Given the lower demand amongst house hunters for a garage on the property and the increased desire of homeowners to have more space, garage conversions have become highly popular in recent years. There is often so much space to play with in the garage unit that the world is your oyster when thinking of creative ways to use the extra square footage. If you turn the garage into a livable area, a bathroom is essential, and while it may cost a good chunk of change, the investment is more than worthwhile. Before you start, check out these tips on adding a bathroom to a garage and ensure you get it right.

Tips for Adding a Bathroom to a Garage

Local Laws

The first and most important aspect of the planning stage will be to check local building codes and what they state for those looking to add a bathroom to an attached or detached garage. A garage bathroom will require a water supply, perhaps new drainage pipes, updates to existing plumbing or altogether new plumbing, and so much more.

These laws will change depending on which state you live in and which municipality you live in. For example, in California, any garage conversion must have, at the very least, a toilet, sink, and shower to be legally inhabited. Permits are also required if you are making changes to the existing plumbing.

Obtaining Permits

Obtaining permits for installing a garage bathroom, or indeed the conversion itself is almost always necessary. Building codes cover so many aspects of construction that failure to get permission may mean you aren’t legally allowed to complete the work.

This kind of project may require new water lines, changing access to the main sewer, adding or removing underground pipes, moving a wall or two, and even installing new electrics, all likely requiring permits. Some construction services may tell you that permits aren’t essential and that the job will be done faster without them. This is bad advice, and you should check with your local building authority or consult the international residential code, which can be found online.

adding a bathroom to a detached garage

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Plumbing and Electrical

The biggest challenges when installing a bathroom in the garage are the plumbing and electrics. Most garages have a power supply, but before installing a garage bathroom, it will be prudent to check just how much power you have. Constant and increased power usage may require new wiring to cope with the increase.

The waterworks present the biggest challenge for your new bathroom, as the large majority of garages just don’t have the kind of water supply that you will need. This may be easier if you have an attached garage, as you can utilize the water pipes from the main property. If, however, you have a detached garage, this can pose all kinds of problems.

Much depends on the location of the garage, as the further away it is from the home, the further away it will be from the main sewer. This distance also means that water pressure can be an issue, as any existing pipes just won’t be able to deal with the increased demand for water.

Ripping up and replacing the concrete floor to install new pipes adds to the time and the project’s final price. Even with attached garages that have a water supply, drainage will need to be addressed, and it may be that the entire layout has to change as a result.


When measuring for your bathroom project, it is always essential to use professionals rather than aiming to do it as a beginner. There are factors to consider, such as leaving space for the subfloor, adding pipes for heated flooring or drainage pipes, and allowing for ventilation.

First, you need to know how many square feet the garage measures, then decide what proportion you want as a bathroom, and then begin to measure height and area accurately. Homeowners also need to know what exactly they will be putting in the bathroom, as the last thing you want is to put joists up and add walls if the bathtub doesn’t fit or if you don’t have enough space for the shower entry.

Planning The Bathroom Layout

The layout for your garage bathroom will be driven by aspects such as new piping, drainage requirements, and any potential limitations, such as existing foundations. Additionally, you should be thinking about what you want in the bathroom.

Some will add a toilet, and those looking to create a habitable space will add a shower, too. You may even want to go all out, get a big tub for your garage bathroom, and turn it into a relaxing sanctuary.

Once you know what you want, you can think about where the toilet or shower will go to ensure the bathroom looks great and is easy to use. This is a crucial step for those looking to convert their garage for elderly family members, who may need to install a wet room rather than a standard shower and ensure the toilet is fully accessible.

In this case, you may require more clearance in front of the shower area, increasing the overall size of the bathroom. Finally, don’t forget to make plans for a water heater if you decide to install one in the bathroom. These will sit outside of the room and will take up space.

bathroom in the garage

Install Ventilation

Adding a bathroom to the garage isn’t as simple as it appears, and there are lots of important details to remember, such as planning to install ventilation. Few garages already have windows, and adding holes in the walls is costly and time-consuming. You will need vents and moisture-resistant materials to combat humidity and build-up.

Nonetheless, this is critical to avoid a build-up of water throughout the garage, which can have negative consequences like mold and rot, not to mention foul odors. A moisture-resistant floor, for example, can only do so much so windows and air vents must be installed.

Even if you only install a toilet and a sink, a window or air vent is still necessary in your garage bathroom.

cost of adding a bathroom to a garage

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Cost To Add A Bathroom To A Garage

As we mentioned at the top, adding a bathroom won’t be cheap, but it will be worth doing. This project ensures your garage is livable, complete with a toilet and shower, to add comfort and convenience to your new space.

Regarding how much this project will cost, it is easier to look at that based purely on price per foot to give a general idea of what you’ll be looking at. As you can imagine, there is a range of features you could install that will drive the price up, such as a heated floor, towel rails, or even a toilet seat!

Installing the bathroom from a construction point of view will require similar labor, time, and materials based on how many square feet you’re dealing with. Currently, the average cost per square foot of adding a bathroom to the garage is $200-$300. This is a good figure to bear in mind before you commence this project.

Once you have the basic layout and measurements, you will have a base price for the project. Extra costs won’t just come from the materials you choose, the quality of the plumber you hire, or how pricy the taps are; you have to account for the details. Permits will cost you money to get started, a new water heater will not be cheap, problems with old underground pipes can arise, and you may even encounter issues with the sewer.

The average price is a guide, but be sure you have some contingency funds because problems could quickly happen.

How Hard is it to Add Plumbing to a Garage?

Homeowners have two choices when installing plumbing in the garage: underground or overground. Most prefer plumbing below the floor, although this comes at a higher price, as the plumber will have to break the ground. Distance is another key component when adding a bathroom, and that is why detached garage bathrooms are more expensive and take longer to complete.

Do You Need Planning Permission to Put a Toilet and Shower in a Garage?

When talking permits, neither local nor state residential codes require permits to add a toilet or shower to the garage. If you are changing the waste pipe, you will need permission. You will also need permission when adding a bathroom if you change existing plumbing or electrical lines. Should you opt to add a water heater to the garage, this may also require permission, depending on where you reside.


In conclusion, while the process of adding a bathroom to your garage may come with its fair share of challenges, it undeniably offers numerous advantages. Despite potential pipe and drain issues that might arise, as well as the costs involved and the work required, this endeavor can significantly enhance your property’s value and transform your garage into an ideal living space. The convenience and functionality a garage bathroom provides cannot be understated, offering additional comfort and versatility to your home. So, if you’re considering this renovation project, the long-term benefits make it a worthwhile investment in your property and lifestyle.