How To Add Plumbing To A Garage

How To Add Plumbing To A Garage
  • Author: Amanda Arnold
  • Posted On: November 11, 2021
  • Updated On: August 21, 2023

Remodeling your detached garage is a terrific method to increase the value of your property. Maybe you plan on renting it or turning it into a garage apartment. However, you’ll have to figure out what’s allowed regarding plumbing.

Continue reading to learn if a detached garage bathroom is possible. Most of us would appreciate some extra space in our homes. As a result, more people are converting their sheds, garages, and outbuildings into valuable spaces. So, how can you turn your outbuilding into the ideal extra living space?

Garages are a frequent location for water heaters. It’s an excellent time to consider installing a new one, whether it’s a tank or tankless design, if you’re remodeling or building. Running gas lines as needed is also part of the plumbing; if you’re not building a new line, consider bringing your existing one up to code if it isn’t already.

How Much Will Plumbing To A garage Cost?

For many homeowners considering this renovation, the first question that comes to mind is: how much will it cost? A plumber’s quote for running plumbing to your detached garage may be affected by several things. Consider the following points: The price of your pipes and valves will influence the price of your plumbing.


Concrete garage foundations are more expensive because the plumber must drill through them. There are, nevertheless, ways to cut costs. The central sewer line depth also matters. The job will cost more if your main sewer line is more profound than usual.

If the garage is insulated, water heaters can be installed inside, providing hot water more efficiently than water heaters positioned farther away. It’s possible that you won’t require hot water. If you want to install plumbing in your garage, you’ll need to add ventilation, or you’ll have moisture and condensation problems.

A plumbing vent must also be installed on the garage’s roof. Running a plumbing connection between a garage and a further away house, or if the house’s plumbing isn’t close enough, will be more expensive.

Steps To Install Garage With Bathroom

Hire The Professionals For Plumbing In The Garage

Unless you’re a seasoned DIYer, retrofitting a garage for plumbing is best left to the professionals. When you install a sink, tub, shower, washing machine, or toilet, you’ll need to run water lines, connect drain lines, and install shutoff valves.


Drain lines must be run through the floor. However, water lines can be routed through the walls. If the work is being done on an existing foundation, cut the garage floor to make room for the pipes. These plumbing issues are part of the early planning for new construction.

In addition, depending on the location, your line connection will include excavating or trenching through your yard or driveway and connecting to a sewer or septic system.

Prepare The Garage

The garage needs to be prepared to be used as an indoor living space. You can store anything in the garage in your basement, shed, or a storage area.

Layout Subbfloor


Building the subfloor is the next phase, which is important since it serves as the framework for everything else. Before adding the subfloor on top of the floor, ensure it is structurally sound. The objective is to maintain a consistent floor height throughout the house.

Insulate the subfloor with fiberglass insulation before installing the tongue and groove plywood. To the subfloor framing, glue the plywood.

Insulate Ceiling

Spray foam insulation for the garage ceiling will save you time and effort. Every interior wall that has fiberglass insulation should be covered in plasterboard.

Determine The Plumbing Location Carefully


Consider where water-dependent appliances should be placed. You’ll want to keep them out of the way but in a convenient location. Washing machines and dryers are most valuable near the house’s main entrance. Closer proximity to the garage doors may make sense for utility sinks, tubs, or bath components.

Adding a basin for a washing machine is an excellent option to handle spills or leaks. A drain line for the washing machine is necessary, but a floor drain is also beneficial. Install a drain in a central spot on the garage floor while installing drain lines for appliances and fixtures.

Install Water Lines

Check that the distance between the sink, toilet, and shower is sufficient. Finally, don’t be discouraged if your design does not correspond to the bathroom’s overall arrangement. You want to set a deadline but don’t be surprised if the plan doesn’t meet it because weather conditions can change the deadline dramatically.


Plumbing is another project that is frequently left to professionals. Adding everything from a sink to a toilet necessitates installing water and drain pipes. To add water lines, you’ll have to remove the walls and replace them with new ones with water lines built into them.

On the other hand, drain lines must be run through the floor, so you’ll have to cut the garage floor to attach the pipes.

Add Gas Lines

Finally, a location for your water heater is required. Before shopping for a water heater, consult a professional to see if a gas line must be installed in your garage. To make the water heater function, you’ll need many gas lines coming through the walls to keep it plugged in.


Whether you or your plumber is working in concrete or the ground, you must dig up the old pipes and cut holes in the garage and maybe the house to make way for the new ones. The fittings, plumbing, and ventilation required to make the system work will be installed by your plumber.

Keep in mind that water will need to flow toward the drain. Thus the floor will need to slant toward it.

Frequently Asked Questions

Is it safe to put a bathroom in the garage?

Of course, yes! For example, you could easily install a shower and a bath in a garage bathroom or add a wet room to turn the space into your home spa. The possibilities are truly endless, especially if you have a sizable budget to deal with.

Is it legal to build a portable garage bathroom?

You should check with your local building authority to see if installing a no-water toilet in your garage is permitted before you do so. In some places, if you have access to a septic system, a composting toilet cannot be installed in your garage or house.

Is it reliable to install a garage bathroom without plumbing?

If a toilet is not part of an addition to the building, planning approval is typically not needed to install one on a property.

Final Thoughts

It’s conceivable that you’ll require planning approval if you want to modify the use of your outbuilding, especially if you want to convert it to a bedroom or install permanent plumbing. According to the regulations, any incidental use, such as a pastime or something you wouldn’t do at home, will not require approval.

However, an authorization may be required for sleeping, showering, cooking, or other activities ordinarily done in your home.

Building the detached garage of your dreams is feasible, but it’ll take some research and elbow labor. Arm yourself with the knowledge to move forward confidently with your current renovation. Most importantly, when it comes to ventilation, always seek professional advice.

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Author: Amanda Arnold

Amanda has been working with ConstructionHow since 2021. Her experience spans over 5 years in the creative niche such as home decor and trends, landscaping, renovations, and custom architectural values. As a home designer expert, she has a keen eye for the latest home improvement trends with accurate facts that readers find impossible to ignore. Being invested in home-building trends is how she has gained her lucrative expertise exploring more to bring a positive ambiance for all homeowners (and even tenants!). Currently, she lives in a beautiful beach home, a source of fascination for her.