DIY Room Addition Price Estimating

Home additions can help rejuvenate the appearance of a home, as well as provide much-needed extra space. Whether you are adding a bathroom, bedroom, living room or an entire second floor, additions can provide a great alternative to finding a new home. Before constructing an addition as a do-it-yourself project, it is important to lay down on paper the precise location of where the addition will be, as well as its dimensions. Then, you will be ready to estimate how much the project will cost.

Adding a Bathroom

There are two options for adding another bathroom to your home. You can either convert an existing floor space, or build an entirely new room. According to CostHelper.com, do-it-yourselfers may only need to spend as a little as $500 on parts to convert a space into a bathroom, but more high-end bathrooms (with jet tubs and all the amenities) can cost as much as $4,000. According to the above source, the cost of adding an entirely new floor space for a bathroom will start at $25,000.

Adding a Bedroom

According to CostHelper.com, for do-it-yourselfers adding a standard 10-by-15 bedroom, the cost will likely be between $3,750 and $7,500. However, this does not cover electrical work or furniture.

Adding Living Room

The cost of adding a living room or lounge on to your home will vary with the room's size. According to CostHelper.com, a 400-square-foot room (with the dimensions 20-by-20, for example) will typically cost between $10,000 and $20,000.

Adding a Second Floor

Poorly constructed second floors added on to houses are more likely to cause serious harm than poorly constructed ground-level room additions. Add a second floor as a do-it-yourself project only if you have extensive construction and/or carpentry experience. According to CostHelper.com, adding a 1,500-square-foot second floor -- with multiple rooms - on to your home will likely cost between $100,000 and $225,000.


Whenever you add a room or something else of value to your home (such as a swimming pool), your city or town government will usually reassess your property taxes (typically, they will increase). According to CostHelper.com, in most places only the value of the addition will be reassessed, and not your entire home.


In addition to considering the immediate costs of constructing an addition, you must also think to the future. Over the long run, additions -- especially large ones -- will cause your monthly heating/cooling bill to rise. Your electricity bill is also likely to rise, especially if you add on a living room with a home entertainment center and other electronics.

About the Author

Lauren Treadwell studied finance at Western Governors University and is an associate of the National Association of Personal Financial Advisors. Treadwell provides content to a number of prominent organizations, including Wise Bread, FindLaw and Discover Financial. As a high school student, she offered financial literacy lessons to fellow students.