Rough-in valve vs. trim
A shower is two purchases. The rough-in valve is the brass body that gets plumbed inside the wall. The trim is everything you see: handle, escutcheon plate, showerhead, and tub spout. Trim only fits valves from the same manufacturer, and often only the same valve series, so check the trim’s compatibility list before the valve goes in. Swapping brands later means opening the wall.
Pressure-balance vs. thermostatic
Most plumbing codes require an anti-scald valve on showers and tub/showers. Both types below qualify; they just protect you differently.
- Pressure-balance valves react to a change in hot or cold pressure, like a toilet flushing, and hold the mix steady. One handle usually controls both volume and temperature. They’re the standard, affordable choice for most homes and rentals.
- Thermostatic valves hold a set temperature and usually separate volume from temperature control. They cost more and are common in higher-end builds and multi-outlet showers such as body sprays or a separate handshower.
Either way, set the valve’s high-temperature limit stop at install. It caps how far the handle turns toward hot.
Connections: PEX, sweat, or threaded
The valve body has to match how the house is plumbed. Look for it in the product title:
- PEX crimp (F1807) uses copper crimp rings and a crimp tool.
- PEX expansion (F1960) is the Uponor/Wirsbo style, with an expander tool and PEX-A tubing.
- Sweat (copper) is soldered. Remove the cartridge first so heat doesn’t damage it.
- IPS (threaded) uses standard pipe threads with adapters for any system.
Valves listed “with stops” have built-in shutoffs, so you can service the cartridge without shutting off water to the whole house. On rentals and multi-unit jobs they’re worth it.
Shower-only or tub/shower
A shower-only setup needs one outlet, up to the showerhead. A tub/shower valve has two, up to the head and down to the tub spout, and a diverter sends water to the head. The diverter is either in the tub spout (lift-gate spout) or in the valve trim. Buy the tub spout that matches the valve’s rough-in instructions, since spout connections (slip-on vs. threaded) aren’t interchangeable.
Setting depth at rough-in
Every valve has an allowable depth range from the face of the finished wall, including tile and backer board. Most ship with a plaster guard or test cap marked with that range. Mount the valve so the finished wall lands inside it, or the trim won’t seat. It’s the most common rough-in callback.