CHAPTER 6
WOOD AND LIGHT FRAME STRUCTURES
When you prepare an engineering drawing,
regardless of type, you are required to apply
knowledge of the materials and methods of
construction. This chapter describes the uses,
kinds, sizes, grades, and other classifications of
wood as they apply to light frame building
construction; the various structural members and
their functions; and the different types of finishing
hardwares and fasteners used.
WOOD
Of the different construction materials, wood
is probably the most often used and perhaps the
most important. The variety of uses of wood is
practically unlimited. Few SEABEE construction
projects, whether involving permanent or tem-
porary structures, are built without using wood.
Temporary uses of wood include scaffolding,
shoring, bracing, and miscellaneous concrete
forms.
There are several types or species of wood.
Each type has its own characteristics and its
recommended uses. For most large projects, the
types and classifications of wood are given in the
project specifications. For smaller projects that
DO NOT have written specifications, the types
and classifications of wood are included in
the drawings. The types, sources, uses, and
characteristics of common woods are given in
table 6-1. In addition, the species, size classifica-
tion, and design values of common structural
woods are also listed in the Architectural Graphic
Standards.
LUMBER
In construction, the terms wood, lumber, and
timber have distinct, separate meanings. WOOD
is the hard, fibrous substance that forms the
major part of the trunk and branches of a tree.
LUMBER is wood that has been cut and surfaced
for construction use. TIMBER is lumber whose
smallest dimension is NOT less than 5 in. Another
term, MILLWORK, refers to manufactured
lumber products, such as doors, window frames,
window casings, shutters, interior trim, cabinets,
and moldings.
Sizes
Standard lumber sizes have been established
in the United States to permit uniformity in
planning structures and in ordering materials.
Lumber is identified by NOMINAL SIZES. The
nominal size of a piece of lumber is larger than
the actual DRESSED dimensions. Dressed lumber
has been SURFACED (planed smooth) on two
or more sides. It is designated according to the
number of sides or edges surfaced. If it has been
surfaced on two sides only, the designation is S2S
(surfaced 2 sides); if surfaced on all four sides,
S4S (surfaced 4 sides); or if surfaced on two sides
and two edges, S2S2E. Lumber is ordered and
designated on drawings by its nominal size rather
than by its dressed dimensions. Common widths
and thicknesses of lumber in nominal and dressed
dimensions are shown in table 6-2.
Classification
Lumber is classified according to its USE,
SIZE, and EXTENT OF MANUFACTURE.
When classified according to use, lumber falls into
three categories:
1. YARD LUMBER—grades, sizes, and
patterns generally intended for ordinary con-
struction and general building purposes
2. STRUCTURAL LUMBER—2 or more in.
in thickness and width for use where working
stresses are required
3. FACTORY AND SHOP LUMBER—
produced or selected mainly for manufacture of
furniture, doors, cabinets, and other millwork
6-1
