Turning a garage into a room is a tempting remodel for many homeowners. Because the garage already has a foundation, floor and roof, converting it to living space can be far less expensive than building an addition. If the yard is small, a garage conversion is the only way to expand a house without building up. In general, a two-car garage can add a good 600 square feet of living space. Like any remodeling project, the cost factors to convert a garage are extremely variable, depending on adding insulation, plumbing, flooring and windows as well as labor and building permit fees.
Average costs for conversion
A general contractor, such as Corniel Construction in North Bergen, New Jersey, Marshall Home Pros in Old Orchard Beach, Maine, or Lange Design and Development in Sutton, Massachusetts, is the best type of service provider for a garage conversion project.
There’s no single formula for figuring the costs of turning a garage into living space. To make it livable, the garage door must be replaced with an exterior wall, insulation must be added inside the drywall, the floor must be made level with the rest of the house, and the entire space must be finished.
Depending on the type of room being added—bedroom or living room—and whether a bathroom is included, the cost can range from as little as $6,000 to as much as $50,000. The U.S. average for such a project is about $10,000-$15,000. The cost of the contractor contributes greatly to the cost variability, depending on whether they charge a flat fee of 10 percent to 20 percent of the final project cost or an hourly rate. Adding a bathroom can increase the total cost by $15,000-$25,000.
Garage conversion permits
Most cities require the homeowner to secure a building permit for this project, then prove the room has been built according to code. On average, this costs between $1,000 and $1,500. Note that some cities, like San Mateo, California, do not allow garage conversions; building one illegally will drag down the value of the home.
Interior garage changes
Turning a garage into a room requires adding a ceiling with insulation and building interior walls. This generally costs between $1,700 and $2,000, plus insulation at $1-$2 per square foot. Windows, which are required by law, cost about $1,000 each. Because the space must be comfortable, the HVAC system must be extended to the garage; installing ducts and vents ranges from $500 to $2,000. Most garages are already wired, but a converted garage needs outlets in useful places; adding sufficient wiring and outlets for a room costs between $75 and $500.