Remodeling a Bathtub to a Shower: Planning Steps

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Remodeling bathtub to shower work is usually more than swapping the tub for a shower base. The plumbing, the drain location, the subfloor, and the waterproofing decide how big the job is, and those parts are often hidden until the tub comes out. The three sources below all describe that scope. Two of them are from companies that sell related products, and one is from a contractor-matching site, so the advice is useful but not neutral. This guide walks through the planning decisions and the stages the sources describe, and it recommends a licensed plumber or contractor for the plumbing, the subfloor, and any structural work.

Quick answer

Plan the plumbing first. Aquatica says that if you want a different showerhead height or location, you may need to reconfigure the plumbing.
Expect the drain to be the biggest variable. Block Renovation says a tub drain and a shower drain are not interchangeable, and moving a drain “is rarely simple.”
Check the subfloor and framing once the tub is out. LX Hausys says the subfloor should be “both level and stable,” and Block Renovation describes rot and water damage that hide behind old showers.
Waterproof the walls behind the new surround. Aquatica says to use waterproof membranes behind tile and to seal seams with silicone caulk.
Check permits with your local building authority before demolition. LX Hausys says to reach out to the local building authority for plumbing, electrical, and structural work.
Shut off the water and bring in a licensed plumber or contractor for the plumbing, the subfloor, and any structural change.

How we chose these sources

Three independent publishers were used. Aquatica is a bathtub maker and seller that publishes a home upgrade guide. LX Hausys is a surfaces company whose blog post covers the conversion. Block Renovation is a contractor-matching and renovation planning site. Each source names its publisher, and each covers the whole conversion, not just one product. Because two of them sell related products, the guidance below is checked against the others wherever possible, and the text says when only one source makes a point.

Several other pages returned blocked or error responses. Those pages were not counted. None of the three sources is a government or standards body, so the guidance is trade practice, not code.

Decide the layout before demolition

The layout decision comes first, because it sets how much plumbing and floor work follows. Aquatica describes two basic shower-base types. A curbed base is easier to install and is common in kits, while a curbless base sits flush with the floor and needs subfloor leveling. Aquatica notes that “curbless designs offer superior accessibility but may require subfloor modifications.” Block Renovation says a curbless or wet-room shower may need the floor rebuilt and re-sloped.

Block Renovation also makes the space point directly. A shower that already fits the tub footprint is a much simpler job than a stall that needs its walls moved. Block Renovation says that moving a wall, or taking space from an adjacent closet, usually comes with a layout change. The source adds that a corner shower footprint can sometimes take a corner tub instead, which can solve the space problem without moving walls. That point is from one source only.

Measure the existing tub and the wall framing, then plan the finished dimensions. Block Renovation advises measuring to the finished surface, not the framing, because backer board, waterproofing, and tile take up space. Plan the shower and the drain on paper before the tub comes out.

Permits and code

Aquatica says that many cities require permits for bathroom remodels, “especially if plumbing is being modified.” LX Hausys says the permitting step is to reach out to the local building authority to identify which permits are needed, “particularly for plumbing, electrical, and structural modifications.” The permit process may include detailed drawings and fees, according to LX Hausys. Those details differ by city, so check locally before you start.

Aquatica also lists code points that the inspection will check. Drain sizing and venting must be up to code, all new plumbing should be permitted and inspected, and any electrical work such as lighting or outlets should be GFCI protected. Aquatica advises checking with the municipality or hiring a licensed contractor who knows the local building codes.

Shut off the water and disconnect the tub

LX Hausys says to shut off the water supply to the home before starting. It then says to drain the residual water from the plumbing by opening all faucets and flushing the toilets, so that nothing leaks or floods during the work. LX Hausys adds that buckets or towels help catch water that escapes from the pipes.

Aquatica’s removal order starts with disconnecting the plumbing, including the drain and overflow, and removing the surrounding tiles or panels to reach the fasteners. LX Hausys describes removing the tile, cutting out wall sections around the tub, detaching the spout, faucet, and drain, then lifting out the tub. Each source describes a slightly different order, so follow the one that matches your tub, and stop if you find a condition you did not expect.

The tub itself should be removed with care. LX Hausys describes unscrewing or prying out the fasteners that hold the tub to the wall, and cutting the caulk that seals it to the floor. Aquatica says to be cautious with drywall or plaster to avoid damaging studs.

What hides behind the walls

Demolition is where the scope changes. Block Renovation says demolition can uncover “mold, rot, or failed waterproofing” that has to be repaired first. It lists the usual findings: mold behind the surround or inside the wall cavity, a rotted subfloor under the old shower pan, failed waterproofing, slow leaks at the supply lines or the old drain, and framing weakened by long-term moisture.

LX Hausys says to look for telltale signs of water damage, including rot or mold, and to repair them before moving on. Aquatica says to replace any rotted or mold-damaged studs or drywall. Those are the steps to take when the wall is open, and they are the reason to plan time and money for surprises. Block Renovation recommends setting aside a share of the budget for conditions found once the walls are open.

Good lighting and ventilation are part of the plan too. LX Hausys says they are imperative to fend off mold and mildew. A new shower in a poorly ventilated bathroom can create the same problem again.

Drain relocation and plumbing

The drain is where most conversions get harder. Block Renovation explains that a shower drain usually sits in the center of the pan and ties into a trap sized for a shower, while a tub drain sits near one end. A tub also has an overflow drain, which most showers do not have, and the trap may need to move to match the tub’s drain. Block Renovation notes that “moving a drain even a foot or two is rarely simple.”

The construction type changes the work. Block Renovation says that on a wood-framed floor, a plumber can often work from below or open the subfloor to reroute the drain. On a concrete slab, relocating a drain can mean cutting and patching the slab, which adds time and effort. Aquatica describes reconfiguring the plumbing when you want a different showerhead height or location. Plan the shower valve and head position on the same drawing as the drain.

Aquatica describes installing the shower valve and testing the water pressure before closing up the walls. Do that test before any wall covering goes on, because a leak found later is harder to reach.

Subfloor and framing

The floor under a new shower has to carry the weight and drain correctly. Block Renovation says the added weight can mean checking or reinforcing the floor structure, especially on an upper level. LX Hausys says the subfloor should be both level and stable to give a reliable base for the new shower, and it recommends examining and repairing the subfloor before building.

Check for rot and softness by pressing on the subfloor and framing with a tool, once the tub and any tile are gone. Block Renovation lists a rotted subfloor under the old shower pan as a common finding. If the subfloor is soft, or the framing is wet, stop and call a licensed contractor before covering it.

Waterproofing and the walls

Aquatica describes installing cement board on the walls before tile, and says that board must be waterproofed. It recommends using waterproof membranes behind tile and sealing corners with silicone caulk rather than grout. It also says to waterproof all seams and joints. Block Renovation describes waterproofing as the membrane, backer board, and sealing that keep water out of the framing behind the new tub. Those points agree, and both describe the same layers.

Aquatica also says to avoid materials that are difficult to maintain or prone to cracking, and to choose non-slip flooring and materials rated for wet areas. Those are general material points, and the sources do not give product names as a recommendation in this guide.

For the tub spout and diverter that often comes off during the work, see how to install a bathtub diverter spout. For cleaning the tub and the surround once the job is done, see how to clean a bathtub.

Do-it-yourself or hire a professional

LX Hausys says that undertaking DIY plumbing “can void many home insurance policies, so it might be safer to leave this task to professionals.” That is a claim from one source. It is worth checking your policy before doing any plumbing yourself. LX Hausys also says professionals bring specialized knowledge and often come with warranties.

Block Renovation describes the labor as often the largest share of the work, because a conversion touches demolition, plumbing, framing, waterproofing, and finish trades. Aquatica says the conversion can be managed as a DIY project or with a contractor. Those views differ. The safe reading is that the plumbing, the drain, the subfloor, and any structural change should go to a licensed professional, and that cosmetic work can be done by a capable homeowner if the rest is complete and inspected.

When you hire a contractor, ask how the drain will be moved, how the subfloor will be checked, what waterproofing is planned, and whether the plumbing will be permitted and inspected. Those are the points the sources focus on.

What we could not verify: what the sources do not say

None of the three sources gives a specific slope for a shower floor, a drain size, or a vent size. The local code sets those numbers, and no source opened gives the code figures.
No source gives a permit rule for a particular city or state. Each one says to check locally.
The sources do not describe a specific shower base or pan product for an existing tub opening.
No government, extension, or standards source was opened. The advice is from a tub maker, a surfaces company, and a contractor-matching site.
Only one source describes using a corner tub in a corner shower footprint. The other two sources do not cover it.
No source says how long a converted shower will last, or how often its waterproofing should be checked.
The sources do not say how to handle a slab drain that is cracked or undersized in an existing home.

FAQ

Does converting a tub to a shower always require moving the drain?

Not always. Block Renovation says a basic conversion can keep the drain in place if the shower sits in the same footprint, while a new layout or a shower drain in a different spot usually requires moving it. The sources do not say what fraction of projects need a move.

Do I need a permit?

Aquatica says many cities require permits for bathroom remodels, especially when plumbing is changed. LX Hausys says to contact the local building authority. Check with your city before demolition.

What should I check first when the tub comes out?

Look for mold, rot, and signs of water damage in the wall cavity and the subfloor, as Block Renovation and LX Hausys describe. Replace rotted or mold-damaged studs or drywall, as Aquatica says, and stop for a contractor if the subfloor is soft.

Can I keep the old drain?

The sources say a shower drain sits in the middle of the pan, while a tub drain sits at one end and has an overflow. If the drain position stays the same and the trap fits the new shower, the move may be avoided, but the sources do not say that for any specific tub or shower. A plumber should confirm it.

How do I keep water out of the wall?

Use waterproof backer board or membranes behind tile, seal seams and corners with silicone, and test the shower valve and plumbing before closing the walls. Aquatica and Block Renovation both describe these layers.

Is this a DIY job?

The sources differ. Aquatica describes the work as something experienced DIYers can take on, while LX Hausys says DIY plumbing can affect home insurance and should go to professionals. For the plumbing, drain, subfloor, and structure, use a licensed plumber or contractor.

Bottom line

A bathtub-to-shower remodel is a plumbing and waterproofing job with a tile finish, not just a new surround. Decide the layout first, check the drain and the permits, shut off the water, open the walls, and fix any water damage before the new surround goes in. Use a licensed plumber or contractor for the plumbing, the subfloor, and any structural change.

Sources

Aquatica Baths USA, “Changing a Bathtub to a Walk-In Shower: Home Upgrade Guide.” https://aquaticausa.com/blogs/aquatica/changing-a-bathtub-to-a-walk-in-shower (opened 2026-10-27)
LX Hausys, blog post on converting a bathtub to a walk-in shower. https://www.lxhausys.com/us/blog/wp-json/wp/v2/posts/3840 (opened 2026-10-27)
Block Renovation, “Shower-to-Tub Conversion: What It Really Costs and How to Plan One.” https://www.blockrenovation.com/guides/shower-to-tub-conversion-cost-and-planning-guide (opened 2026-10-27)