| Prefab base with panel or tile walls | Sometimes | Same footprint, a better finish |
| Custom tile shower on a new pan | Yes | Full tile, a bench, frameless glass |
| Conversion plus a layout change | Yes, and widely | Moving a toilet, a vanity or a wall |
Read those rows as tiers of disruption rather than tiers of taste. A route that never opens the floor is a short job with a small crew. A route that does is a longer one, with a plumber, a tile setter and an inspection between them.
Why the Drain Decides the Price
If your tub drains through a 1½-inch waste line, a shower can’t simply reuse it. The Illinois Plumbing Code is direct about it: shower receptacle waste outlets shall be at least 2 inches in diameter. Getting from 1½ inches to 2 means cutting the floor, reworking the trap and tying back into the branch line.
That one change drags a list of other work behind it. The subfloor gets patched. The waterproofing starts over. Sometimes a joist sits where the new trap needs to go, and the drain shifts a few inches, which changes where the pan has to slope.
It’s the same principle that separates a cosmetic bathroom update from a structural one. Sorting your list by which upgrades move plumbing and which don’t will tell you more about your investment than any tile sample can.
Older North Shore homes make this harder to predict. Floors that were leveled decades ago, cast iron lines and tight joist bays show up the day the tile comes off, so the drain answer can change once the floor is open. That is why a contractor’s price for an opened-floor route should say what happens if the conditions underneath differ from what anyone expected.
What a One-Day Conversion Actually Buys You
Bath to shower conversion companies that sell one-day systems build their pricing around never opening the floor. A molded acrylic or composite pan drops into the existing alcove, wall panels go up over the old surround, and the crew is out fast. It’s a legitimate product for a specific situation, and for plenty of bathrooms it’s the right buy.
It works best when the subfloor is sound, the drain already sits where you want it, and the goal is a safe, low-threshold shower rather than a design statement. A second bathroom nobody photographs. A rental between tenants. A parent who needs an easier entry now.
It works badly when the alcove isn’t square, as in some prewar homes, or when there’s any sign of old water damage under the tub. Panels bridge over a bad substrate instead of correcting it. You’ve bought a surface rather than a repair.
The trap is treating the two quotes as prices for the same thing. One is a system installed over what’s already there. The other is construction that replaces it. Line them up on what happens behind the wall and the gap stops reading like a discount. For a fuller look at the fast option, see whether a one-day bath remodel is worth the tradeoffs.
So ask one question before signing either kind of contract. What happens if the crew opens the wall and finds rot? A system installer may not be set up for that work, and knowing who handles it, at what price, is worth more than any promotional discount.
Waterproofing Is the Line You Never See
A tub is its own waterproof vessel. Pull it out and that protection leaves with it. What replaces it is a pan assembly, the part of a shower that does its work out of sight for as long as the shower is in use.
What the Hidden Layer Actually Costs You
Under the tile sits the waterproofing: a sloped mortar bed with a pan liner, or a bonded waterproof membrane, depending on the method. None of it shows once the job is done. All of it is why two quotes for the same-looking shower can sit far apart.
Low-priced conversions can save money here, and that’s the trade being made. A rushed pan doesn’t leak on day one. It weeps slowly into the joist bay, and you find it when the ceiling below starts to stain.
Ask each contractor which waterproofing method they use and whether they test the pan before the tile goes on. If you want a design for your own bathroom first, book a free design consultation and bring photos of the tub wall and the ceiling underneath it.
Glass, Tile, and Fixtures Move the Number Next
Once the wet work is settled, the visible choices take over. Tile is the biggest of them. A large-format porcelain wall with few grout lines sets faster than a mosaic floor with a linear drain, and the labor gap between those two can be wider than the material gap.
Glass is the second lever. A framed sliding door is the simpler answer, while frameless glass panels bring thicker glass, custom measuring after the tile is set, and a longer wait for delivery.
Fixtures look like the small decision, and they aren’t always. A rain head plus a hand shower can mean a larger valve and more hot water pulled at once. The EPA’s WaterSense program notes that standard showerheads use 2.5 gallons of water per minute, so running two heads together can outrun an older water heater. That’s a quiet line item people discover after the drywall is closed.
What’s Included, and What Shows Up as an Extra?
Before you compare two numbers, ask what each quote includes: demolition, the pan, wall surfaces, the valve and the drain work. Then ask what’s excluded. Glass, tile upgrades, niches, a bench, exhaust fan work and any drywall or paint outside the shower can land on either side of that line, and the exclusions are where quotes really diverge.
Two more items are worth pinning down in writing: who patches the ceiling below if the drain work opens it, and who is responsible for permitting and inspection. Both belong on the short list of questions worth asking a remodeling contractor before anything gets signed.
A bid that looks low can simply be a bid that’s narrow. Line the two up item by item and the gap explains itself.
Where the Design Comes In
A conversion goes better when the design questions are settled before anyone prices the construction. That is the part Kitchen Design Partners handles. We design the bathroom, from the layout and the vanity to the storage and the surfaces around them, and we supply the vanity cabinetry and countertops, plus tile if you buy it through us. Your contractor performs the conversion itself: the demolition, the drain and plumbing work, the waterproofing, the tile setting and the installation.
Because your designer works directly with your contractor, the drain question gets answered on paper rather than on demolition day, and the contractor prices a plan instead of a guess. In our Northbrook showroom on Dundee Road you can compare cabinetry finishes and countertop surfaces side by side, and your designer stays involved through the final walk-through.
When a Conversion Becomes a Full Bathroom Remodel
There’s a point where converting the tub stops being the whole project. If the vanity is dated, if the floor tile is going anyway, if the toilet sits somewhere awkward, doing those jobs separately can cost more than doing them together. The floor is already open. The trades are already scheduled.
That math is what pushes some homeowners toward a full bathroom remodel instead of a one-fixture swap. It isn’t always the right call. In a guest bathroom used twice a year, the simple insert wins on every measure that matters. If you’re still deciding whether the tub should go at all, start with when to convert a bathtub to a walk-in shower.
Frequently Asked Questions About Tub-to-Shower Conversion Costs
How Much Should a Tub-to-Shower Conversion Cost?
There isn’t one honest number, because the route decides the price. A pan set over the existing footprint is the lighter job; a tiled shower on a new pan, with the drain enlarged, is the heavier one. Your contractor prices it after seeing the bathroom, so compare quotes on the same scope, the same materials and the same exclusions.
How Much Does It Cost to Install a Walk-In Shower?
A walk-in shower built in an old tub alcove is priced like a conversion, because it is one. The price climbs when the opening widens, when a curb is removed for a flush entry, or when the drain has to move to make the entry work.
Can I Keep the Existing Drain Location to Save Money?
Sometimes, and it saves floor work. Keeping the trap where it is avoids the heaviest part of the job. The waste outlet still has to be sized correctly for a shower, so plan for drain work even when the location doesn’t change.
What Makes a Conversion Quote Jump the Most?
Opening the floor, then frameless glass, then tile labor. Anything that pushes the project past the original footprint, like widening the opening or moving a wall, resets the number rather than nudging it.
Does Kitchen Design Partners Do Tub-to-Shower Conversions?
We design the bathroom and supply the vanity cabinetry and countertops, plus tile if you buy it through us. Your contractor handles the conversion and installation, and we work directly with them. If you don’t have a contractor yet, we can introduce trades we know and trust.
Want a Plan for Your Own Bathroom?
A quote is only as good as the plan behind it. The figure that matters comes from looking at your tub wall, your drain and what sits under the floor, after the design decisions are made. That’s a conversation, not a guess, and it’s the fastest way to learn which of the four routes above your bathroom belongs in.
You can book a free design consultation with the Northbrook team, bring your photos and measurements, and leave with a clear direction your contractor can price.