How Much Does It Cost to Add a Half Bathroom? [2025 Data]

Size of Half Bathroom

Like many home projects, the size of your addition is directly related to your total project cost. However, unlike larger-scale projects like replacing a roof or changing the flooring in your whole house, adding a half bath won’t really benefit from an economy of scale. Ultimately, you’re just not purchasing enough materials to satisfy the requirement for bulk discounts.

Here is a look at the average cost to add a half bathroom based on square footage.

Professional Costs

If you don’t choose to go with a home addition company near you, there are pros you need to pay. Each one has a different rate and like most things, the more specialized they are, the more they will cost. Below is a list of common professionals needed for a half-bath addition.

Electrician Costs

Hiring a professional electrician is necessary when you add a half bathroom, since the project involves specific skills that the typical homeowner doesn’t have. Common costs include:

• Installing an outlet: $130–$300

• Adding a lightswitch: $60–$300

• Adding a light fixture: $180–$400

• Rewiring existing electrical: $600–$1,800

Plumber Costs

You’ll also need a plumber for this project. Make sure they are certified and you double-check where to place the toilet and sink as these are often expensive to change later. Common costs include:

• Installing a sink: $220–$650

• Replacing pipes: $1,600–$11,600

• Rough-in plumbing for a bathroom: $2,400–$18,000

Architect Costs

Those without planning skills should hire an architect. Architects often charge a percentage of the total project cost, around 8% to 15%. Hourly rates will amount to $90 to $160 or more. Investing in the cost of hiring an architect is wise in order to save money down the line and you may be surprised with a design you wouldn’t have thought of yourself. 

General Contractor Cost 

Working with a general contractor will cost homeowners 15% to 25% of the project cost. While this seems steeper than piecemealing work to separate pros, consider that a general contractor has unilateral control over the entire project. This ensures an even quality of work, and if there are any problems down the line, there is only one pro you need to work with—the general contractor. 

Additional Cost Factors

Adding a half bath can have some unwelcome additions to your project’s bottom line. While there are some ways to avoid the two examples below, 90% of homeowners will need to consider them when pricing out—and completing—their half-bath addition.  

Demolition and Prep

If you’re taking space off of your living room to accommodate a half bath, you don’t need to do any demo. However, if you decide to significantly alter your home’s layout, expect the price to rise as permits need to be pulled and the cost of planning balloons. You can’t prep much for this job other than removing flooring and any electrical or existing plumbing—don’t do this yourself—so you need to hire a pro for pretty much anything beyond taping out the area or knocking out some drywall. 

Permits

You’ll likely need a building permit to build a half bathroom. The price of such a permit depends on your municipality, but expect to pay between $125 and $600. If you’re working with a local bathroom remodeler, they will be able to help you through the permit process. However, they will file and secure it themselves as part of your project cost.  

Accessories or Special Features

Half baths have the luxury of being more sparsely furnished than the main bathroom of a house. Many homeowners choose less expensive options because a half bath is often one of convenience, not style. Here are the average costs of some common half-bathroom features.

DIY Adding a Half Bathroom vs. Hiring a Pro 

If you choose to DIY a half-bath addition, you’ll save around 30% of the total project cost in labor, not taking into account your own time value. While this may sound appealing, we recommend combining DIY work with the use of a general contractor, thus lowering the time it takes for the addition.

You don’t want to attempt any plumbing or electrical work because it can cause serious damage if done incorrectly. However, you can work alongside a general contractor doing some of the more simple work, like tightening screws, painting, or laying down laminate. 

Once you have a proposal for work outlined, discuss with your general contractor what you can do yourself to cut down on costs. 

Tips to Reduce Costs While Adding a Half Bathroom 

When building a half bath, you should focus money-saving efforts on materials—not labor. Some ways you can save are:

• Perform the time-intensive but low-skill labor yourself (like painting). 

• Check salvage stores for used or unused fixtures like sinks and toilets. 

• Sign up for home improvement store discount emails. 

• Talk to your contractor about where you can cut costs in materials. 

• Reuse any old plumbing you might have if it’s still in good working order. 

• Use energy-efficient fixtures (toilets, sinks, lights). 

• Consider budget alternatives to expensive materials like marble and steel. 

Does Adding a Half Bathroom Increase Home Value? 

Adding a half bathroom increases a home’s financial value by about 6%. Depending on the size of your home and the number of bathrooms you already have, this number can fluctuate quite a bit. 

A larger home with five full bathrooms will not see a 6% increase in their home’s value by adding a half bath—more like 2% or even less. Flip the coin and consider a small house with only one bathroom. Adding a half bath to a smaller property can easily increase the home’s value over the 6% average.

Beyond finances, a half bathroom adds quality of life value to a home. In the above example, a half bathroom in the large house may be used next to a mud room, saving the occupant from having to walk upstairs or across the house. A half bathroom in a small house with one bathroom means there are two available toilets, eliminating trading turns for a single bathroom.

Finally, a half-bathroom addition will appeal greatly to buyers looking for more than one toilet and sink in a property and can generate increased interest during a sale.