What is a Rough in Valve? Types and Functions Explained 

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Sudden water fluctuations don't stand a chance when the shower system's heart works with precision in controlling the water volume and temperature. A shower system heart? This is what you need to know...

What is a rough in valve

If you find yourself wanting to learn about shower valves, then you’re well on your way to becoming a true hands-on home handyman.

Why is that?

Well, in a shower setting, there are exposed shower valves and those hidden inside your shower wall. Knowing how these things behave – especially those that are installed inside your wall – will definitely give you a big advantage.

For one…

…knowing more about the make-up of your bathroom could save you some cash in the long haul. And it won’t be quite so frustrating anymore when something goes wrong with your water temperature or pressure.

So enough of this; let’s not keep you waiting. Let’s take a look at some of the shower valve types that could make life easier for you and your morning showers a treat. 

Today, we’re going to look deeper into rough-in valves and thermostatic valves, among many others!

But wait rough-in valves? What is a rough in valve for a shower?

Rough in valve for a shower

Rough in valves are the valves that we don’t often hear or talk about unless you have some extra plumbing knowledge.

And no wonder…

…because this hot and cold water valve is hidden from view, being positioned inside your shower wall. But that doesn’t make it less important.

Actually, without this valve, you might just get surprised by sudden waves of scaldingly hot water at random times. If not, you might find yourself standing in the shower and shaking from the icy water.

Suffice to say…

…a rough-in shower valve is the very center of your shower system. To put it simply, it controls the temperature as well as your shower head’s water pressure.

It works in a way that it combines hot and cold water and then delivers it to the water outlets through the pipes where the water is mixed according to the ratio needed to achieve your preferred temperature.

Just remember that you can’t just grab a random rough-in valve and install it. There’s a right valve for every shower faucet and system. So be sure to do your assignment and research first. 

How Do I Choose a Rough-in Valve for my Shower

How to choose a shower rough in valve

Choosing a rough-in valve for your shower system is crucial as it will make the most difference in your showering experience. In fact, there are quite a few things you must consider before finally settling in on one model. 

The first factor is your pipes.

Rough-in valves aren’t one-size-fits-all hardware. Some shower valve types only fit particular pipe materials. 

That’s why you have to determine the material of your pipe first. PVC? Copper? Galvanized? Ask your plumber or your local hardware store first if the rough-in valve you’re eyeing is compatible with your pipes.

Your shower head matters, too…

…because, just like with your pipes, there are certain heads that aren’t compatible with some rough-in valves. 

As a matter of fact, some of them even work with fixtures of the same brand. So if you can, do your best to work with one brand only. 

But what if you can’t?

There’s a chance of compatibility issues, but it’s not always the case. You can still work around it successfully with the right combination and product quality. 

Although not strictly a must, you can also match your shower trim kit with your shower valve. The point here is to find out first if your fittings (or those that you’re planning to get) are going to work around your rough-in shower valve.

What Is a rough in and trim kit for a shower?

Shower Rough in Trim Kit

As mentioned earlier, a rough-in valve is a valve installed “in the rough” and is located inside your shower wall.

It’s the very heart of your shower system and controls the temperature and even pressure of your water, most of the time including your sink, tub, and bathroom water.

But that’s not all there is to it.

There’s also what we call the trim kit. You might have also heard it from your local hardware shop or your plumber.

Basically, shower trim kits consist of the visible components of your shower system. This includes the showerhead, the handles, faucet, spout, and many more. 

Shower trim kits are mostly decorative pieces, too, and they’re installed over the rough-in valve. That’s why it’s almost always better to get them from the same brand. But if you can’t, there are also brands that go well together.

Shower and Bathtub Rough-In Dimensions

Shower rough in dimensions

Some elements are forgivable for the shower rough in dimensions, such as the shower head, shower valves, and other shower fixtures that come with the trim set. 

Aside from that, the rough-in details are all about the placement as well as the size of the hardware like pipes.’

If you’re working with a tub and shower combination…

…the faucet is usually installed lower at around 12 to 18 inches above the tub’s rim. But if it’s only a shower stall, the faucet should be higher at around 48 inches from the floor. 

As for the shower head

…it’s even higher at around 72 to 80 inches from the shower floor, but it can also be adjusted according to the homeowner’s needs or preference. 

The vertical shower supply would then be placed 80 inches above the floor, around where the shower arm is placed. 

Going back to the bathtub unit…

…the faucet should be 20 to 22 inches from the floor, 4 inches to its sides (both left and right), and another 4 inches above the rim of the bathtub.

Typically, the drain is placed on the centerline, with its drain access having 10 to 14 inches of distance from the framing.

As for the sides…

…it should have at least 18 inches to the sides as well as the front side for comfort and functionality.

What is a pressure balance valve?

What is a pressure balance valve

Have you ever experienced enjoying a relaxing shower when all of a sudden, your shower head blasted scalding hot water without any warning?

Or perhaps it’s the opposite. Your relaxing shower was disrupted by the water being replaced from soothing warm to icy cold.

That’s simply because of the change of water flow within your pipes, and it happens whenever someone on the other side of the house turns another water fixture on.

And that’s what regulating valves are.

One of these water regulating valves is the pressure balance shower valve, which is made to avoid unwanted scenarios such as the ones mentioned above.

A pressure balance shower valve doesn’t sense temperature in order to control it. Rather, it detects the ratio of both hot and cold water so that it can adjust it according to your preferred temperature. 

So whenever you twist the handle…

…you’re indeed controlling both the water pressure and temperature. 

Basically, pressure balance valves work in a way that whenever it senses a drop in the water flow of one of the incoming water supplies, it will then adjust with its balancing diaphragm or spool to adjust it and match the water pressure in the hot and cold water supply.

As a result, your outgoing water in the shower won’t be too cold or too hot even if someone flushes the toilet or uses water for the dishwasher.

That being said, one of its cons is it doesn’t necessarily control the water pressure on different water outlets. So the water flow may change, but the temperature will still remain stable and constant.

You may have already noticed it in shower systems that have more than one showerhead. 

That’s also one of the reasons why it’s one of the most affordable waters regulating valves today. 

What is a thermostatic valve?

What is a thermostatic valve

While a pressure balance shower valve relies on water pressure to control water temperature, a thermostatic shower valve senses the temperature itself and adjusts it without affecting the pressure.

Generally, thermostatic shower valves have two controls – one for water temperature and one for water pressure or volume. 

So how does it work?

In comparison to the simple design of pressure balance shower valves, thermostatic shower valves are much more sophisticated. As a matter of fact, it has a sensor inside (usually a wax element) that detects the temperature and expands and contracts with the heat.

With this, the water flow for hot and cold water inlets is controlled, thus controlling the temperature too.

This system has lots of advantages. One of them is the consistency of the water temperature, whatever the water pressure is.

It could be a trickle or a strong flow, and the temperature will stay the same. 

That also makes the thermostatic shower valve a good valve if you want to conserve more water!

In addition to that…

…you’ll never get caught off guard with scaldingly hot water again because its valve is limited just to keep this from happening.

That being said, other people at home can also use and enjoy hot or cold water as much as they want.

And that’s not all.

A thermostatic shower valve also lets you preset the water temperature so that it’s ready to use for the next day, and you won’t have to adjust again or, worse, get startled by the water that’s too cold or too hot at the first turn of the knob.

What is the difference between a thermostatic shower and an electric shower?

Thermostatic VS Electric Shower

Many homeowners today seem to be confusing electric showers with thermostatic showers. But there’s actually a huge difference between the two.

First off, thermostatic shower valves work with a temperature sensor to detect the current temperature in order to adjust it according to your liking. It works with an element that contracts and expands as a reaction to heat, thus controlling how much hot or cold water gets mixed.

On the other hand…

…an electric shower is simpler but practical. It works with electricity to heat up your water and control the temperature according to your liking. 

Suffice to say, it has its own heating element and doesn’t need two water supplies. It can even work with a cold water supply only as it can independently heat the water up.

As a result, other people at home can enjoy warm water while you’re also using it in the shower!

It’s fairly easy to recognize an electric shower. It has an on and off switch that’s either cords or a flipping switch.

How does a thermostatic shower work?

How does a thermostatic shower work

Thanks to its intuitive and reliable design, a thermostatic shower works in a way that it collects water from both the hot and cold supply and then mixes them according to your desired temperature.

Its element senses temperature and expands and contracts according to it to limit cold or hot water whenever one of them runs in excess and affects the set temperature.

Aside from that…

…it also automatically shuts down whenever your cold water supply fails so as to avoid any scalding incident. Because of this, thermostatic shower valves are deemed one of the most family- and children-friendly shower valves there are. 

What are the types of thermostatic shower valves?

You might not know this, but there are actually different types of thermostatic shower valves to suit your particular needs.

Typos of thermostatic shower valves

1. Concealed Valve

A concealed thermostatic shower valve is for you who are looking for a minimalist look. 

As the name suggests, the valve itself is hidden behind a metal plate that you can install on your shower wall or even inside the wall. As a result, only the showerhead and handles are visible.

This creates a very clean and neat space and aesthetic that’s far from complex and cluttered. 

2. Exposed Valve

Now, if you want complete control of your shower experience, the exposed valve is for you. 

With the exposed valve, all shower workings and controls are sitting on the wall and might even dominate the entirety of it. But then, you’ll have complete freedom to switch between the water outlets that you have. 

Just make sure to get a well-designed, sophisticated trim kit as it could look too cluttered or complicated if not done right.

3. Bar Valve

Bar valves are one of the most affordable types of thermostatic shower valves and are also the best choice for compact spaces.

Its space-friendly design and simplicity are a favorite among humble homes and bathrooms. And it doesn’t hurt that it also comes in many different finishes and materials such as chrome and matte. 

4. Traditional Valve

A traditional valve is what happens when you combine the bar valve and the exposed valve.

In short…

…it’s a combination of modernity and vintage design. A traditional valve often has cross handles and lever, all in a metal plate installed on the wall.

How to fit a thermostatic shower?

Thermostatic Shower Valve Fit

Given that you now have a mixer and pipes for your shower, the first thing you need to do is to take the water supply from the drain with your pipes. And after that is when you’d get down and dirty on work.

  • You need to determine where you’ll get hot and cold water from. The easiest way to do this is to trace your pipes with the nearest cold and hot water taps as the starting point. Turn the water on and feel the pipes. The hot water pipe should feel warmer. 
  • Now, if you’re installing it above your bath, just tee into the tap supplies. On the other hand, tee into the closest water pipes if you’re working with a shower stall. 
  • You may get down to work once you’ve determined where the hot and cold water supplies will come from. But first, you must isolate the source. To drain the water in the pipes, turn off the stopcock that’s typically found beneath the sink. Then open the hot and cold faucets, and you’re good to go.
  • Run the water through your shower. Check and thoroughly follow the instructions that come with your valve. After that, feed water supplies to the correct sides. Hot water should be on the left and cold on the right. 
  • Clean and flush the pipework out of any dirt. This is to prevent your new valve from getting damaged. To do this, you must turn the water off and remove the ends. Catch the water that’s flowing from it to determine if it’s now clean enough. After that, shut off the stopcock. 
  • Determine how much outlet pipe is needed. You can press your new thermostatic valve against the wall and mark it with a pencil. Then gauge how much pipe will be needed to install it flush with the wall.
  • Cut and drill. After carefully cutting the pipes to their required length, drill the holes for your valve using a diamond driller head. 
  • Use a compression olive to ensure that the valve is watertight. Fasten one up for each inlet and screw them in position. 
  • And now we connect the thermostatic valve. Make sure that the cold and hot pipes are aligned and fully inserted. Now, use an adjustable spanner to screw your shower valve into the wall and tighten the retaining nuts.

Do I need a rough-in valve?

Installing a shower rough in valve

You definitely need a shower rough in valve if you don’t want to get surprised out of your hazy morning showers with a blast of hot water.

But aside from your comfort, it’s also necessary to keep your shower area (and other water fixtures at home) child-proof and safe. 

A sudden blast of water that’s too hot or too cold may cause the person using it to get started and slip or fall. Not to mention any burns that scalding hot water may cause.

But aside from that…

…some buildings and apartment complexes also require the residents to follow codes when it comes to plumbing and your shower area, and most of them would require you to get one.

What is the difference between a rough-in valve and a diverter valve?

Shower rough in VS diverter valve

Sometimes, a rough-in valve and a diverter valve are being mentioned interchangeably. But in reality, they play really different roles from each other.

For one, you must have already known that a rough-in valve is a shower valve that’s mostly installed inside your wall, just behind the shower handles. Aside from turning the water on and off, it also works to control the water temperature according to your liking. 

It also acts as a safeguard for your shower and water fixtures by keeping super hot or freezing water from blasting you and your taps. 

But despite this…

…a rough-in valve doesn’t have the ability to control your shower’s water pressure. 

On the other hand, a diverter valve is a tool for showers with more than one water outlet. If you have a handheld showerhead, a fixed showerhead, and even a tub faucet, then you definitely need a diverter valve.

A diverter valve works in a way that it diverts the water to different outlets in your bathroom so you can use both of your showerheads at the same time.

Unlike the rough-in valve…

…a diverter valve doesn’t have the ability to control your water’s temperature. 

How do you know what shower cartridge you need?

Every bathroom or the best shower faucet comes with a cartridge upon purchase. But of course, there comes a time when they need to be replaced, too.

Before getting a new shower cartridge, make sure you know your former cartridge’s brand, model, and identification to avoid any pitfalls along the way. 

Usually, a shower cartridge’s brand is very easy to spot. It’s typically engraved somewhere on the unit. 

But aside from that…

…you can also measure its dimensions and number of splines, then compare it with references such as this one.

What Is a Shower Valve with Stops?

Shower Valve with Stops

Sometimes called integral stops or even screwdriver stops, shower valve stops are built-in shut-offs in a valve. 

Simply put, a shower valve stop allows its user to shut the water off on one of the faucets in the house without having to shut off all water fixtures so that other people can continue using it too. 

While useful…

…they’re not very necessary in the installation of a shower valve, and a shower trim kit could work even without it. 

How do you Access Shower Rough-in Screwdriver Stops?

Shower trim kit removal

The first step in accessing the rough-in valve stops is removing the shower trim kit. It means removing the handles and even the head. 

After removing the trim kit, you should see the stops where the cold and hot lines enter the rough-in valve through inlets. 

Remember to turn off the hot and cold handles first. 

The next step should be easy. All you have to do is turn the screws using a screwdriver. Although today, different brands and models may also have different ways to turn the stops, it should be intuitive and easy.

How do you Operate the Shower Rough-in Valve’s Integral Stops?

Operating a shower rough-in valve’s screwdriver stops is pretty easy and manual. As mentioned earlier, all you need to do is to turn them with a screwdriver.

This way, turning the stops means blocking the flow of water. There’s a separate stop for both hot and cold water lines, so make sure to turn both of them.

How would you know if they’re already shut off?

You’ll feel that the stops are already tight and can’t turn anymore. That means that they’re now fully closed. 

Conclusion: What Is a Rough In Valve for a Shower?

Shower rough in valve with cap

If you want to be completely familiar with your bathroom, it pays to know every single hardware and fixture there are. 

Not only will it save you money in the long run, but it also lets you fix them by yourself and in a way that suits your liking.

Now, if you’re left wondering…

…a shower valve is a great investment if you have children at home or even if you’re just sharing with other people. Having one doesn’t only make everyone more comfortable but safe, as well.

A simple mixer valve will probably do if you’re a small family. But if you want a real investment that lasts long, getting a good thermostatic shower valve or even an electric valve is the way to go.

After all, nothing beats coming home to a warm shower without worrying about accidents and pipe issues.