Putting together a materials list is the first step in framing a garage. Because you'll know exactly what you need to complete the job, you'll save yourself time and money and avoid the headache of over- or under-ordering. Your building plans will show every piece of lumber in the garage, but you can also determine your material needs by using a few simple calculations.
Review your building plans. They will list the dimensions of every wall in the garage.
Figure 14, 2-by-4s for every 10 feet of wall length. This includes lumber for the sill plate (bottom, horizontal wall component), wall studs (vertical wall component) and doubled top plates (top, horizontal wall component). The sill plate should be pressure-treated lumber since it will lie on the concrete slab.
Count several 2-by-12s to use as headers, horizontal components that span door and window openings. Each header is five inches wider than the opening it spans, so the exact number of 2-by-12s needed will depend on the number of door and window opening shown on your plans. Add three or four more 2-by-12s for jambs (vertical part of door frame).
Divide the length of the garage by two to determine the number of roof trusses required.
Multiply the length by the width of each wall and of each side of the roof to determine the area of each. Add the totals to get the total surface area of the garage. Divide total surface area by 40 square feet (area of 5-by-8 sheathing) to determine the sheathing needed for cladding and roof decking.
Add one box of 16d framing nails to complete your framing materials list.