All the miracles of modern synthetics haven't ousted wood from its spot as our number-one building material. It is easy to work, plentiful, durable and versatile. You can pick it for toughness, flexibility, beauty, hardness or softness. In the form of plywood, it comes in almost any size you need.

But the handyman who goes to the lumberyard with a gleam in his eye may come out with a glazed look and a thin wallet. Confusion about grades, dimensions, and prices may needlessly skyrocket a materials bill.

Actually, there is no mystery about lumber grades, sizes and charges. But the man at the stacks hasn't time to explain them. In the following pages you will find basic facts and money-saving tips about structural lumber, boards, plywood, millwork and craft woods. These will help you decide what you need, and when to accept or reject substitute material. If you want the dealer's assistance, try to go to the yard on a weekday. Saturday is his busy day and he may not have the time to be helpful.

WOOD FOR THE HOME CARPENTER

There are three ways to buy wood for the project you're planning. All cost money, but a couple can be downright extravagant. One is to tell the yard man you want "some 3/4" stuff about so big and that long" and hope for the best.

Another is to tell him what's building and let him try to outguess you as to construction, finish, and how much money the job is worth to you. He may play safe and sell you top-grade stuff, charging you accordingly.

The third is to know how lumber is sold and figure out what you want before stepping out of the house. This can save you time at the yard, keep the dealer your friend and earn you cash saving. To buy like this, you need only know some basic facts about the trade.

Hardwood or Softwood?

Whether the wood is easy or hard to dent or drive a nail into is not what decides its type. Some hardwoods are fairly soft, and vice versa. Hardness will vary, too, with the part of the tree the piece comes from, and its moisture content. There is no sharp dividing line.

Woods are properly classified as hard or soft solely by the two groups of trees they come from. Those from broad-leaved deciduous trees (which shed their leaves each year) are hardwoods. Those from coniferous trees or evergreens, which have needles or scalelike leaves, are softwoods. Most of the wood in the ordinary lumberyard belongs to this class.

How Dry Is It?

If you're putting cupboards in a heated house, the wood had better be well seasoned or you'll wind up with cracks where the joints used to be. For exterior work it can be less dry, and for framing a house even poorly seasoned lumber will do in a pinch. Such wood is easy to nail, can be straightened if crooked, and will be fairly dried out, if the weather stays good, by the time you get around to enclosing it.

Green wood may be so wet it spouts water when a nail is driven in. You can sometimes buy unseasoned wood so much cheaper that it may pay to "stack and stick it" yourself for air drying. Or you may be able to put it up green in such a way that the opening of joints won't show. One way is to nail battens along the joints to one board only, and nail them to the other only after shrinkage has occurred. The wood is, of course, left unpainted. Remember that wood shrinks least lengthwise, and most across the grain. In a long board, however, even lengthwise shrinkage can open a corner joint half an inch.

If you want to test wood for moisture content and shrinkage, saw off a piece 1" long and exactly 6" across the grain. Weigh it carefully. Bake in the oven at 212° for at least four hours. Then measure it or compare it to an undried piece of the same stock. If you want moisture content, find the difference between wet and dry weight, and divide the difference by the dry weight. Example: a piece weighing 12 oz. originally and 8 oz. after drying (difference 4 oz.); dividing 4 by 8 gives 1/2, or 50% moisture content.

For interior applications such as trim and cabinets, lumber should be kiln-dried. Such stock may have from 6% to 12% moisture content.

HOW A TWO-BY-FOUR DWINDLES

Framing lumber may be either kiln-or air-dried and have up to 20% moisture. Anything with more than that is usually considered green lumber. Beware of painting such wet wood; chances are the paint will not hold, but only retard seasoning.

Rough, Surfaced and Worked

Lumber comes from the saw cut to nominal sizes such as 2x4, 2x6, 4x4, and so forth. In this form it is classified as "rough." Run through a planer, it is known as "surfaced," and decreases in size by the amount of wood removed. A nominal 2x4 surfaced on four sides (S4S) thus shrinks to 13/8"x29/8" in cross section, a 1x6 board to 69/32"x45/8". A "five quarter" board, nominally 5/4" thick, comes to 17/16" when dressed.

Some lumber can be bought surfaced two sides (S2S) or one side and one edge, and so forth. Rough lumber, if available, is a good choice for some jobs, although hard on the hands. Rough rafters may be good, for example, while rough studs may cause trouble, since difference in width would make the walls irregular. Dressed or surfaced lumber, on the other hand, is uniform. Planning straightens the pieces and makes the sides and edges parallel. Uniform width or thickness is important when pieces are to form an even surface for further construction. Studs in a wall, for instance, are placed on edge and therefore should be sized across the width on one or both edges. The same is true of floor joists. It's wasteful of time to lay odd widths and then dress them to match.

A third classification, "worked" lumber, refers to stock that has been run through a molder or similar machine and made into siding, casing, bead or molding.

Surfaced, or sized, lumber is grouped in three categories: Yard lumber includes boards and dimension lumber up to 5" thick. Structural timber are 5" or more. Both groups are graded as to quality with the use of the entire piece in mind, therefore a bad defect downgrades the piece. Factory and shop lumber, on the other hand, is meant to be cut up and permits defects between usable sections. This grouping has special interest for the craftsman.

How Wood Is Graded

All but the most expensive lumber has defects. Grading regulates the size and number of these. You should know enough about grading to buy the cheapest lumber suitable for your purposes and also to recognize inferior grades if they are sent to you by mistake. The safety and durability of a garage or house addition may depend upon your caution. Where building inspectors check on construction, you may have to rebuild anything in which less than required grades have been used.

In grading framing lumber, strength is the chief criterion. For this reason not only the size of the defects and whether they're sound or loose, but also their location is taken into account. A knot near the end of a 2x4 impairs its strength less seriously than one in the middle or near the edge. Therefore larger end knots are allowed. Checks (end cracks) may be only one-fourth the thickness of a piece of No. 1 common; or, if two checks are opposite each other, their total must be no more than one-fourth of the thickness. In No. 2 common this tolerance goes up to one-third. An accompanying diagram shows these grading principles.

Money-Saving Tips

Besides using the lowest serviceable grade for the job in hand, you can sometimes trade time for a cash saving by picking over cull lumber. Plenty of split and otherwise damaged stock is usable. But it may require extra sawing to square off the ends, and only you can decide whether it pays.

Milling defects sometimes put lumber on the bargain counter. Hit- and-miss surfacing, in which the knives missed low sections, still leaves boards suitable for sheathing and subfloors, for instance. Some price arithmetic will show whether such lumber is worth buying.

Large beams, like those over wide garage doors, can be bought as timbers, but inside defects may be hidden and the pieces are hard to handle. A good alternative is to spike two pieces of 2" stock together side to side. Another lumber-saving device, building regulations permitting, is to use 2x4 ceiling joists over halls and for spans of 10' or less.

Weaknesses in rafters and joists that show up after they are in can be corrected by nailing "scabs" of 1" stock on each side of the piece. They should extend about 2' each way beyond the defect. Studs bowed edgewise can be straightened by making a saw cut in the concave edge and expanding it with a wedge, afterward reinforcing the spot with scabs.

It's a good idea to clamp the member against a stiff, straight piece before you nail on the scabs.

Clear stock for porch columns comes high. A stained or natural finish can be satisfactory even if there are a considerable number of firm knots. For a painted finish you can use even rough or knotty pieces. Chisel back the knots, plug the holes with wood held in with waterproof glue, and fill rough spots with a good surfacing putty or fine sawdust mixed with waterproof glue. Sand well all over when the glue has set.

It's good practice to set door and window jambs before plastering, letting them take the place of plaster grounds. If you want the best finish in the least time, use kiln-dried grade B and better, vertical grain. This grade allows only two or three pitch pockets in a 12' length of 8" board, no knots or skips on the face, and no cupping.

If you can pick your own jamb stock and are sure of getting straight pieces, buy as near finished width as possible. For delivery, sight unseen, better get it wider so that edges can be jointed straight without making the material too narrow. This also applies to "pulley stile," jambs for double-hung windows already grooved for the parting bead. If this material is bowed edgewise, jointing the edges will still leave the groove curved.

Unless you are certain of getting worked stock that is straight, you'd better buy plain boards and groove it yourself after jointing to width.

Grain appearance is a clue to how well the wood will hold paint. Flat-sawn lumber with wide slashes of hard grain may flake paint off the hard parts. If hard grain appears as threads, it should hold paint well, but the broad hard grain of summer wood makes a board a poor prospect for painting.

When You Want Boards

By boards the lumberman means stock less than 2" thick and usually over 6" wide (narrower boards may be classified as strips). Pricewise, such stock adds up fast. Therefore it's important to buy sizes that will cut with a minimum of waste, and to get the cheapest grade adequate to the job.

What Wood Will You Use?

Coast to coast, our forests offer a variety of useful building lumber. Your dealer will ordinarily stock the kind that grows nearest and therefore costs least to haul to his stacks. It will usually cost you less, too.

Douglas Fir (also known as Oregon Pine) is neither fir nor pine but a species in its own right. It is very strong for its weight, resists soil moisture and decay, takes a good finish, and is made into plywood, doors and trim as well as framing stock.

White Pine (also known as Northern, Eastern and Canadian White Pine) grows from the East Coast to Minnesota and as far south as Georgia. It is much used for millwork as well as framing, is easy to work and less resinous than other pines.

Idaho White Pine (Western White Pine) has characteristically colored small tight knots. Better grades are used for the same purposes as Northern White Pine, while the lower grades are used for construction lumber and knotty-pine paneling.

Ponderosa Pine (California White Pine or Western Yellow Pine) has a number of regional names but is not truly a white pine. It is much used for millwork. If it will be exposed to weather, it should be treated to resist moisture.

Southern Pine (Southern Yellow Pine) takes in loblolly, pond, slash and other pines growing from Virginia to Texas. Some are known commercially as North Carolina Pine. Uses run from structural timber to molding.

Eastern Hemlock is found as far west as Wisconsin. West Coast Hemlock is often intermixed with Douglas Fir, and can be had in wide sizes of vertical-grain boards.

Redwood is also a West Coast wood, valuable for purposes ranging from ceiling to sheathing. Free from resin, it takes paint well and is resistant to weather and decay.

Cedar and Cypress are useful for sheathing, exterior trim, and siding.