Tub-to-Shower Conversion in Florida.

What You Are Rebuilding

A tub-to-shower conversion replaces a bathtub with a walk-in shower in the same footprint, but the value is in what gets rebuilt behind the tile, not the fixture that gets carried out. A bathtub is a single waterproof vessel; a shower is an assembly of separate parts — substrate, membrane, sloped pan, drain, and tile — that has to stay watertight at every joint. In Florida, where the wall cavity rarely dries out between humid days, a weak point in that assembly is where mold starts.

Removing the tub exposes three systems that almost always need work: the waterproofing membrane across the new wet walls and floor, the shower pan that must be sloped to drain, and the drain line itself, which a tub and a shower do not share. Treating the project as a fixture swap — new pan over old plumbing, tile over old backer — is the single most common reason a converted Florida shower leaks inside the wall within a year or two.

The visible finish is the easy 20 percent. The hidden 80 percent is the membrane and the drain, and it is the part that decides whether the shower lasts. That is why a conversion is priced and scheduled as a small bathroom rebuild rather than an afternoon fixture change, and why the order of operations below matters as much as the materials.

The Waterproofing Assembly

Waterproofing is the heart of the conversion. The tile and grout you see are not the waterproof layer — water passes through grout joints over time, so a continuous barrier has to sit behind and beneath the tile. That barrier is a bonded waterproof membrane, and in a Florida shower it is the difference between a dry wall cavity and a hidden mold colony.

The governing standard is ANSI A118.10, the specification for load-bearing, bonded, waterproof membranes for thin-set ceramic tile and dimension stone. A membrane that meets it has passed a hydrostatic test in which a 24-inch column of water is held against the surface and the back is checked for any moisture that gets through. Sheet membranes and liquid-applied (paint-on) membranes both qualify when installed to the manufacturer's detail, with seams, corners, and the drain flange sealed into the system.

Where it goes

Across the full shower floor, up every wet wall to above the showerhead, and lapped into the curb or, for a zero-threshold build, into the surrounding floor. The membrane is continuous — a gap at a seam or a corner is a leak path.

Why it matters more in Florida

High indoor relative humidity means the wall cavity stays damp, so any moisture that breaches a failed barrier does not dry — it feeds mold on the framing and backer. A membrane that would limp along in a dry climate fails fast here.

What it bonds to

A proper backer — cement board or a foam tile-backer panel — never paper-faced drywall, which is organic food for mold. The membrane and backer are a system, specified together.

The detail that fails most often is the transition between the wall membrane and the pan, and the seal at the drain flange. Those are the joints water finds. A correct assembly treats the membrane as one unbroken envelope from the walls into the pan and bonded tight to the drain — the same principle covered in depth in our shower tile waterproofing breakdown.

Slope and the Drain

Water only leaves a shower if the floor sends it to the drain and the drain can carry it. Two code numbers govern this, and a conversion almost always has to change the drain to meet the second. Slope first, then the pipe.

Under IRC P2709 and IPC 417.5.2, the shower pan liner must be pitched 1/4 inch per foot — a 2 percent slope — toward the drain from every direction, and the finished shower floor must not exceed 1/2 inch per foot, which would become a slip hazard. That slope is built into the mortar bed under the membrane, not faked with tile, so the water plane beneath the surface drains even if a grout joint lets moisture through.

The drain itself is the part homeowners do not expect. A bathtub typically drains through a 1-1/2 inch trap, but a shower waste outlet must be 2 inches in diameter under IPC 417.5. So the conversion means opening the floor, relocating the drain from the old tub waste to the center (or chosen point) of the new pan, upsizing the line, and re-setting the P-trap with a code-compliant vent. On a Florida slab-on-grade home that can mean cutting and patching the slab — real work, and a real reason the project is not a swap.

The Conversion, Step by Step

The sequence is fixed because each layer protects the one above it. Done in order, a Florida conversion runs a few days of focused work; done out of order, it traps a defect behind finished tile.

The flood test in Step 6 is the one a homeowner should insist on watching. A pan that holds standing water overnight has proven its waterproofing before it is sealed under tile — the only honest way to know the membrane works, and cheap insurance against opening a finished Florida wall later.

Accessibility and Grab Bars

The strongest case for converting is accessibility, and Florida's large share of aging-in-place homeowners makes it a leading reason people lose the tub. A curbless or low-threshold walk-in shower removes the high tub wall that is the most dangerous step in any bathroom — but only if the safety hardware is anchored into structure, not screwed into tile.

Under ICC A117.1, a grab bar and its fasteners and supporting structure must withstand a 250 lbf (1112 N) load applied in any direction. The code does not strictly mandate blocking, but a drywall or tile fastener cannot meet that load on its own, so in practice the wall has to be reinforced — solid blocking framed between the studs during the rebuild. Add it everywhere a bar or fold-down bench could plausibly go, because retrofitting blocking later means opening a finished, waterproofed wall.

The same logic favors a low or zero threshold and a hand-held showerhead, both easiest to build while the walls are open. A true curbless build is its own discipline on a Florida slab — the floor has to be recessed or built up so the slope still contains the water without a curb — which we cover in the curbless walk-in shower guide. For most conversions, a low-curb walk-in installed by our walk-in shower crew hits the accessibility goal without recutting the slab.

The Keep-One-Tub Resale Rule

Converting every tub in the house can cost resale value, so the working rule among agents and remodelers is simple: keep at least one bathtub in the home. Families with young children look for a tub, and a house with none narrows its buyer pool. The fix is to choose which bath to convert, not whether to convert at all.

In a two-or-more-bath Florida home, convert the bath you use daily — usually the primary — for the walk-in shower you want, and leave a tub in a secondary or guest bath to satisfy the resale checkbox. In a one-bath home, the calculus is different: a single bathroom with no tub is a real resale liability, and many homeowners there choose a tub-shower combination or a deep walk-in with a removable bench rather than eliminating the tub entirely.

The decision sequence is the same in every case: pick the right bath, build the waterproofing and drain correctly, and frame in the accessibility blocking while the walls are open. When the conversion is one move inside a larger project, the complete Florida bathroom remodeling guide ties the tub decision to ventilation, code, and the rest of the room — and our conversion crew handles the demo-to-tile sequence across Florida.