Tub to Shower Conversion in Valencia, CA

A tub and a shower look alike from the hallway, but the plumbing asks different things of each. Three parts change, and they are the reason this is more than a tile job.

The California Plumbing Code sizes a tub drain at 1 1/2 inches and a shower drain at 2 inches (Table 702.1). There is a useful exception for exactly this job: a conversion can keep the existing 1 1/2 inch trap as long as the new shower is no bigger than 36 by 60 inches. Go bigger and the drain line gets upsized, which on a slab means opening the floor.

The old tub valve with its spout comes out. The code calls for a pressure balance, thermostatic or combination valve on every shower, with the water capped at 120 degrees Fahrenheit at the outlet (section 408.4). It also asks that the handle sit where you can reach it and set the temperature before stepping into the spray (408.10), which is why the valve often moves toward the entry side of the alcove.

Where the tub sat, a shower floor gets built from scratch. Under the tile goes a waterproof liner that turns up at least 3 inches above the curb and slopes to the drain (408.8). Before any tile goes down, the pan is plugged and flooded 2 inches deep, and it has to hold that water for a full 15 minutes (408.8.5). That test happens at the rough inspection, so it is on the contractor's schedule, not yours.

A standard shower has a curb, a low wall across the front that keeps water in. The code sets it between 2 and 9 inches above the top of the drain, with the floor inside sloping at 1/8 to 1/2 inch per foot (408.6).

A curbless shower is allowed too, and it is the easiest to walk into, especially for anyone using a walker or expecting to live in the house for decades. The trade is that the code then treats the whole bathroom floor as a wet location, so the waterproofing runs further than the alcove. In a house on a slab, getting the shower floor low enough usually means cutting and lowering the concrete in the alcove.

Almost always. The state minimum for a shower is 1,024 square inches of floor with room for a 30 inch circle, kept clear up to 70 inches above the drain (408.7). A 30 by 60 inch shower base is named as meeting the rule on its own, which covers the usual Valencia tub alcove.

The glass has its own rule. Any glass in a shower or tub enclosure, or within 60 inches of one with its bottom edge under 60 inches off the floor, has to be safety glazing under the California Residential Code (R324.4.5 in the 2025 edition). The contractor orders the door and panels as safety glass, and a window inside the alcove may need replacing.

Santa Clarita adopted the 2025 California codes for permit applications from January 1, 2026. Its own list of work that skips a permit covers finish work and like for like fixture swaps, and a tub to shower conversion is neither, because the drain and the valve change. Building and Safety reviews small residential jobs like this at the counter, then an inspector sees the plumbing and the pan before the walls close and comes back for a final.

One more thing rides along on houses built on or before January 1, 1994. Before the city signs off on the permit, California Civil Code 1101.4 has every older high flow toilet, showerhead and faucet in the house swapped for a water saving one. A home that already has newer fixtures has nothing to do.

No neutral source publishes a price for this job, in Valencia or anywhere else. What does exist is a whole room figure. Reading the 2023 American Housing Survey, Harvard's housing center found owners who hired out a bathroom remodel spent $12,285 on average nationwide (Improving America's Housing 2025). That average covers whole rooms, so read it as scale, not as a price for a conversion.

The spread is wide because the job is. The low end is a one piece acrylic shower base and wall kit dropped into the old alcove. The high end is a tiled shower with a new pan, glass and a bench. Moving the drain, going curbless or upsizing past 36 by 60 inches pushes toward the top. The bathroom remodel cost guide covers what moves the price across the whole room.

If this is the last tub in the house, think about who uses it. Small children are far easier to bathe in a tub. When the house has a second tub, keeping that one and converting the hall bath is the usual middle ground.

Longer than the tile work alone. The pan has to be built and water tested, the rough inspection has to pass before the walls close, and the glass is usually measured after the tile is finished and then made to fit. The contractor puts the dates in writing with the price.