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The Home Depot

How Much Does a Room Addition Cost?

Pro Referral > Home Guides > General Contracting > How Much Does a Room Addition Cost?
How Much Does a Room Addition Cost?

Adding a room to your home can provide needed space without requiring a move for your family. A number of addition types carry specific construction issues, and different building scenarios may affect project prices. Your architect and contractor can help you plan a room addition that meets your needs and integrates effectively with your existing house.


Average Room Addition Cost

The cost guide below provides average prices to add an additional room in your home.

Average Prices

Level of Room Additions

Ground level additions are popular, and can usually be incorporated smoothly with the structure of your existing home. Prices for ground level additions range with their size and foundation type, but typically cost an average of $32614 in the U.S. A second story addition provides options for expansion without increasing the footprint of your home, but requires raising or rebuilding your roof to provide a second living level and costs around $45802. Detached additions are growing in popularity around the country, with prices varying with the size and features of the structure. With an average price of $22814, detached additions can add space to your home in unconventional ways.


Addition Size

Many construction tasks are priced according to square footage, and while many aspects of your project will be priced according to their specifications, the overall size of your addition can help indicate total costs. Small builds of 200-300 square feet average $24608 in the U.S. Increased material and labor costs for larger additions bring prices of $39207 for a 300-400 square foot project, $55350 for 400-500 square feet, $66284 for 500-600 square feet, $84506 for 600-700 square feet, $90752 for 700-800 square feet and $112672 for additions of 800-1,000 square feet.


Architectural Drawings

Architectural drawings provide important construction details for a project, but in most cases are not required to acquire a building permit for a room addition, or to complete construction. Having your addition built without drawings may cost $46171 on average, and requires your builder to prepare his own plans. Providing architectural drawings to your contractor can simplify planning, pricing, and executing construction. The use of drawing impacts overall project prices, with a national average of $58043 to complete an addition.


Building Permits

Building permits are required for room additions, and are granted by the municipality in which construction takes place. The process of securing a permit involves submitting an application and paying a fee, then awaiting approval for your project. With permits secured, construction on your room addition can begin without delay, costing an average of $38942 overall. Without permits in place, fines, suspensions and other setbacks can delay construction and increase costs, resulting in average prices of $45116. Discuss the permit process with your contractor to ensure your application is in order and that permits are secured before construction begins.


Pricing Materials

Room addition projects for which contractors include materials in their pricing cost an average of $39157. Contract pricing is often used when the parameters and scale of the project are clear, and usually includes buffers to ensure flexibility for changes or complications that may arise during construction. Your contractor may choose to price your materials on a “cost plus” basis instead, providing them as needed while the job progresses. Cost-plus pricing helps maintain a standard of quality while covering all expenses, and may be used on projects with incomplete designs, unclear scope, or when several contractors overlap. Using cost-plus pricing for materials typically averages $22057 for total room construction costs.


Types of Room Additions

Special considerations for different types of additions affect construction and finishing costs. In addition to framing and exterior components, most rooms have several common requirements such as insulation, drywall, electrical, HVAC, and flooring. These elements combine for average addition prices of $24322 for bedrooms, $40237 for living and family rooms, $18643 for lofts, and $21774 for office space. The added plumbing and ventilation requirements of some rooms contribute to average prices of $22071 for bathrooms, $19158 for laundry rooms, and $58743 for kitchens. Other additions may have minimal finish and fixture requirements that affect construction prices, such as garages, which cost about $42901, and sun rooms and screen rooms, which carry installation rates of about $24513 and $16047, respectively.


Planning for a Room Addition

Adding a new space to your house is a substantial project that involves several aspects of home construction. Regardless of the type and size of addition built for your home, several important factors affect the difficulty and expense of the project. Be sure to discuss with your contractor how the characteristics of your addition and its integration with your home affect the complexity and cost of the project.


Room Addition Contractors

If you are ready to line up a Pro for a room addition project, submit a work request for adding a room in your area to discuss the job. All of the Pros in our network have been background checked and our in-house staff has verified their credentials and insurance coverage. Hiring a trusted Pro can give you the assurance the job will be done right, every step of the way.

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