Home Blog What Is the Cost of Adding A Half Bathroom?

What Is the Cost of Adding A Half Bathroom?


So, you need a little extra bathroom space and you have settled on the half bathroom option to save some coins. So, how much will it cost you to add a half bathroom?

Unless you live alone or you live in a house with enough bathrooms to cater to several people at the same time, additional bathroom space makes life a lot easier for large families.

A half bath consists of a toilet, a mirror, and a sink. You can pimp it out more by adding some extra storage space and some aesthetic vanity to match your taste and trends. A sizeable half bathroom is about 3-4 feet wide and 6-8 feet long.

Costs for adding a half bathroom are widely varied and depend mostly on the location of the bathroom and its design. For example, converting an existing space into a bathroom is more affordable compared to building a new addition. 

To add a half bathroom to an existing space, you may need anywhere between $5,000 and $15,000 but if you are building an extension, the cost goes up to anywhere between $10,000 and $30,000.

The cost of turning a bedroom into a half bathroom should cost you anywhere between $7,000 to $12,000 on average.

However, there are a few factors to consider such as the size of the space available which affects the expenses towards flooring, amenities, ties, and remodeling.

Another factor to consider is the distance the room is from the drains and plumbing because it will cost more to run new plumbing lines.

Converting a laundry room into a half bathroom will set you back about $5,000. The cost is much lower here because plumbing is pre-existing and only some minor adjustments need to be made.

Depending on the level of finishing done to an attic, if you want to change it into a half bath, prepare to part with about $15,000.

If the attic is finished, all that is needed is for the part needing installation to be enclosed off. If the attic is unfinished, budget for the bath, insulation, drywall finishing, and painting.

If you have a lot of unused space in your garage, adding a half bathroom to it should be fairly manageable because there are more options for design because of spacing and the electrical and plumbing lines should be flowing from here. It could cost you about $8,000.

A table detailing the costs of adding a half bathroom

Installation Tasks
Average Cost Range
$1,000 – $10,000
$500 – $2500
$200 – $550
$1,000 – $2,500
$1,500 – $4.500
$500 – $3,800
$150 – $350
Lighting Fixture
$150 – $900
Towel Rack
$20 – $100
$400 – $3,000
$50 – $2,000


Closet conversions into half baths will cost you About $5,000 based on the size and the distance of the closet from available plumbing and drainage. These tiny spaces do not spend on extras such as storage cabinets, vanities, or tiled showers.

If you have no space for your proposed half bathroom, you will have to build a bathroom extension which will cost you at least $20,000 to get done. 

These costs only cover the bathroom installation and you will need to dip further into your pockets to cater for foundation costs if you plan to extend it into your yard space which costs anywhere between $4 and $7 per square foot.

A more affordable option for those considering an extension is to do a dormer installation which is a vertical extension stemming from your house’s attic. This could cost you as little as $2,500 considering the ease of access to the electric and plumbing lines.

The cost of plumbing a bathroom will take a large part of your budget especially if you plan to position it somewhere far from the plumbing. However, sometimes even when the plumbing is close enough, it isn’t large enough to support the addition of lines and this calls for new lines to be run from the main.

Based on the extent of plumbing work needing to be done it would set you back anywhere from $1,000 to $10,000.

Another big expense you will come across as you convert spaces into a half bathroom is the electrical cabling. Just like with the plumbing lines, it will save you some cash if you could add a bathroom close to existing circuits.

Taking into consideration all costs including breaker panel upgrades, electrical panels, and wiring, switches, outlets, and lighting, the total will range between 1,000 to 8,000.

Installing the toilet ranges between $300 to $500 depending on your supplier and a sink will be about $600 to $1,200 

Bathrooms will need waterproof and resilient flooring and it installing it will cost $1,500 to $4,500. Tiled flooring costs $900 to $2,600 on average. Other flooring options are such as bamboo, engineered hardwood, or vinyl.

You will need permits to do all these changes to your house and the regulations vary from state to state. If you intend to change the existing floor plan, add new doors or windows, installing and rerouting ductwork or make changes to electricity and plumbing, you will need to get a permit.

You should know that adding a half bathroom to your house will increase your house value by 10% if you intend to sell it in the future.


To add a 6 x 8-foot-long half-bathroom, it will cost you about $124 per square foot. With additional costs of plumbing electric routing and finishing, the total most approximate cost for the entire process will be about $47,000.


Can I install a half bathroom anywhere in my house?

Yes, technically it is possible. However, for best results, a waste pipe needs to be run through which puts a limit on your options.

Why do I need a permit to add a half bathroom in my house?

This is because the toilet needs to be hooked to a septic tank which is run by state authorities. It is illegal to make such changes in running construction without notifying your local government administration.



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