Bathroom Addition Cost

How Much Does a Bathroom Addition Cost?

Low: DIY Materials Start $500-$1,500

Medium: Simple Conversion Starts $3,000-$6,000

High: Adding Floor space Can Run $25,000-$50,000+

A bathroom addition can range from a small half-bath (sink, toilet and mirror) to a spa-like master bath. Adding a bathroom is usually more expensive per square foot than other rooms because it requires specific types of plumbing, heating, electricity and ventilation.

Typical costs:

Converting existing floor space inside a garage, basement or attic into a simple bathroom starts around $3,000 -$6,000. However, costs can be $7,000 -$25,000 or more for a more luxurious bathroom, or if the new bathroom is far from existing water and sewer lines. Prices may vary significantly by region, depending on local labor rates.
Costs for do-it-yourself materials start around $500 -$1,500, but can run $2,000 -$5,000 or more depending on room size, the quality of fixtures and other amenities. A Pennsylvania homeowner added a 4x8-foot powder room with granite and upgraded fixtures for about $5,000, doing all the work himself except the rough-in plumbing.
Adding new floor space to your home for a basic 6x8-foot bathroom addition starts around $25,000 -$50,000 and goes up depending on complexity, quality of fixtures, number of amenities and local labor rates. RemodelingOnline pegs the price of a 6x8-foot bathroom addition at an average of $36,000 in the Midwest, $36,700 along the East Coast and $40,000 in the Western states. For a spa-quality 10x12-foot master bath the survey says it averages $73,145 nationwide. These prices are all-inclusive for projects using good- to high-quality materials, with work performed by a skilled and licensed remodeling company.

What should be included:

If you're adding new floor space, before you do anything else check with your local planning department. Better Homes and Gardens provides an overview of legal remodeling requirements.
As a general rule, a half-bath should be at least 3-4 feet wide and 6-8 feet long, or at least 18 square feet; a bathroom with shower should be 30 square feet or more; and a bath with both a shower and tub should be at least 35 square feet. ThisOldHouse.com explains how to plan a half-bath (also called a bonus bath) while RemodeOrMove.com lists things to consider for any size bathroom addition.

Additional costs:

Adding a tile floor, marble counter tops, or other upscale features can dramatically increase the weight load on your foundation. You might need to consult with a structural engineer (anywhere from $300 -$800 or more, depending on what's needed and rates in your area) to see if the foundation needs to be reinforced.
Hiring an architect to create a set of plan drawings could cost you a flat fee of $700 -$30,000 or more, depending on size and complexity, or the architect may charge 5-15 percent of the project's costs.
Usually a bathroom addition will trigger a reassessment of your property taxes and a resulting tax increase, but in most areas the reassessment will only be on the value of the addition, not the entire house.
Bathroom design books cost $10 -$40 or more, and can give you great ideas and tips; they may also be available at your local library.

Shopping for a bathroom addition:

Gather photos of bathroom styles and details that appeal to you. Better Homes and Gardens displays a slide show of contemporary styles and Kasmar Publications posts pictures of luxury bathrooms.
Even if you want to do some of the work yourself, most experts recommend hiring a licensed and certified plumber. Ask family or friends for recommendations, or search for referrals from the Plumbing-Heating-Cooling Contractors Association and the National Electrical Contractors Association.
If you want a remodeling contractor to handle all aspects of your bathroom addition, the National Association for the Remodeling Industry provides an online booklet with tips for hiring a contractors, as well as contractor referrals.
Check whether a contractor is licensed in your state, and if there are any complaints with the Better Business Bureau. A written contract should include a detailed outline of the work required and materials used, dates within which the project will be done, and a payment schedule.