Lumber, Plywood, and Other Wood Products - Carpenter's and Builder's Math, Plans, and Specifications - page 70

properties to an increasing number of former yard items has diluted
the meaning of the term yard lumber.
In nonstress-graded structural lumber, the section properties
(shape, size) of the pieces combine with the visual grade require-
ments to provide the degree of structural integrity intended. Typi-
cal nonstress-graded items include boards, lath, battens, crossarms,
planks, and foundation stock.
Boards (sometimes referred to as commons ) are one of the more
important nonstress-graded products. Common grades of boards
are suitable for construction and general utility purposes. They are
separated into three to five different grades depending upon the
species and lumber manufacturing association involved. Grades may
be described by number (No. 1, No. 2) or by descriptive terms (Con-
struction, Standard).
Since there are differences in the inherent properties of the var-
ious species and in corresponding names, the grades for different
species are not always interchangeable in use. First-grade boards
are usually graded primarily for serviceability, but appearance is
also considered. This grade is used for such purposes as siding,
cornice, shelving, and paneling. Features such as knots and knot-
holes are permitted to be larger and more frequent as the grade
level becomes lower. Second- and third-grade boards are often used
together for such purposes as subfloors, roof and wall sheath-
ing, and rough concrete work. Fourth-grade boards are not se-
lected for appearance but for adequate strength. They are used
for roof and wall sheathing, subfloor, and rough concrete form-
work.
Grading provisions for other nonstress-graded products vary by
species, product, and grading association. Lath, for example, is
available generally in two grades, No. 1 and No. 2. One grade of
batten is listed in one grade rule and six in another.
Appearance Lumber
Appearance lumber often is nonstress-graded. However, it forms
a separate category because of the distinct importance of appear-
ance in the grading process. This category of construction lumber
includes most lumber worked to a pattern. Secondary manufacture
on these items is usually restricted to onsite fitting, such as cutting to
length and mitering. There is an increasing trend toward prefinish-
ing many items. The appearance category of lumber includes trim,
siding, flooring, ceiling, paneling, casing, base, stepping, and finish
boards. Finish boards are commonly used for shelving and built-in
cabinetwork.