A number of materials dominate when it comes to doing it yourself, materials that are used over and over again. Following is a look at these materials, as well as facts that will enable you to make better selections based on your needs.

Lumber

First of all, lumber is divided into softwoods and hardwoods. Both types follow different grading systems. Lumber is ordered and paid for according to nominal dimensions. Their actual dimensions are smaller due to the effects of milling and drying. Lumber prices are usually calculated by board foot, which is based on the size of the piece of lumber. Softwood lumber is manufactured and sold in standard sizes; hardwoods are milled in random lengths and widths to take advantage of every fractional inch of usable materials.

Softwood. Softwood accounts for the greatest share of lumber sold. It is used for virtually every type of construction, from rough framing to interior trim to projects. Southern pine is the dominant species in use today; others include “whitewoods” like fir, spruce, and hemlock. Specialty softwoods, such as cypress, redwood, and cedar, are frequently used for exterior construction because of their natural resistance to decay. Pressure-treated lumber, an ideal choice for maintenance-free outdoor projects, is softwood (usually pine) that has been chemically treated to resist weather, rot, and insect damage.

Hardwood. This is milled from slow-growing deciduous trees, such as birch, mahogany, and oak. Hardwood lumber is known as the premium lumber. More expensive than softwood, hardwood lumber is used primarily for cabinetry, furniture, millwork, trim, and fine flooring. Most lumberyards generally stock a limited assortment of hardwood species. So, for the best selection, buy from a yard specializing in this product.

Lumber Grades. Experts consider lumber grading both an art and a science. (And sometimes it seems more complicated than training in brain surgery.) Softwood lumber grades are based on visual and strength properties. Classifying softwood boards into two broad grading categories—select and common—makes it easier to choose the wood best suited for the project at hand.

Use select lumber (grades B and Better, C, and D) for trim, cabinetry, and anywhere else that appearance is a primary concern. Use common lumber (nos. 1, 2, 3, and 4) for general-purpose carpentry. And use 2 × 4-inch stud-grade lumber for framing applications.

Structural lumber is graded according to strength for specific engineering applications. Lumber grade is based primarily on the number of defects on the surface of each board. The “clearest” boards (those most free of knots and other mars) are FAS (Firsts and Seconds) Grade, followed by Select Grade, no. 1 Common, and no. 2 Common.

Lumber Surfaces. Lumber is also classified according to the surface treatment it receives before it leaves the mill. Rough lumber is not dressed (surfaced), although it is sawed, edged, and trimmed on all four surfaces. Dressed lumber is planed on the edges, on the sides, or both, to produce a uniform surface. The designation “S2S” refers to a board surfaced on both sides; S2S1E indicates a board surfaced on two sides and one edge.

Plywood

Plywood is another staple material. It comes in 4 × 8 foot sheets and consists of a sandwich of thin veneers or plies of wood bonded together for strength. It comes in ¼-, ½-, ¾-, and 1-inch thicknesses. Unlike lumber, the nominal size of plywood is its actual size. A 1-inch thick sheet is exactly 1 inch thick.

Plywood is also available for interior and exterior use. The latter uses exterior glue to bond the plies; the former uses interior glue.

Like lumber, plywood is graded:

Grade A does not have any defects on the face.

Grade B allows some defects and patches of defects.

Grade C allows small knots and knotholes.

Grade D allows large knotholes.

Grade and type are marked on the panel. Grade AC, for example, would mean that one side is defect-free and the other side has small knotholes.

When buying plywood, you should only buy the grade that you need. If the plywood is going to be painted, for example, you don't need to buy Grade A material—and then cover it with paint. Pick the grade that's suitable for the job.

Particleboard

Like plywood, particleboard comes in 4 × 8 sheets and in various thicknesses. It is made from wood scraps bonded together into sheets at high pressure. You might consider particleboard the “poor man's plywood” because it costs half as much. However, it is a good material, although it can't be used outdoors. It is twice as heavy as plywood and is murder on a blade saw. Moreover, it can't be stained or finished (just painted), and it doesn't accept nails on the edges. Still, it is a good building material for shelves and many other things, as long as you understand its limitations.

Drywall

Variously known as drywall, plasterboard, and gypsumboard, it's most commonly referred to by one brand name, Sheetrock. It comes in various sizes, but mostly 4 × 8 sheets and in 3/8-, ½- and 5/8-inch thicknesses.

Plasterboard consists of gypsum sandwiched between two layers of tough paper. Before it came along, there was only “wetwall,” or plaster. Drywall revolutionized building because everything became much faster to build. It comes in two grades of quality—visibly good and visibly bad.

Plaster is still the better wall. However, the craftsmen—bowlegged Old World men smoking malodorous cigars-are literally a dying breed.

When being installed on walls and ceilings, it is nailed to framing members. Then the seams or joints are covered with joint toe; and this, in turn, is covered with multiple coats of joint compound. Drywall is very cheap, and an excellent material. It is also great for patching holes.