How Much Does It Cost to Add a Half Bathroom?

Bathroom Addition Cost by Project Range


48 sq.ft. full bathroom conversion in an existing space with no new plumbing lines or modifications

Average Cost

48 sq.ft. full bathroom in a new space addition

High $60,000 100 sq.ft. master bathroom addition in a new space


Question: Does adding a bathroom increase taxes?

Answer: Adding more square footage to your house will increase its value. But doing so will increase the taxes as well. However, the good news is the owner will be the one to pay them.

Question: How much time is needed to install a new bathroom?

Answer: The time needed for installing a bathroom depends on its size. Building a big master bath can take 3-4 weeks of time. For small and half-baths it takes around 5-7 days for full installation.

Question: How to add a bathroom with an existing bathroom?

Answer: Adding a bathroom with an existing bathroom is done by attaching the plumbing line. Since the plumbing line already exists with the old one you can use that. Doing this will reduce the plumbing cost greatly.


What to Consider Before Adding a Bathroom

Adding a bathroom to your home can be a great decision for you, both in terms of your comfort and financial value. However, it is important to put thought into the project before embarking on a home-improvement project. In order to maximize your home value and comfort as well as reduce costs, factors such as size, location and quality need to be taken into account.

In terms of size, the question of whether to build a half bath or full bath should come first. Determining what kind of space you have to work with is important. While bathrooms do not require a large amount of space, using space efficiently can make a huge difference in building a navigable, useful bathroom that does not feel cramped. Putting extra effort into the layout of the sink, toilet and shower can save you money when it comes to building and plumbing.

Another point of consideration is the number of bathrooms you already have in your home. If you wind up having significantly more bathrooms than bedrooms, the addition of each subsequent bathroom will increase the value of your home by less, making the investment less worth your while. 

Where to Place Your Bathroom in Your Home

Determining where to build your bathroom is also crucial. A poorly placed bathroom not only causes you inconvenience, but it makes your home less valuable, costing you financially. Using an existing, unused space in your home can help cut costs.

Closets, especially walk-in closets, can easily be converted into bathrooms. A storage space at the end of a hallway makes for a great bathroom or powder room for guests. You can also divide a large bathroom into two smaller bathrooms relatively easily, which can give you more privacy and, likewise, increase the value of your home.

Partitioning space off from a larger bedroom, such as the master bedroom, can also make space for a private bathroom. Adding a bathroom to a bedroom can allow more privacy, which increases home value as well as your quality of life. 

Features to Include in Your Bathroom

The amount that your bathroom increases your home value will depend significantly on the features you choose to include in your newly-built bathroom. Stone sink countertops are usually ideal for bathrooms, and standard chrome faucets work for an average bathroom.For a Nicer Bathrooms:

  • Consider investing in a double-sink with custom faucet and handles
  • Match the floor and the wall tile to ensure the design looks cohesive and upscale
  • Include a tub as well as a shower to elevate the bathroom

For More Modest Bathrooms:

  • Choose more affordable materials such as fiberglass for tubs and showers
  • Spend less on tile
  • Be open to alternatives to full bathrooms that may be more space-efficient

3 Half Bathroom Layout Ideas

1. Tucked Under Stairs

This option makes use of an area that’s frequently underutilized. For privacy’s sake, it works best in homes with an enclosed foyer that opens into adjacent entertaining spaces. The two biggest obstacles are providing ample headroom and ventilation.

I recommend a minimum height of 5 feet above the toilet; check your local codes for height requirements and an exhaust vent will need to be run to the exterior. Place the sink or vanity on the tallest wall so hand washers won’t bump their heads.

2. Carved Out of a Garage

In this example, we were able to slice out a portion of the tool room in a client’s garage to create a half bath that serves the adjacent kitchen as well as the garage and outdoor areas of the home.

Because of the number of doors in the home’s rear entry, access to the half bath is via a sliding pocket door, which solves the problem of doors banging into one another or unintended “door traps” that result when doors are left open.

3. Fitted Within a Dormer

This is a good option for houses that have a decorative gabled dormer on the attic level. If the ceiling heights within the dormer are at least 7 feet at the interior ridge, and if there’s at least 5 or 6 feet of width between walls at least 5 feet tall, you’ll have room for a half bath.

If the dormer is at least 5 feet long you can even add a bathtub; in this example I put in a tub and added a shed dormer above to bring in natural light.

Half Bath Dimensions

Photo by Peter Johnston, Architect, PC

A half bath needn’t be large. You will have enough space if you can find a spot in your house that’s about 3 to 4 feet wide and 6 to 8 feet long. If it’s any smaller, it will be uncomfortable for people to access. A larger half bath is unnecessary, and it’s not likely that you’d find that much “extra” unused space in your house.

Shown: This parlor bath in New Jersey is able to capture a hotel spa look in a limited space of 40 square feet.

Places in Your Home Where You Can Add a Half Bathroom

Still pondering the best spot in your home to add a half bathroom? If you can convert an existing room, closet, or the laundry room, you’ll likely save a bundle. Otherwise, you can consider adding a half bath in the hallway near the front of the home, beneath the staircase, in the game room, basement, or garage.

What Is Worth More, a Bedroom or Bathroom?

If you are wondering whether to add a bedroom or a bathroom to your home from a resale value or wondering if you should keep a bedroom or convert it into a bathroom, there are several things to consider. First, bathroom additions get a slightly higher ROI than bedroom additions. Bedroom additions typically cost more simply because they are larger, so a bedroom addition may add more monetary value while the percentage is slightly higher for a bathroom.

The second thing to consider is the ratio of bedrooms to bathrooms in the house. It is generally recommended you have two bathrooms for every three bedrooms. If you have one bathroom and three bedrooms, adding a bathroom or converting one has more value. However, adding another bedroom to the home has the most value if you have two bedrooms and four bathrooms.

See the range for bathroom and bedroom additions below.

AdditionAverage Costs (Labor Included)Bathroom$15,

AdditionAverage Costs (Labor Included)
Bathroom$15,000 – $40,000
Bedroom$37,000 – $100,000

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Frequently Asked Questions

Taking on a bathroom remodel or installation uses a lot of different trades and features that can all add up quickly. Getting a solid estimate beforehand will help you stay in your budget. P1020251.JPG by Brad Cerenzia / CC BY 2.0

1. What is the most cost-effective way to add a bathroom to your home?

The most cost-effective way to control your average cost to add a bathroom is to put it in an existing space. It’ll already have electrical, plumbing, and HVAC installed. The laundry room and basement are the two cheapest areas in your home. 

2. Can a toilet go anywhere in your home?

Technically, you can put a toilet anywhere in your home. However, you’ll have to run a waste pipe from it, and you’ll need a stackline for every toilet at a minimum. This can limit your options. 

3. Is it possible to add a bathroom to a house with a concrete slab foundation?

Yes, you can add a bathroom to your home if it has a concrete slab foundation. However, this can cost more because your contractor will have to think outside of the box to run new sewer and water lines. This can also make the install go on longer. 

4. What is the average cost to add a bathroom if it’s a master suite with a bedroom?

If you want to add a full master suite onto your existing home, this can be an expensive project. You’ll pay between $21,500 and $65,000 to complete it, and this is the national average. 

What are the Benefits of adding a Half Bathroom?

Installing a half bathroom in your home will ultimately increase the value of your home. On average, installing a half bath will add 10% to your home’s value.

This bathroom also provides a convenient and easy to access bathroom for guests and family members. Since it is a half bath, it is much easier to clean and maintain than a larger bathroom as there is only a toilet and a sink. 

Bathroom Type and Pricing

The average cost to add a bathroom will fluctuate depending on the type of bathroom you want to install. For example, choosing to add a small half bath will cost around 50% less than it would if you wanted to install a full bathroom, unless you went for luxury. 

  • Half Bath – The average cost to add a bathroom of this type is around $12,000 for 12-square feet. You only need a sink, toilet, and a mirror. It can include a linen closet or cabinet for storage, but you have a very small space to work with. 
  • Three-Quarters Bath – The average cost to add a bathroom that is around 36-square feet is $35,000. You get slightly more space, and it usually has enough room to accommodate a stall shower, mirror, sink, and a toilet. You could also have a closet or cabinet for storage space. 
  • Full Bath – For 48-square feet, the cost to add a bathroom in this style is right around $41,000. You’ll add a mirror, sink, toilet, and a separate shower and tub or a tub/shower combination. It has space for several cabinets or storage shelves, and you can put in a linen closet without making it cramped. 

There are three main bathroom types you can choose from, and your budget will play a large role in the one you end up with because the prices are broad. 570 Wake Robin Bathroom Upstairs by John Coley / CC BY 2.0

Average Cost To Add A Bathroom

Overall you should be able to add a simple bathroom for as low as $2,500 by remodeling existing space or about $22,000 for a new addition. No matter where in the home you are adding a bathroom, the cost will mainly depend on whether you are using existing space within the home or building onto the house. [1]

Cost To Add Bathroom To Existing Space

The average homeowner spends about $7,600 for turning existing space into an 80–100 square foot bathroom. [2] Whether you’re adding a bathroom in the back of the house to use as a mudroom, or in the master bedroom to use as an en-suite bathroom, additional bathrooms add to your home’s value and increase convenience. If you spend $47,400 on an upscale bathroom remodel, it will increase add value to your home by about $28,700. [3]

Cost To Add Bathroom To A Basement

Adding a new basement bathroom costs up to $15,200 for a 6×8 powder room with 8-foot high ceilings. Plumbing labor fees add $720 to $1,350 for setting up a new sewage-ejector system that moves your waste water up and out of the basement area. Most costs for other bathroom fixtures in a basement are about the same as in other bathrooms.

Bathroom Addition Cost Estimator

New Bathroom Installation Costs
Fixture Installed Average Lowest to Highest
Shower/Tub $500–$1,000 $400–$3,900
Tile $4–$7/SF $4–$9/SF
Toilet $250–$400 $270–$3,200
Sink/Vanity $180–$550 $200–$4,600
Flooring $4–$8/SF $2–$100/SF
Plumbing $800 $600–$1,200
Electrical Work $500 $350–$700

Bathroom Addition Cost Factors

Bathroom Addition Cost Factors

Many variables affect how much your bathroom addition will cost such as:

  • Location – If the new bathroom is near existing plumbing, it will cost less than if you need to bring plumbing, vents, and waste lines to the new bathroom.
  • Size – Will you need to knock out walls to make room for the new bathroom or will it go into an unused walk-in closet? Most bathroom additions are inside the home, meaning you won’t have to build out a foundation or add a roof to it.
  • Scale – Will this be a practical bathroom or a luxe addition to the master bedroom?
  • Age of your home – Will the plumbing or electrical work need to be updated before the addition can proceed?
  • DesignArchitect hourly rates are $100 to $250 per hour to design the bathroom.
  • The unknown – Once you begin opening walls and looking into attics, crawlspaces, or basements, you may find some unexpected problems. There could be mold in the walls or a water leak. You might find evidence of pests or asbestos. It’s a good idea to put some extra money in your budget for the unexpected. If you don’t see anything surprising, you can use the extra money to upgrade one of the aspects of your bathroom addition.

Half Bath or Full Bath?

A full bath has a sink, toilet, and shower or tub. Full bathrooms are typically added to the master bedroom or are on another floor beside the main floor. Converting a half bath to a full bath can increase your home’s value by up to 20%.

A half bath only has a sink and toilet. Extra bathrooms are usually found near the front of the home as a place for guests to use the facilities without tromping through your house. Small bathrooms can also be useful in the laundry room, mudroom, or garage/workshop. If you’re working with a small space, consider a three-quarters bath, which is a half bathroom with only a shower.

A half bath should be three to four feet wide, and

A half bath should be three to four feet wide, and six to eight feet long, or around 18 to 30 square feet. According to the National Association of Home Builders, adding a half-bathroom can add 10 percent to your home’s value. The decision to add a full or half bath will come down to a few factors:

  • What is its purpose?
  • Where will it be?

What Do These Costs Include?

Milk and Honey Life

The cost of adding a bathroom may seem steep, but the high price includes quite a few things: your bathroom necessities, flooring, hardware, plumbing, permits, andinstallation. This applies if you're adding a bathroom to an existing space—if you're building out a new addition, you'll have to pay for those additional expenses, like framing, insulation, and drywall, too. With all these costs, it's no surprise that the price tag for a bathroom addition starts in the thousands.

However, one of the easiest ways to cut costs—without cutting corners—is by sourcing less expensive materials. That can mean going for the pre-fabricated bathtub or shower instead of the expensive tile surround, finding a vanity from IKEA, or refurbishing an old one rather than having one custom-built. You can also try to DIY a few things yourself, like installing hardware, painting, or—if you’re feeling adventurous—tiling.

The 6 Best IKEA Bathroom Vanities to Open Up Your Small Bathroom

The Cost of Building a New Space for Your Bathroom Addition

Rebecca Rollins Interiors

Here's the bad news about building an addition for your bathroom: It's expensive. HomeAdvisor estimates that the average cost of a new bathroom addition is $35,000, but that it can cost anywhere from $20,000 to $90,000. But before you give up on your addition entirely, there's good news, too: You won't have to figure out how to awkwardly reconfigure your home around your new bathroom, plus the added square footage gives a major boost to your home's resale value.

If you want to make the most of your bathroom addition, consider using the renovation to add on another space, like a bedroom or multi-purpose room.

Bathroom addition: A real-life example

We reached out to Holmes to get the scoop on a recent real-life bathroom addition. Holmes specializes in ground-up new construction and rehauling existing construction. He kindly provided an example quote for a recent bathroom addition under an existing room. Here’s a breakdown of the major costs and labor, including time and materials:

Bathroom Addition Under Existing Roof Labor Materials (Estimate) Cost
Design & Permits (this included all permitting for the project, as well as architectural designs) $2,700 $2,700
Site Prep $600 $600
Demolition & Temporary Support $1,230 $1,230
Excavation (to prep the area for running the plumbing, electric, & HVAC lines) $1,800 $1,800
Foundation $2,200 $2,200
Framing $3,200 $3,200
Windows & Doors $644 Door: $60

Two Windows: $296

Siding $1,320 $6 per square foot (labor & materials)

220 sq. ft.

Drywall & Paint $1,520 $4 per square foot (labor & materials)

380 sq. ft.

Tile $900 $15 per square foot (labor & materials)

60 sq. ft.

Trim $600 Included with labor $600
Bath Finishes $890 Toilet: $200

Vanity: $500

Sink: $160

Plumbing $3,400 Included materials, plumbing to client purchased bathtub $3,400
Electric $1,300 $1,300
HVAC $2,600 $2,600
TOTAL $26,120

In this project, and in Holmes’ experience working with clients adding bathrooms, many of them aren’t aware how much installing plumbing, electric, and HVAC will drive up their budget.

How Much Does It Cost To Add a Powder Room?

Several factors can determine the cost of adding a powder room to your dwelling. The first thing you need to consider is the size.

Above, we mention that a standard powder room is about 4 feet wide and 8 feet long. However, a larger powder room will be more expensive to construct. 

Next, you need to consider the bathroom’s features. A typical half bathroom needs a toilet, sink, mirror, and running water. You can also add a few storage facilities to keep the room organized. 

The final factor you need to think about is plumbing. Depending on how sophisticated your plumbing system is, it can be the most expensive element of building a powder room.

For a reliable plumbing system, you can expect to spend roughly $10,000 to $20,000.

Here’s a rough breakdown of how much you can expect to spend when adding a powder room to your property:

  • Door – $100 – $200
  • Mirror – $75
  • Toilet – $250
  • Storage – $300 
  • Faucet – $100
  • Labor – $2,000 (depends on the contractor)
  • Fan – $200
  • Flooring – $10 per square foot

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