Timber sawed into planks, boards, beams, etc. of commonly used sizes.
Lumber appearance
Divided into industrial, architectural and premium grades, the quality of this lumber is based on its finished appearance.
Lumber fencing
Fencing, in various patterns, created from 2 x 4's or 4 x 4's.
Lumber grade
As outlined by the American Softwood Lumber Standard PS 20-70, having guidelines by the National Grading Rule Committee, hardwood lumber is graded as to quality from "Firsts" which has 91 1Ú2 % clear on both sides to No. #B common, 25 % clear on one side. Grades for Softwood Lumber run from Select A, which is the best and can be used with a natural finish, to Common No. %, which is only good for filler.
Lumber grade stamp
National Grading Rule Committee marking that identifies lumber by grade and provides additional information.
Lumbermill
Place where logs are sawed into lumber.
Lumberyard
Place where lumber is stored and sold.
Lumen
An empirical measure of the quantity of light. It is based upon the spectral sensitivity of the photosensors in the human eye under high (daytime) light levels. Photometrically it is the luminous flux emitted with a solid angle (1 steradian) by a point source having a uniform luminous intensity of 1 candela.
Lumen maintenance
A measure of how a lamp maintains its light output over time. It may be expressed as a graph of light output vs. Time or numerically.
Lumens per watt (lpw)
A measure of the efficiency, or more properly, "efficacy" of a light source. Efficacy is easily calculated by taking the lumen output of a lamp and dividing by the lamp watts. For example, a 100-watt lamp producing 1750 lumens has an efficacy of 17.5 Lumens per watt.
