Our Best Bathroom Addition Tips – Cost To Add a Bathroom In 2023

In Los Angeles and Southern California, quite a few of the homes built before the 1970s were constructed with only a limited number of bathrooms. Although this was the trend many decades ago, modern homeowners often prefer to have more than one or two bathrooms in their homes.  Thus, it’s quite common for homeowners to add a bathroom to their homes. A bathroom addition makes any home more comfortable and functional, as well as adds long-term resale value.  

Here at GreatBuildz, we speak with clients every day who are considering a bathroom addition to their home. GreatBuildz is a free service that connects homeowners with reliable, pre-screened home improvement contractors, then provides ongoing project support to ensure a stress-free experience. In this blog, we’ll share some ideas, costs and tips about adding a bathroom to your home/garage and finding the best contractors for your project.

Related: Estimate the cost of your remodel with our bathroom remodel cost calculator

How much does it cost to add a bathroom to your house?

Bathroom Addition Grey Marble

The price of a bathroom addition will really depend on a few things.  First, it will depend on where the bathroom is being installed… as in inside the current floorplan of the house (say in a closet), inside the garage, or as a brand-new structure to expand the footprint of the home.

Adding a bathroom inside the house might cost you $30k-40k, depending on a few things like proximity to the plumbing pipes. Installing a bathroom in the garage might be a bit more expensive ($5k-20k more) because the space will have to be ‘finished’ with items like drywall, lighting, and HVAC to replicate a room inside your home. Finally, building a brand-new bathroom addition outside your existing home footprint will cost you between $50k-100k.

The price of a new bathroom will also greatly depend on its size and amenities. Clearly, a half-bath with only a toilet and sink will be less expensive than a full bathroom with a tub or shower. And a luxurious, master bathroom will come with the biggest budget.  

Although you can start your budgeting with the basic rough bathroom addition cost estimates above, the only way to get accurate cost figures is to discuss your project and plans with a few good general contractors.     

How much value does a bathroom addition bring?

Your home value will always go up if you add a bathroom. On the west coast of the United States, the average return is about 67 percent, however, this figure can vary greatly depending on the size and type of bathroom you are adding to your house.

Different Bathroom Layout/Plan Options

Bathroom Addition Bathtub

Half-bath (powder room): If you really just need an additional bathroom for guests so they don’t have to use the same bathroom as the household members, a half-bath will work great. It’s comprised of just a toilet and a vanity/sink, so you can skip the expense of a shower/bathtub. A half-bath can be pretty compact and fit into as little as 25 square feet, so it’s sometimes possible to create this bathroom from a closet or other small interior space.

Full bath (or ¾ bath): This type of bathroom includes a shower or shower/tub combo and is ideal for use by the residents of the home, especially if too many people are currently sharing one bathroom (a ¾ bath has no tub, just a shower).  A standard size full bathroom is approximately 40sf (8ft long x 5ft wide), but may need to be larger if the homeowner wants double sinks, linen cabinets, etc.

Master bath: Clearly, a master bath needs to be located adjacent to the master bedroom within a suite that should include the bedroom, bathroom & closet.  The size can range from a standard 40sf layout up to 200sf or bigger depending on what you want to include.  Often a master bath has double vanities/sinks, a toilet, and a separate tub and shower. It can also include a linen cabinet or a full closet.

What affects the cost of a bathroom addition?

Bathroom Addition Double Vanity

There are items and costs in your bathroom addition that you cannot control, for the most part, because they are fixed costs and aren’t optional. These include things like a new foundation, wall framing, drywall, roof, wiring, plumbing lines, insulation, stucco, etc.  These are the categories that don’t change regardless if you’re building on a budget or you’re sparing no expense.    

Alternatively, there are a whole host of items that go into a new bathroom addition that affect your costs & budget which are based on your choices, with some examples below:

Windows: You don’t need a window (or skylight) in your bathroom, but it will certainly make the space lighter & brighter. The costs of windows vary greatly based on your selection. And, you’ll want to choose windows that approximate the existing windows in your house. An average window might cost you $500-$1,000 including installation.

Bathroom Flooring: Cost will vary greatly depending on whether you select a cheaper material like ceramic tile or vinyl plank versus a more expensive option like marble, stone, or exotic tile.  Bathroom flooring will start at $10 per square foot and could go upwards of $40 per square foot for luxury materials (including installation).

Lighting: Recessed lights are reasonably inexpensive and might cost between $100-$200 per light installed.  Other lighting costs will depend on the fixtures you choose and ranges from less than $100 to… very expensive. 

Bathroom Addition Gold Vanity

Shower Tile: Tile is expensive to install regardless of the style you choose because it is labor-intensive.  You can save costs by selecting an inexpensive porcelain tile that comes in larger pieces. Larger tiles take less time to install.  Conversely, if you’re selecting an expensive tile, especially in a small format, the costs will increase substantially. The tile material cost can range from $1/sf on the low end to well over $20/sf for materials such as glass or marble. Add $10-20/per sf for installation.  

Bathroom Fixtures: Items like faucets and shower hardware are available at a reasonable price at retailers like Lowes and usually come in basic styles and finishes like chrome or brushed nickel.  For a higher-end look and style in finishes like gold or matte black, you will have to spend significantly more at places like Ferguson

Bathroom Cabinets & Vanities: You can find bathroom vanities in standard sizes and styles at the big home improvement stores or online. These work well for a half-bath, powder room, or standard size full bath and range in price from $150-$1,000. For a large or master bathroom, you will likely want a double vanity with two sinks in a size between 60″-72”, and this could range in price from $1,000-$2,000 and usually include the vanity cabinet, countertop & sinks.

Alternatively, if you need to create a custom vanity in a specific size or want additional bathroom cabinetry, it will require your contractor to have it custom built.  You can also select a custom countertop to go with it and any number of sink options. In this case, you’re looking at spending at least $2,000 and potentially up to $5,000 or more.   

Plumbing: Keep in mind that one of the major expenses in adding a bathroom in Los Angeles or Southern California is connecting it to the existing water and plumbing pipes. If these exist in proximity to your new bathroom location, that will obviously save some costs.

The most challenging plumbing entails the sewer/waste lines that need to run from your new bathroom to existing pipes in your home. These run under the house, but their exact location will depend on your style of foundation. If you have a raised foundation (with a crawlspace), those lines are reasonably accessible under the house. On the other hand, if you have a slab foundation, those pipes are inside the concrete slab. To access these, it requires cutting the concrete slab, which increases the cost of the project.

For a full cost breakdown, check out my blog about bathroom remodeling costs.

What’s the process to create a bathroom addition?

Bathroom Addition Flower Wall

After doing your research on costs and deciding how you want to pay for the addition, the next steps are to reach out to a few contractors.  The contractor will probably put you in touch with an architect with whom you can discuss the costs of the building plans (likely $8,000-$15,000). The contractor is well suited to speak with you about the true cost of the project, the duration of construction, and other construction considerations.

With a project such as a bathroom addition, you will need a general contractor because the job requires tile, plumbing, electrical, framing, painting, etc. A general contractor with a B-license is the only type of contractor qualified and authorized to do projects with a multitude of different trades required. Make sure the bathroom contractor you hire has an active license and can provide you proof of insurance…both liability insurance and workers compensation. In addition, ask them to add you as an additional insured on their policy and provide you with an insurance certificate indicating this.

You can expect that it might take a month or two for the architect to develop a full set of building plans and get them approved through your building department’s plan check process. Once you start construction, it’s likely to take less than 2 months for completion.

What’s nice about a bathroom addition (versus a home remodel) is the work is all being done ‘outside’ of your existing living space, so you won’t have to deal with the dust and inconvenience of living without a bathroom.   

At the outset, a good contractor can give you a rough budget for a bathroom addition based on their experience of doing similar projects in the past, but they may tell you that they can’t provide an exact estimate until your plans are complete.

How can I find a good bathroom addition contractor?

Bathroom Addition Tan Cabinets

Finding a great, reliable contractor isn’t always easy.  In Los Angeles County alone, there are over 20,000 licensed general contractors to sift through for a bathroom remodeler, so it’s not always easy to tell the good from the bad. The best way to find some good bathroom contractors is to ask friends, neighbors, or trusted colleagues for recommendations of someone they’ve used and liked. If you ask for recommendations on social media, you should only trust suggestions from ‘real life’ friends. People you don’t know personally are often biased (they’ll recommend their cousin the contractor, etc).   

If you don’t get enough good recommendations from friends and relatives, consider using a service that performs intensive contractor screening and offers personalized introductions to good general contractors (www.GreatBuildz.com or similar). Don’t just pick a random home contractor from a flyer that came in your junk mail or from a nationwide contractor listing site.  See my blog about how to find and hire the best contractors.  

Related: How Do You Compare Contractor Bids For Your Home Remodel?

When it comes to planning and coordinating a bathroom addition to your home, you shouldn’t have to go it alone – GreatBuildz can help simplify your renovation experience.  


GreatBuildz is a free service that connects homeowners in Los Angeles, Orange County, Ventura County and San Diego with reliable, thoroughly screened general contractors and provides project support from start to finish. Call now (818.317.3567) to chat with a real person about your next renovation project or visit our website for more information: www.greatbuildz.com.

Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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