Calculating the Cost of Adding a Bathroom

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When adding a bathroom, you will need to establish a budget for what is really a fairly extensive project. In addition to plumping and electrical expenses, you will have to calculate the cost of fixtures and finishes such as floors and walls, and countertops.

Regional Costs

While it is possible to find general cost-per-square-foot averages for bathroom remodeling or room additions, in most cases, these estimates have little relevance to local and regional construction costs. Local costs can vary widely depending on regional labor costs and prices for materials and fixtures. These variations in costs can have a huge impact on the final budget.

The best way to find out regional rough prices for square foot costs is to call several local general contractors and simply ask. By asking at least 3 contractors what they would charge for a basic bathroom addition, you should be able to find out the average cost in your area for this kind of home improvement project. You can also talk to your local large home improvement center and they should be able to provide you with rough estimates for local price per square foot construction costs.

Fixtures and Materials

The fixtures and finish materials you choose to install in your bathroom will have a huge bearing on the final cost. Necessary items such as vanities, bathtubs, sinks, and other fixtures are available in a wide range of prices. Your choices will make the difference between an inexpensive basic bathroom addition and an expensive luxurious bathroom.

If you have an idea of what fixtures and materials you want to use, list these items and begin researching and comparing prices. This will help you when you talk to a potential contractor about the project.


As you begin determining your costs, you will need to allocate costs for each aspect of the project. Generally, there are at least 3 phases to any home addition project.


Planning and preparation for a bathroom addition include consulting with an interior designer, architect, or contractor. Since you will need to submit plans to your local building department, be prepared to pay for design drawings. Preparation also includes any needed demolition work and preparing the home for the building project.


Costs associated with the construction phase include not only labor but also materials and fixtures that will be installed with the bathroom addition. Other construction costs include plumbing and electrical services.


Completion of the bathroom is often an ongoing process throughout the addition. As each step of the addition is completed, it needs to be inspected by the local building inspector for approval. Many homeowners find that while they want to complete much of the work themselves, anything that requires approval by a building inspector might be better accomplished by utilizing the services of a professional plumber, electrician or contractor. This can prevent frustrating delays due to inexperience or lack of knowledge and ensures that the building inspector will approve the completed work.

While there is no standard calculation for determining estimated costs associated with adding a bathroom to an existing home, taking into consideration the various costs can be helpful in determining whether or not to embark on this home improvement project.