You rip everything out in that picture and start over, because everything in that picture is the same old age decrepit. Valves are proprietary. You wouldn't leave old and decrepit behind the wall and spend 3K for shiny new doodads outside the wall. Replace it all. Including the tile and (incorrect) waterproofing. I can see the rot underneath from here.

I should add, we will replace the plumbing behind the tile as we know there’s a leak. We added a garage to the house so now we have access to plumbing we didn’t before.

You don’t think the tile is salvageable? Cleaned, maybe regrouted/sealed sure, but ripping it all out?

Luckily, you are able to access your plumbing through your garage wall!

The rough in valve inside the wall needs to match with the fixture that turns the shower on/off and controls temperature. As far as the other fixtures in the shower, you can install different brands of shower heads/hand held shower heads/etc. However, I don't know if valves are a common size that would fit the holes currently made in your tile.

I would have someone find out what is causing the leak. Once you know that, you'll be able to speak with someone at Ferguson's in order to configure your new system.

The leak is because none of that tile has proper waterproofing behind it. It is going to smell to high heaven when you tear it all out.

Gut and redo all. You can see there are major issues. https://www.ceramictilefoundation.org/homeowners-guide-to-hiring-qualified-tile-installer

Gut to the studs.

@alanalinette

To answer your question:

You don't need to buy or replace this as a "system". You can replace the rain head, handheld, body sprays, etc. individually - and from any manufacturer. Most are going to use standard 1/2" tapered threads. Your plumber knows this.

The mixing / control valve gets replaced as a unit - if you have to replace it. The problem with replacing is both access to the plumbing (which you say you have) and the size of the hole in tile. It may be easier to repair the mixing valve if you need to. It's generally possible to replace them if you aren't getting into an issue with the tile.

Higher quality mixing valves have a rough-in base so that you can replace the valve and exterior trim without replacing the part in the wall. So, for example, if you have a Delta valve, you can replace everything inside and outside the valve with another Delta kit without access to the back of the wall.

Now the part you didn't ask:

Where exactly is the leak coming from? You MUST identify the source of the leak first.

Evaluate the shower itself. Is it watertight? You can see the back side of this - is there evidence of leaking? If not, great - no need to demo. If the shower base is leaking it's a demo unless it's the drain connection (again, you need to understand what exactly is leaking).

If water is leaking around the holes in the tile around the mixing valve / body sprays that can probably be addressed without demo.

Demoing this to the studs is a MUCH bigger project because you will be getting into the floor - and possibly much of the bathroom. Unless you just have $50k burning a hole in your pocket, I'd sit tight.

Even if you did later have to do more work on the shower, the money that you are putting into replacing the shower heads (and possibly mixing valve) just isn't that much. The only part of your proposed project that could get a little more involved is if you have to completely replace the mixing / control valve if it doesn't have a rough-in base.

@alanalinette

Please post back and tell us specifically about the leak. Can you see that plumbing is leaking from the back side? Post photos of the back of this wall.

Thank you all for your helpful comments! I spoke to my husband, who knows more about the project than I do.

1. We are replacing all of the plumbing behind the wall no matter what. As I said before, now that we've added onto the house, we have access to plumbing that we did not have before.

2. To his knowledge, there is no leak behind the wall. The fixtures themselves leak (like between parts of the showerhead). Obviously, if there is any rot/damage we'll have to consider ripping it all out but not at this point.

3. I appreciate how Jake's post outlines exactly when/when we would need to gut/repair, and that replacing the fixtures now and ripping out everything later wouldn't be that much of a setback. That will have to be our plan, as we're still catching our breath from a huge garage/screen porch addition.