How To Pick Lumber

There are several points to keep in mind when picking lumber. Many times the same stack of lumber will contain striking differences between individual pieces - differences that can affect the outcome of the job. Before you buy lumber, sort through the stack yourself to check for defects.


Moisture Content: High moisture content means the wood is "green" - or unseasoned. Before it's ready for use, most lumber is air or kiln dried. If you buy greenwood, be prepared for possible problems from splitting, warping, nail-popping and shrinking wood.

The highest grades of lumber will normally be stamped 11MC-1511, indicating the moisture content can not exceed 15 percent. Select and Finish grades are required to meet this standard.

Heartwood or Sapwood: Sapwood, next to the bark, contains the growth cells. Heartwood is the inactive wood nearest the center of a living tree.

For most house framing lumber, Heartwood and Sapwood differences can be ignored. However, for finishing work, you may prefer one instead of the other because they differ in color.

Heartwood is also denser and resists decay more efficiently. That's why many building codes require lumber within 6 inches of the ground be heartwood - such as redwood, cedar or cypress.

Common Lumber Defects. Always examine each piece of lumber thoroughly. Sight down the face and edges and look for any number of common defects. For example, a crook (edge-line warp), bow (face warp) , cups (bends across the face) , twists (multiple bends), knots (loose knots may fall out), shakes (hollows between growth rings), checks (cracks along growth rings), cracks (checks that go all the way through the wood), and wanes (edges of wood that aren't trimmed).

Also check for rotting, staining, insect holes and pitch pockets (sap reservoirs below the surface).

Lastly, whenever possible, choose vertical grain lumber (wood that has parallel grain lines running the length of the wood), rather than flat grain (marbled appearance); it's less likely to warp or shrink noticeably.