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Lumber yards stock wood in two forms, rough and surfaced. Rough lumber is in the form in which it comes from the sawmill. The edges may not be square, and the surface is rough and shows saw marks. Surfaced lumber is planed on two or more sides and has square edges. Lumber is measured in the rough state, and surfaced lumber, therefore, will measure slightly less, due to the planing. In most cases, the surfaced lumber will be about one quarter of an inch under the rough. Thus, a piece of 2 x 4 inch stock will be about 1 5/8 by 3 5/8 inches when surfaced on all sides. The home mechanic will find surfaced lumber best for practically every purpose. It is much easier to work with, particularly when all sides are square. The planing required to make surfaced lumber out of rough takes only a short time with the machine used in a lumber yard, but it would entail hours of hard work with a hand plane, with results always imperfect. The difference in cost between rough and surfaced lumber is not enough to warrant the extra work. Secondhand Lumber. Secondhand lumber can be purchased at many yards and has many uses, but it should be remembered that used lumber is not as strong as new wood and consequently, should be limited to those jobs in which there is no great strain. Be very careful when working with used lumber not to strike a nail with the saw or plane. Examine the lumber carefully before working with it, watching for nails that have lost their heads and are difficult to find. Measuring Lumber. Lumber comes in many different standard lengths, running to about eighteen feet. The widths vary from two inches to twelve, and the thickness from one inch to eight. Most lumber yards always have a few odd-size pieces of board, and these can be used for small household jobs where it would be impractical to get a full-length board and saw it up into various dimensions and shapes. The board-foot is the standard measurement for lumber. This unit of measurement is equal to a board one inch thick by twelve inches wide by twelve inches long. To find the number of board feet in a piece of lumber, multiply the length in feet by the width and thickness in inches and divide by twelve. Green Lumber. When lumber is first cut it contains a considerable amount of moisture. Under normal circumstances, lumber is stacked in piles after it has been sawed, and left to dry. During this period most of the moisture will evaporate, but a small portion will remain, and this may require several months or more to disappear. Still-moist lumber is called. "green." After most of the moisture has evaporated, the lumber is called "seasoned." Green lumber is not suited to most building needs because it shrinks as it dries, and to build a house of green lumber is to court much future trouble. To hasten the drying of the wood , green lumber is often put in an oven called a kiln. This is an artificial method of seasoning the wood and, consequently, makes the wood more expensive. To test a piece of wood to see if it is still green, weigh it, and then place it in an oven and dry it completely. Remove it from the oven and weigh again. If the weight is considerably less, the wood was green. If one piece of lumber in a load is green, it can be assumed that the rest is also. Hardwood cannot be artificially seasoned, and only well-seasoned wood should be used for furniture and other precise work. Boards. One of the most familiar boards is the common board with four flat sides. This can be used for a variety of jobs. Shiplap boards have their edges cut out so that they will fit together. Tongued and grooved boards have a tongue on one side and a groove on the other so they can be fitted together tightly.
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