Access to tub faucet - size of hole in drywall?

[AcidWater]

How big a hole do I need to cut behind the tub faucet to replace it? Want plenty of working room.

The valves are 24" above the floor, the spout about 19". 3 valve type with 8" spacing.

the big question is: How much above & below that should I allow to get to the unions, if present? I want to cut a single piece of drywall out so I can replace it easily.

Its in a closet so I can go large... stud indicator says there's a stud in the middle.

[MACPLUMB 777]

Go stud to stud on the two outside studs that always does it for me

[hj]

Getting to the unions is not the problem because they are right below the hot and cold stems. Piping to the new valve is where you may have problems. If you go below the tub spout, 6" above the hot and cold handles, and stud to stud, you should be fine.

[AcidWater]

Okey Dokey. Hopefully the replacement will fit the existing unions.

[johnjh2o1]

Okey Dokey. Hopefully the replacement will fit the existing unions.

That's not going to happen. Most new three valves, if you can find one no longer have unions. Even if they did they wouldn't fit the old ones.

John

[hj]

They MIGHT fit if the new faucet is the same make as the old one, but even then they sometimes change the patterns to make them "lighter", (i.e., cheaper).

[AcidWater]

How do union joints differ? Are they brand proprietary?

Gotta cut the hole in the wall today...