Tub/Shower Convert from 3 handle to one

[scri8e]

This is a 10 unit apartment building.
5 units up 5 units down.
I have a turn over in #5 meaning the past tenant has moved out so I am doing some upgrades in between renters. This building was built in 1965. I am in Long Beach CA. The bathroom has a tub/shower combo with 3 handles. Hot and cold and tub to shower diverter. I am re-building the tub/shower surround as there is a window in the
tub/shower wall that has leaked. I found not only dry rot damage to the joists, but wetness inside of the wall around the window, additionally termites.

So I have ripped the walls all the way around the tub surround. While I'm into it this deep I figure I might as well change the 3 handle valve/faucets etc to a one handle moen config.
So I don't have the ole tenant cranks the water off too tight and ends the valve life short lived saga.

While I'm in the middle of this exploration and wall rip. The upstairs tenant in #10 takes a shower. No big deal. EXCEPT.... drain water starts coming out the over flow in #5 where I am working and also is coming out from under the tub where I am working. So I clean up the mess. Tell the upstairs tenant I have a problem with downstairs bathroom. Please hold off on showers/baths until I get it fixed. Hope to have it fixed by tomorrow will let you know.

I take off the over flow plate and the darn pipe that was I guess sorta attached to it falls off.

So my question/s are.... What do I need to change in the wall so far as to switch over from a 3 handle to a one handle. Because I think I can get at everything I need to by pulling the existing valve assembly to replace with the 1 handle valve assembly. Meaning get at the tub drain and the overflow pipes and such.

I do have an access panel on the outside wall of the building. Can't see much though. There is not a bathroom back to back in #4 just their bedroom wall. So only #10 upstairs is connected with #5's bathroom plumbing. I can go through the wall in #4's bedroom to get at the plumbing if I need to. Or I can pull the tub if that is what is needed?
Now is the time to do it once do it right.

Does anyone have/know of a diagram of the
plumbing for this switch over from a 3 to 1?

Thanks for you input.

[Verdeboy]

You forgot to mention that you only have 3 days to do all this and have to run work orders all day, as well as clean up the grounds!

I worked in apartment maint. for years, so I know the stress it causes.

With all due respect, I'd focus on the dry-rot, the leaky window, the termites, and the drain problems, before even thinking about upgrading the shower manifold, which is basically for aesthetic reasons.

[scri8e]

Ah yup you know the drill. LOL.

I'm trying to be logical. I figure since I want to change over to 1 handle any way. Changing that now would give me the room for access I need to handle the drain water from the bathroom above coming in under the tub and flooding the apartment I'm working in. That takes domaince over the walls and dry rot etc. Got to get the plumbing done right and first before I do the restructing of the walls and the wall buttoning up. Finishing out with Tile walls and tiled around the window.

[jadnashua]

3-handle to one isn't that big a deal. Still has hot and cold coming in, then a tub spout with divertor for the shower head. If the piping is galvanized, replace with copper while you have the walls open.

If the window is wood, consider changing it to a vinyl unit. You'll never keep the wood one from degrading - you have a a chance with a vinyl one. You need to make sure the sill is sloped into the shower and the waterproofing is impeccable.

For tiling help, check out www.johnbridge.com