Changing attic space into living space for hobbies, reading or relaxation is a project the entire family can design together. Evaluate how much space your attic will yield and utilize areas in knee wall space under the eaves to expand storage. Designing space to put away clutter will help keep the bonus room neat and make the space seem larger.
Check the rafter joists and side wall framing of the house to ensure they will support new construction. Enlist the help of an expert builder for this. A bonus room will add a lot of weight to an attic area. Measure the floor area you can allow for the bonus room, a closet and bath area. Leave at least 10 feet of head room at the room's center. Investigate the space and measure to make sure you can carve out an area 9 feet by 12 feet with an 8-foot ceiling, not counting spaces under a slanted ceiling area.
Cut out room for a staircase leading to the area that is at least 4 feet wide. Install framing for the bonus room, closet space and a bath from 2-by-4-inch boards. Utilize space in slanted ceiling areas for storage doors, drawers or cubbyholes. Frame the bathroom to include a large closet and dressing area, if you have room. Enlarge existing windows or frame dormer areas. Check roof areas for needed repairs if you install dormers.
Run electrical wiring for all outlets and light fixtures before you enclose the space with drywall. Insulate the walls with roll fiberglass insulation. Install drywall in all areas of the bonus room. Insulate the ceiling area well. Finish the drywall with joint compound, sand and paint. Install electrical outlets, light fixtures and wood trim or crown molding.
Place bathroom fixtures and hook up all plumbing lines and fittings. Paint the walls with semi-gloss paint. Use semi-gloss paint or high-gloss paint on the wood trim. Hang all interior doors, and install flooring materials. Install baseboards around the perimeter of the bonus room and in the interior of the closet spaces.