Bathroom Addition Tips – Cost To Add a Bathroom In Los Angeles

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. While that was once all the rage, modern homeowners are more likely to prefer having more than one or two bathrooms in their homes. Enter: the bathroom addition. Adding a bathroom makes any home more comfortable and functional, as well as adds long-term resale value, making it one of the most popular home renovation projects out there.

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

Key Takeaways

  • The cost of adding a bathroom to your house varies based on its location within the property, ranging from $30k-40k for an internal addition to $50k-100k for a new structure outside the existing footprint.
  • Adding a bathroom generally increases your home’s value, with an average return of about 67% on the west coast of the United States, although this figure can fluctuate based on the size and type of bathroom.
  • Various factors impact the cost of a bathroom addition, including the type of layout chosen, the selection of materials like flooring, lighting, and fixtures, as well as plumbing requirements and accessibility to existing pipes.

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, the cost to add a half bathroom 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 comprises 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 of whether 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 and $200 per light installed.  Other lighting costs will depend on the fixtures you choose and range 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 to $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 the 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. Accessing these 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 two 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.

Cost-saving tips and strategies

Cost-saving tips and strategies can significantly reduce the overall expenses of a bathroom addition project without compromising on quality or functionality. Here are several effective approaches:

  • Consider refurbishing existing fixtures and cabinetry instead of replacing them entirely. Refinishing surfaces, updating hardware, or repainting cabinets can give them a fresh look at a fraction of the cost of new installations.
  • Opt for cost-effective materials without sacrificing durability or aesthetics. Explore alternative options such as ceramic or porcelain tiles instead of expensive natural stone, and laminate countertops instead of granite or quartz.
  • Prioritize essential features and amenities while minimizing extravagant additions. Focus on functional elements like efficient plumbing fixtures, practical lighting solutions, and durable flooring materials that offer value for money.
  • DIY tasks can save on labor costs, provided they align with your skill level and safety considerations. Painting, demolition, and minor installations are common DIY-friendly tasks that can contribute to cost savings.
  • Obtaining multiple quotes from reputable contractors allows you to compare prices and negotiate favorable terms. However, it’s crucial to prioritize quality and reliability over low cost when selecting contractors to ensure satisfactory outcomes.
  • Planning and budgeting meticulously from the outset can help avoid overspending and unexpected expenses. Setting aside a contingency fund for unforeseen costs provides financial flexibility and peace of mind throughout the project’s duration.

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 ( 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:

What is GreatBuildz? We Make It Easy To Find a Great Contractor

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.

How can we help with your project?

Explore More Remodeling Topics

Remodeling Cost Guides

Cost Guides

design ideas

Design Ideas

Finding a Contractor

Finding a Contractor

Picking Materials

Selecting Materials

remodeling advice

Remodeling Advice

room addition project articles

Home Additions

kitchen Remodeling Guidance

Kitchen Remodeling


bathroom remodeling advice

Bathroom Renovations

adu and garage conversion blog topics

ADU Construction

backyard Remodeling Projects

Backyard/ Exterior

general home remodeling resources

Home Remodeling