Enclosing a home's breezeway is easier than building an addition because the breezeway is already under a roof. This space typically stands between a house and a garage. The roof over the breezeway is designed to literally channel a breeze. When homeowners sit in the breezeway area, circulating air keeps everyone cool. Blocking in the space will provide ample space for a small den or office, for example. It typically will not include enough floor space for a large bedroom. By knocking out a wall, however, you can incorporate the breezeway into an existing kitchen or living room.
Examine the breezeway's construction for building options. Make sure the breezeway foundation is sound, for example, if you will construct a room over it. Replace a wooden decking over breezeway space with a concrete slab, as one option. Enclose the breezeway as a screened room if you don't want to replace wood floor decking. Consider enclosing the area as a sunroom with two walls of glass, as another possibility.
Use as much natural light as possible. Build in a bright, sunny room by enclosing both ends with walls made of french doors, for example. Plan to vault the interior ceiling and install a couple of skylights to allow even more light inside the space. Design the side walls which face the garage and the house to expand the space. Plan to drywall the solid walls and paint them white, for example.
Build flooring appropriately and frame the space with studs. Construct a solid concrete floor, for example, and use 2-inch by 4-inch boards to enclose each open end of the breezeway. Install an opening going directly into the garage, if you wish, or cut an opening into an adjoining living room.
Install exterior materials and add windows or french door walls. Construct the space similar to a three-season porch. Be sure to insulate the upper rafters of the space extremely well so that heating and cool air won't escape. Run electrical wiring inside the space before nailing up drywall material.
Finish the details and install flooring. Paint all drywall walls, and install crown molding in the new room, for example. Hook up electrical outlets and light fixtures. Lay tile flooring or hardwood in the space last so the floor won't get dents or nicks during construction. Paint baseboard materials before nailing it in place so you won't have to paint it on your knees.