Do I Need a Permit to Convert a Bathtub to a Walk-In Shower? in Verenigde Staten
Converting a bathtub to a walk-in (curbless or low-threshold) shower is one of the most popular aging-in-place and bathroom modernization projects. In most jurisdictions, it requires a plumbing permit because the conversion involves relocating or resizing the drain from a bathtub drain (typically 1.5-inch with an overflow) to a shower drain (2-inch minimum per code, often with a linear drain body), modifying the water supply rough-in for a new valve position, and changing the waterproofing membrane (the shower pan liner or sheet membrane system must meet code requirements that differ from a bathtub surround). An electrical permit is also required if the project adds or relocates a GFCI-protected outlet, exhaust fan, or recessed lighting in the wet area. The conversion frequently involves structural work — cutting into the subfloor to reposition the drain, adding blocking for grab bars, or modifying the curb — which triggers a building permit in addition to the plumbing permit.
Do you need a permit?
Usually yes
- Permitting authority
- Local Building / Plumbing Permits Office
- Typical fee
- $100–$500
What triggers a permit
- Relocating or resizing the drain from a 1.5-inch bathtub drain to a 2-inch shower drain
- Modifying the water supply rough-in (moving valve body, adding a thermostatic mixing valve or diverter)
- Cutting into the subfloor or floor joists to reroute the drain line to a new position
- Installing a new shower waterproofing system (pan liner, sheet membrane, or liquid-applied membrane)
Country-specific detail
In the US, converting a tub to a walk-in shower requires a plumbing permit because the drain size must change from 1.5 inches (standard tub drain per IRC P3005.4.2) to 2 inches (minimum shower drain per IRC P3005.4.2), and the trap must be accessible. The shower receptor or finished floor must slope uniformly to the drain at ¼ inch per foot (IRC P2709.1), and the waterproofing membrane must extend at least 3 inches above the finished threshold height on all sides. For a curbless (zero-threshold) shower, the entire bathroom floor may need to be re-graded, which typically requires removing the existing subfloor — this triggers a building permit for structural work in addition to the plumbing permit. GFCI protection is required for any receptacle within 6 feet of the shower (NEC 210.8), and the exhaust fan must provide at least 50 CFM (IRC M1507.4). If the bathroom has only one bathtub and no other tub in the house, some jurisdictions flag the removal during plan review — while no IRC provision requires a bathtub, appraisers may note its absence as a functional deficiency in homes with multiple bedrooms.