The most common types are S.P.F., which is a spruce, pine, and fir mixture, and S.Y.P., southern yellow pine. If lumber will be exposed to moisture, you should use pressure treated lumber which is treated with a salt solution. Mahogany and cherry are the most common types of hard wood. Hard wood is used for furniture, floors, and paneling. A lumber dealer can help you find the right lumber for your job.
Lumber comes in standard sizes.
For example 2 x 4's are most common. The size measures the dimensions in inches of cut lumber. To make lumber strong, it is dried in a kiln before it can be sold. This drying causes shrinking so your lumber measurements are actually smaller. Lumber prices are a certain amount per thousand board feet.