Things You'll Need
Round-blade electric saw
Stainless-steel flat-head screws
Interior-grade plywood sheets
Set of pull-down stairs
Most garages have enough headroom in the attic to create lots of storage space. By utilizing this space, you can remove clutter from other areas of your home. Seasonal items such as Christmas decorations or winter clothing can be stored there, so this will free space in hallway and bedroom closets. Storage space in an attic garage does not require the insulation or finishing touches of building a room there, so it's relatively inexpensive to build this storage space.
Tap into the attic space over the garage, using a tall A-shaped ladder. Create an access opening or install a pull-down stair unit if you don't have one. Break the drywall or plastic ceiling with a hammer to gain a view of what the space looks like. Don't cut any rafters for an opening yet. Examine the space for water damage or roof leakage and check out all electrical wiring routes or plumbing pipes in this attic area.
Repair the exterior of the garage roof, if needed. Don't construct flooring or finish the garage attic until you make all needed repairs to protect against rain damage. Hire an electrician to disconnect any wiring that will run across the floor area you wish to create for storage. Have electrical wires redirected and install housing for a light fixture if there is none.
Cut one rafter with a hand saw if you need space to crawl into the attic. Never cut a double joist in a garage attic, since double rafters are support beams for the structure itself. Nail an outline of the opening you wish to cut from the attic side of the ceiling. Use nails long enough to come through beside beams you will leave intact. Draw the opening with a carpenter's square. Use a round-blade saw to cut the rafters to create an opening for an access door.
Frame the opening you've cut with lumber boards as deep as the attic rafters. Nail and screw this framing into place to support the attic floor area you will tear away to make the opening. If you plan to install pull-down stairs, cut the opening to the appropriate size and follow instructions that came with the stair unit.
Frame a room area in the attic area. A slanted ceiling will require you to frame short side walls, but try to use all of the space available under the eaves. Install particle board flooring or plywood floors. Nail up drywall or plywood to create attic walls. Install places to hang clothes or lawn equipment by using metal hooks attached to overhead rafters. Build shelves in the storage space with leftover boards and plywood.
Place a large garbage can in the garage as you tear away attic ceiling material. Use a shop vaccum to manage the debris as well. A garage attic may have old insulation and other particles falling down, so anticipate this before you start the project.
Wear a paper face mask as you work. You don't want to inhale particles of debris or mold from an attic area.