Cull Lumber
Cull lumber consists of boards or logs rejected from a shipment or sort because they do not meet the minimum quality standards for any saleable grade. Culls may have severe defects such as rot, excessive warp, large holes, or other damage that make them commercially unusable for their intended purpose. Cull rates are tracked as a quality metric.
In-Depth Explanation
In the lumber industry, cull is both a noun (the rejected material itself) and a verb (the act of sorting out substandard pieces). Cull lumber sits below even pallet grade in quality, typically containing defects so severe that the wood has no commercial value for its intended use. Logs may be culled at the sawmill if they are too small, too crooked, or too rotten to yield usable lumber. Sawn boards may be culled during grading if they have split, rotted, or warped beyond recovery. The cull rate (percentage of total volume rejected) is an important metric for mill operations: high cull rates indicate problems with log quality, sawing accuracy, or drying practices and directly impact profitability. Some culled lumber finds secondary markets: slightly defective material might be sold for firewood, garden stakes, or composting bins. Cull logs may go to the chipper for pulp or biomass fuel. In timber sales, cull allowances are built into scaling rules to account for the portion of a log that will be defective, reducing the scaled volume and therefore the price the logger pays for the standing timber.
Usage Example
The grader pulled 15 boards from the stack as cull, noting that the combination of heart rot and severe twist made them unsuitable even for pallet stock.