How to Build a Room Above a Garage

Contact your local building authority. You may need to take out a permit to remodel the area above your garage, especially if you change the structure, which is a distinct possibility.

Beef-up the garage ceiling. If the garage was not constructed to support the weight of a floor, you must reinforce the joists, bringing them up to code before continuing. Many garage ceilings use a wide lumber span with no support. In addition to adding to the joist strength, you may have to put a lead-bearing wall (or columns) in between the garage stalls beneath to support the weight.

Figure out where you will put the stairway. If you keep it inside the garage - you will lose space. For that reason, many garage apartments feature outside stairways and entrances.

Consider plumbing and mechanical fixtures. Unlike a house, most garages are not equipped with plumbing. How far will you have to go to bring the utilities to the garage? This can be a substantial expenditure. In addition, consider putting a sealed HVAC unit in the room, ducting to an existing house heat and air unit is probably out of the question.

Abide by fire safety codes. There are a couple of big red flags when building a room over the garage. First, there is usually only one entrance and exit, so purchase and learn how to use a roll-out window ladder in case of fire. Secondly, if anyone lives or sleeps in the room, you may be required to remove all flamable substances stored below in the garage. In some communities, you must construct a firewall between the garage and the upstairs room.

Install windows on the gable ends or install skylights to allow natural lighting to enter the room. If dormers already exist, you can use those for windows.

Finish out the room above the garage just as you would any other inside living space but minimize excess weight. It's probably not a good idea to install a stone fireplace in the room or to furnish it with a heavy waterbed.