Manufactured Home Washing Machine Outlet Boxes Guide – Safeguard Your Washing Machine and Plumbing

The perfect manufactured home washing machine outlet boxes should be designed to install in the drywall.

Numerous benefits come with installing a WMOB somewhere in the laundry room of your home. They include:

  • The crisp and finished appearance of your renovation work
  • Freeing up some floor space by removing the need for laundry sinks to drain your washing machine
  • Safe, quick access to water outlet shut off valves in the event an emergency occurs

But, with numerous options available in the market, how do you choose the right outlet box for your washer?

Washing Machine Outlet Boxes For Mobile Homes – 9 Shopping Factors

Here are the factors to put into consideration when selecting one:

  • Water Supply & Drainage Configuration
  • Type of Valve – Quarter Turn Valve v/s Single Lever
  • Structural Considerations
  • Compatibility with Different Connector Types
  • Anti-Water Hammer Protection
  • Flood Protection Features
  • Brand
  • Cost & Budget
  • Special Considerations

1. Water Supply & Drainage Configuration

The first thing you should check before even deciding which type of box you want is the restrictions that may be present at the point of installation.

Start by determining whether there are restrictions that may create problems during the installation process (e.g. pipe location, pipe material, wall cavity space, etc.).

While most outlet boxes support a range of connections, not all of them will be compatible with pretty every layout.

If the water supply is from above,

  • choose a box that supports inverted installation, or
  • one that can easily accommodate valves that permit above water supply and bottom drainage.

Oatey is a top supplier of outlet boxes and all of their products can be installed in the inverted position, except for their MODA and Eliminator families of fire-rated boxes.

Along with how water will be supplied to the box, how water will leave it, and where the box will drain must be considered as well.

If you require an arrangement that must accommodate additional drainage, say, a condensate line, choose a box that provides extra drainage options.

Alternatively, you can choose the Oatey’s 2 x 4 box  which also supports additional drainage. The best thing about this model is that it can be installed inverted and provides knockouts in all four corners to support maximum flexibility during drain line installation.

Most stores and suppliers don’t label their versatile boxes as so. Rather, they opt for a technical-sounding alternative “universal.”

The Oatey’s Quadtro line of boxes consists of universal options, such as this:

  • Oatey 38569 Quadtro Washing Machine Outlet Box  – Cost: $41: A member of the extended Quadtro family of boxes whose members feature valves that can be shifted to support different layouts that require their drains to be right, left, or straddle, or even emerge from above.

If you don’t want the versatile/universal kind and would rather be specific with type, you can choose between the center drain and offset.

2. Type of Valve – Quarter Turn Valve v/s Single Lever

What type of valve do you want your outlet box to have?

WMOBs come with one of the two types of valves –

  • quarter-turn valve
  • single lever valve.

Quarter Turn Valves

Quarter turn valves are bi-directional and they can be easily opened by a simple quarter-turn of the vane, plug, ball, disc, or any other device used for opening or closing.

Boxes that come with this type of valve can be quite expensive, but they are the most reliable valves out there.

Most of the valves we will find in outlet boxes today feature positive action balls to control the flow of water from the washer to the outside.

If you are looking for a problem-free outlet box, you might want to choose a product with this valve.

Single Lever Valves

A Single Lever valve, on another hand, is capable of controlling water flow in both hot water and cold water hoses passing through the outlet box.

It shuts the water flow simultaneously when necessary to protect the hoses and machine parts.

So, if you want an outlet box that can control water in the two hoses at the same time, you might want to buy one with a single level valve inside.

Note that some boxes come with two valves while others feature a single valve, but products featuring both of these valves are extremely rare.

3. Structural Considerations

There is more to washing machine outlet boxes than plumbing configurations.

The space where you will install the box is one of the most critical parts of the project and one that requires special consideration.

The structural configuration of this space needs to be put into account as well.

Because this space comes in no specific standardized design, it only makes sense that you go for a box with a modular design that can offer the versatility you need.

Such a box will permit you to add an outlet box in any configuration you want, including straddling your studs in such a way that water supply is on one side and drainage is one the other side, or better yet, separate walls!

Oatey has a collection of such boxes.

The MODA family has a range of options that you might want to try out.

What if limited space is the major hindrance? In this case, you will need the most compact yet versatile box you can ever lay your hands in.

A 1/2” box would still do, such as the Sioux Chief Washing Machine Outlet Box 1/2”.

Outey’s Centro II is a line of probably the most compact boxes that you could find in your local store. Boxes in this line measure just 1/4″, meaning they can fit in the tightest locations you may have in your laundry room.

4. Compatibility with Different Connector Types

Many buyers don’t consider the compatibility of the outlet box with connectors of the piping until it’s too late.

The reason why you need to factor in the compatibility is the diverse nature of these pipes – they can feature one of the many types of connectors used out there.

Most of the pipes used in the installation of washing machines feature CPVC, PEX, Copper, or PE-RT connectors.

First, check the kind of connector featured on the outlet pipes. Thereafter, look for boxes labeled as compatible with those connectors. Trying to connect a box to pipes it was not designed for could mean frequent malfunctions.

Most boxes are compatible with one or several of these connectors. The more the connectors the box supports, the better it is for your project.

Copper Sweat connector

“Copper Sweat” means the connector is made from copper and was soldered on the joint or any other part of the pipe.

PEX connectors

These connectors are made from the same material used to make PEX tubing, normally a cross-linked polyethylene. They are cheap and easier to use.

PEX has a bad reputation for leaking its constituent compounds in fluids, but since we are talking about refuse water from the washer, you’re good to consider its connectors and whether your outlet box of choice will work with them.

CPVC connectors

These connectors are made from chlorinated polyvinyl chloride. If the outlet box is compatible with PEX connectors, then it is more likely to be compatible with CPVC.

Push-to-connect connectors

These connectors have nothing unique other than providing a secure and unique connection without the need for crimping, joining material, or soldering.

All you need to do to install it is to push the parts into the pipe and the outlet box until it stops.

MIP connectors

The “Male Iron Piper” is the direct opposite of the FIP connector.

If your washer is connected to heavy-duty pipes, they are more likely to feature MIP connectors.

5. Flood Protection Features

One of the top causative agents of household flooding is a washing machine.

If the inlet or outlet pipes are faulty, jets of uncontrolled may end up gushing on the floor.

These floods often cause devastating damages.

The worst flooding that could occur is that originating from inlet pipes.

Because water is always waiting to force its way past the valves into the washer, faulty inlet valves are more likely to flood your home when you are not around – it can strike any time.

Outlet boxes too can be flood spots because they act as a control center for water leaving the washer.

That’s why they should possess flood prevention mechanisms just in case. Floods originating from or close to the outlet box tend to be less devastating because they only occur when the washer is working.

The most commonly used anti-flooding system in both the inlet and outlet points of the washer is the FloodStop (FS 3/4-H90-V4) system.

However, not just any outlet box will feature valves with it.

It is mainly used with two models of outlet boxes – Ox Box and the Double Outlet Box.

There exist other technologies but Flood FloodStop (FS 3/4-H90-V4) happens to be the most preferable.

Since they tend to be standalone devices rather than a system add-on on the valves or parts of the outlet box, you can expect different manufacturers to avail anti-flooding systems that work with outlets boxes from specific manufactures.

When buying an outlet box, check whether it is compatible with any of the common anti-flooding devices in the market.

6. Water Hammer Protection

Water hammers can be a real headache for larger washing machines.

A water hammer occurs in any water supply piping when water stops or changes direction abruptly. It normally manifests itself in form of a jolt. When a washing machine stops filling or emptying, for example, a water hammer will occur unless the inlet and outlet boxes are equipped with effective mitigating devices.

In extreme cases, frequent water hammers will damage the rest of the plumbing and call for expensive reinstallation or repair work. The valves may fail to work properly if they are subjected to frequent shocks frim water hammers.

Reducing the pressure of water flowing in your home is normally the best rectifier, but it only works for inlet water flow, outlet line which outlet boxes control.

Most outlet boxes sold today feature valves with inbuilt water hammer arresters, but it is good to check whether your model of choice is equipped with one. Third-party arresters can be installed but that’s usually tedious and will cost you extra money.

A few members of Sioux Chief’s Ox Box outlet boxes feature valves with water hammer arrestors. This brand is also a top manufacturer of valves – if you choose one of their outlet box models with no anti-water hammer enabled valve, you can buy a compatible box and valves with it.

The biggest supplier of water hammer arrestor enabled outlet box is EASTMAN:

7. Cost & Budget

How much does each of your prospective models cost?

How much money are you willing to spend on one unit?

The cost of an outlet box and that of installing it are normally calculated as part of the cost of installing the rest of the washer. But, what if you are replacing an older box?

The average cost of the product is between $40 and $55. Most of the models you will find at Lowes, Home Depot, and Amazon costs between $10 and $105.

A washer’s outlet box can be costly, especially if you are thinking of the high-end options with type with many technologies inside. Before even committing yourself to acquire one, prepare a well-thought budget first.

That budget serves to help you stay focused on what you need and lets you allocate the right amount of money for acquisition. Budgeting helps you avoid overspending.

  • Start by deciding the maximum and minimum amount of money you’re willing to spend.
  • If you need a product with more features, one that supports knockouts, factor in the specific additional features, and if you really need it.
  • An outlet box that supports 4 knockouts on all four corners will cost more than one that supports less.
  • Also, be critical of the size just so you don’t end up paying for a larger unit that you don’t even need.

Once you decide the specific amount of money to spend, it becomes way easier to come up with a list of features the cooktop must have and those that you needed but are willing to trade-off with others because of the cost.

8. Brand

It is easy to end up with fake and problem-prone washer parts if you are not particular with brands.

The world of washing machine accessories and parts is full of imitators.

And just because a brand is out there doesn’t mean their products are quality enough. You want a durable outlet box that will keep delivering service for a long time without malfunctioning.

If other parts of the system are made by a given brand, you might want to add an outlet box from that same brand.

If you want decent outlet boxes and associated accessories, check with

  • Oatley (which is something sort of an authority brand in this segment)
  • Symmons
  • Dyconn
  • Everbilt
  • Sharkbite
  • Apollo
  • PEXLock
  • Guy Gray
  • Tectite.

Sioux Chief produces some impressive products too.

9. Special Considerations

You might need specialized boxes, but it depends on the application.

Different homes have different needs and things to watch out for. For instance:

Is fire a major worry?

You may have already selected a washer with this issue in mind, but you also need to choose a box made from fire-resistant material.

Consider buying a fire-rated box.

They are made from BMC – bulk molding compound or UL-certified intumescent materials.

Are you anticipating high impacts on the wall on an area close to where the box will be installed?

Choose a box made from high impact material such as polystyrene (Manufacturers are starting to embrace HIPS – high impact polystyrene).

Now that you have selected the best outlet box for your washer, consider installing it the same height as your flood level rim (slightly top of the designated drainage outlet) which is normally between 32” and 34” above the floor.


Owing to the critical role outlet boxes play in the proper function of the washing machine, you want to be the best and top quality product you can find in the store.

The first factor you should bear in mind is water supply and drainage configuration of the product.

The type of valve (quarter turn valve v/s single lever) used by the box should be factored in as well. The box should be compatible with different types of valves.

To prevent damages caused by the water hammer, the box should come with arrestors.

Other factors to consider are flood protection features, the brand, and cost v/s your budget.