To do basic home-repair jobs, you need to know how to select building materials and how to use them. This article offers fundamental information on selecting lumber, plywood, drywall, and other materials for common do-it-yourself projects.

Lumber

Maybe you've noticed that lumber sizes are often misleading. The "nominal" cross-section dimensions of a piece of lumber, such as 2X4 or 1X6, are always somewhat larger than the actual, or dressed, dimensions. The reason is that dressed lumber has been surfaced or planed smooth on four sides (called S4S). The nominal measurement is made before the lumber is surfaced.

Board and Lumber Dimensions
One-by (1X) lumber is called "board":

 Nominal Size Dressed Dimensions (inches) 1X6 3/4X51/2 1X8 3/4X71/4 1X10 3/4X91/4

Two-by (2X) and four-by (4X) lumber is called "dimension lumber":

 Nominal Size Dressed Dimensions (inches) 2X2 11/2X11/2 2X4 11/2X31/2 2X6 11/2X51/2 2X8 11/2X71/4 2X10 11/2X91/4 2X12 11/2X111/4 4X4 31/2X31/2

Board measure is a method of measuring lumber in which the basic unit is 1 foot long by 1 foot wide by 1 inch thick, called a board foot. It is calculated by nominal, not actual, dimensions of lumber. The easiest formula for figuring nominal board feet is:

ThicknessXWidthXLength
12

The answer is in board feet. Lumber is often priced in board feet. However, most building material retailers and lumberyards also price lumber by the running foot for easier calculation. That is, a 2X4X8 is priced at eight times the running foot cost rather than as 5.333 board feet.

Plywood

Some projects require that you use or at least understand plywood. Knowing about plywood can save you money and may mean the difference between a successful project and one that fails.

For example, you don't need to buy an expensive piece of plywood that's perfect on both sides if only one side will be seen. Similarly, there's no sense in paying for 1/2-inch thickness when 3/8-inch plywood is really all you need. Plywood also comes with different glues, veneers, and degrees of finish. By knowing these characteristics you may be able to save money as well as do a better job.

Available at home centers, hardware stores, and lumberyards, plywood is better than lumber for some jobs. It is strong, lightweight, and rigid. Its high-impact resistance means plywood doesn't split, chip, crack all the way through, or crumble; the cross-laminate construction restricts expansion and contraction within the individual plies. Moreover, you never get "green" wood with plywood. When you buy a sheet of plywood, you know exactly what size you're getting, unlike with other types of lumber that have nominal and actual measurements. For example, a 4X8-foot sheet of 1/2-inch plywood measures exactly 4 by 8 feet and is exactly 1/2-inch thick.

Plywood is broadly categorized into two types: exterior and interior. Exterior plywood is made with nothing but waterproof glue and should always be used for any exposed application. Interior plywood, made with highly resistant glues, can actually withstand quite a bit of moisture. There is interior plywood made with IMG (intermediate glue), which is resistant to bacteria, mold, and moisture, but no interior plywood is made for use outdoors.

When purchasing plywood, look for a back stamp or edge marking bearing the initials APA or DFPA. APA stands for American Plywood Association, while DFPA is the Douglas Fir Plywood Association. These two organizations represent most of the plywood manufacturers, and they inspect and test all plywood to ensure quality is high and grading is accurate. The most critical plywood grading category for most home projects is the appearance grade of the panel faces (see the above sidebar on plywood grades).

Drywall

Drywall repairs typically mean patching rather than replacing. However, you should know something about drywall. Drywall, also known as gypsum wallboard, has all but replaced plaster in modern homes. Its rocklike gypsum core makes drywall as fire-resistant as plaster, and its heavy paper facing eliminates the cracking problems that plague plaster walls. Best of all, drywall is far easier to work with than plaster.

The standard-size sheets for walls measure 4X8 feet. All drywall sheets are 4 feet wide, but many building material outlets offer 10-foot and even 12-foot lengths. The most popular thicknesses of drywall are 1/2 inch (typically for walls) and 5/8-inch (ceilings).

Of course you can't really do much of anything with these materials without fasteners to hold everything together. We will cover the wide range of fasteners available to the handyman, starting in the next section with nails, screws, and bolts.