Without putting on an addition, you can easily make a garage apartment out of your unused space. Before you begin any construction, check with your local zoning ordinance in case you need any permits to change your existing garage into a livable room. Here are some factors to consider as you get your project underway.
A garage apartment will need to have at least four electrical outlets and perhaps separate plumbing from the main house. Luckily, most garages are built with these features already in place. Depending on your design, you may need to move some outlets or add on some plumbing. If you need to put in a kitchenette or a bathroom, it may require some major construction.
The easiest way to add a new apartment is to make sure it meets the same homestyle requirements as your existing house. This means that the walls should be sheet-rocked, textured, and painted. The concrete slab will need some treatment too, so it is crucial to plan out every detail of the new room before you start construction.
Changes to the overall design can severely impact the total cost.
Part of your plan should include a sheetrocked framed wall that covers the existing garage door opening. The garage door should be fixed in a shut position and may need to be screwed into place to prevent opening from the outside.
The slab needs to be completely clean. This may mean using a mild acid wash or garage floor cleaner. These are obtainable at any home supply center.
If you already have drywall in place, wipe down the walls with a weak mixture of T.S.P. (trisodium phosphate).
Install baseboards as necessary. These should be caulked to the wall and the floor with a good grade paintable caulk.
This is the first big step. Always start interior construction from the top down. Paint the ceiling, then the walls. It is a very good idea to rent an airless high-pressure paint sprayer to do this, as this can cut your painting time down by at least 2/3. Do all of your wall painting prior to installing any type of flooring.
Garage apartments are typically floored with ceramic or vinyl tile as the "leak" factor inherently built into garages meant to store cars is not great for wall-to-wall carpeting. Probably the best surface is epoxy, which can be covered with area rugs as necessary.
After painting the walls and ceiling, it is recommended to once again really clean the floor well before you install any sort of finished surface. You may need to use a weak acid wash to etch the concrete pad if you have too much paint build up.
In most cases, your garage will have an electrical receptacle in the ceiling. This makes it very easy to install a ceiling fan with lights or just a light fixture. Floor lamps are also very handy to use around the perimeter of the room.