A successful do-it-yourself project starts with good wood. At first you may think there's a secret lumberyard code when you confront the many types and dimensions of wood. But once you take time to learn how the industry assigns grades and determines sizes, it's easy to choose and order the lumber best suited for your purpose--and maybe save money, too.
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Using a plan or sketch of your project, take a cutting list of all the pieces you need in each length to a lumberyard. You'll find a broader selection, better quality and more expertise there than at a home center.
Choose softwood or hardwood. Most construction lumber is softwood and is milled from fast-growing evergreens--pine, fir, cedar, redwood--in 2-foot increments from 6 to 20 feet in length. Hardwood comes from dense-grained deciduous trees such as maple, cherry and oak. Used for fine woodworking, it's available in more thicknesses and in random widths and lengths.
Match grade to purpose. To guarantee uniformity, lumber is graded by the quality of its surface. Terms differ for softwoods and hardwoods, but all describe appearance rather than strength. Look for clear- or select-grade boards for visible projects like shelves or decks. Select grade has few knotholes or discolorations. Common grade, which has more defects and is usually cheapest, is fine for items you plan to paint.
Decipher lumber sizes. Sawmills cut wood into standard sizes, from 1 to 8 or more inches thick and 4 to 12 or more inches wide. When this rough lumber is planed, it loses 1/8 inch or more from each dimension, so a 2-by-4 is actually 1.5 by 3.5 inches.
Buy precut wood for popular uses--stair treads, window trim, shelving and pieces such as spindles and furniture legs. These save time and take the guesswork out of choosing species and grade, but cost more.
Order lumber by the linear foot or the board foot. Use the former to order moldings, trim and same-dimension lumber (30 linear feet of 1-by-6 boards, for example). Use the latter to order random- width hardwood by volume for building furniture. As an example, 1 board foot equals 144 cubic inches.
Select pine or fir for rough-cut projects and framing. Pick hardwood for fine furniture and projects that will get a clear finish. Pine cuts easily and takes paint and varnish well. In hardwoods, ash and poplar are typically painted because they stain unevenly. Stain maple and oak to highlight their grain. Walnut is strong and stains nicely; beech looks great varnished or stained but is hard on saws.
Inspect for defects. Knots are a cosmetic flaw (unless they're large or about to pop out), but splits often get wider. To check for warping, lift one end of a board and sight down its edge to see if it bends in either direction. To check for bowing or arching, lay the wood on a level surface. A seriously bowed, cupped or crooked board is seldom workable, although minor bows will flatten out as you nail.
Check moisture content, or seasoning. Lumber is kiln-dried (KD) or air-dried (AD). KD wood has about 8 percent moisture content; AD, 15 to 25 percent. For indoor furniture, KD lumber is preferable because the wood shouldn't dry out any further.
Choose plywood for its strength and stability, the result of gluing several thin layers of wood together at right angles. Plywood used for sheathing, subfloors and rough carpentry typically has a veneer of Douglas fir, graded on each side. If both sides will show in your finished project, buy A-A or A-B grade. Plywood comes in 4-by-8-foot panels 1/4, 3/8, 1/2, 5/8 or 3/4 inch thick ($14 to $40 for Douglas fir, according to grade and thickness).
Use hardwood-veneer plywood for furniture and cabinetry. It also comes in 4-by-8-foot sheets, but most dealers will sell a partial sheet. Thicknesses range from 1/8 to 3/4 inch; the latter costs $65 to $105 per sheet. Be sure to ask for cabinet-grade plywood, which is typically 9-ply birch coming from Denmark and other sources, and available through plywood distributors. Use finish-grade plywood for built-in projects, combined with more costly solid woods for exposed areas. You can get plywood with a veneer of virtually any kind of wood in the world.
Shop for alternatives to old-formula pressure-treated lumber (see Warning) for building decks, picnic tables and play structures. Heartwood grades of redwood and cedar are naturally rot- and insect-resistant; prices vary widely by season and location. Consider composite (wood-plastic) lumber for durable, splinter-free decking. Engineered lumber products come from small-diameter and fast growing plantation trees. They use wood fiber more efficiently than conventional lumber, reducing pressure on old-growth forests and resulting in stronger structures. Choose exterior plywood--made with waterproof glue--for other outdoor projects.
Tips and warnings
- The only way to ensure that you get high-quality wood is to pick out the boards yourself-- or at least approve their selection.
- Lumber describes milled wood more than 2 inches thick. Thinner wood is technically a board. Wood thicker than 5 by 5 inches is timber. Now you know.
- Lumber prices vary by season, region, availability and demand.
- Once you've calculated how much wood your project requires, get 10 percent extra to allow for mistakes and to match grain. Don't buy more than that. Wood can warp if it's not stored in ideal conditions.
- Countries outside the United States have different systems for sizing lumber.
- Lumber preserved with chromated copper arsenate (CCA) is potentially hazardous. It will not be sold after December 31, 2003. Ask about alternatives.