To ensure construction of a safe and durable
structure, wood products need to conform to appropriate product
standards as specified in building codes. Traditional solid-sawn
lumber became the first wood framing product to be governed
by a set of industry standards in 1924.
Since that time, industry standards have been established for
many other engineered wood framing products. Today, the building
consumer can choose from a wide range of excellent wood framing
products of consistent quality and uniformity.
Lumber and Timbers
Dimension lumber, 2" to 4" in thickness, includes solid-sawn
and end-jointed lumber. In a floor system, solid-sawn lumber
is most commonly used for floor joists, sill beams, and girders.
Timbers, 5x5 and larger, are frequently used for girders and
sill beams in a floor system.
Lumber and timbers must be properly grademarked. Grade marks
(Figure 2) identify the grade, species,
moisture content, producing mill, and inspection service. The
American Softwood Lumber Standard PS 20, of the U.S.
Department of Commerce, establishes lumber sizes, methodology
for assigning design values, nomenclature, inspection, and re-inspection
procedures, the National Grading Rules, an accreditation program,
and other functions.
Southern Pine Lumber
Southern Pine is the strongest structural lumber species for framing
applications. Due to its high strength and treatability, Southern
Pine is a preferred lumber species for building a raised floor.
Southern Pine lumber is readily available in a wide range of grades
and sizes.
Southern Pine lumber is graded according to the Standard
Grading Rules for Southern Pine Lumber published by the
Southern Pine Inspection Bureau (SPIB). Strength and stiffness
values for Southern Pine products in current SPIB rules have
been approved by the Board of Review of the American Lumber
Standard Committee. These design values enable determination
of allowable spans for lumber in specific end uses, including
floor joists. Refer to the SPC publication, Southern
Pine Use Guide, for complete grade descriptions, design
values and sample specifications.
Timber Piles
Foundation piles are typically peeled, round, pressure-treated
Southern Pine timber members, driven and embedded in the ground.
Timber piles may be required as a deep foundation for a raised
floor system in areas where soil conditions dictate. ASTM
D25 Standard Specification for Round Timber Piles establishes
physical properties and manufacturing requirements. Round timber
piles in service for foundation, land and freshwater use should
meet AWPA standards in Use Category 4C and/or Commodity
Standard C-3, Piles — Preservative Treatment by Pressure
Processes.
Glued Laminated Timber
Glued laminated timber, or glulam, is comprised of individual
pieces of lumber end-jointed together to produce long lengths,
and then bonded together with adhesives to create the required
beam dimensions. Glulam is generally used as a girder or beam
in a floor system. Glued laminated timber must meet the provisions
of ANSI/AITC A190.1 American National Standard for Structural
Glued-Laminated Timber, or the manufacturer's proprietary
code report.
Metal Plate Connected Wood Trusses
Wood trusses are assembled using dimension lumber and metal
connector plates. Trusses used as joists in floor systems are
usually the parallel-chord type. Assemblies using prefabricated
wood trusses shall meet the provisions of the governing building
code, and any additional requirements as set forth in ANSI/TPI
1 National Design Standard for Metal Plate Connected Wood Truss
Construction and the truss design drawings.
Prefabricated Wood I-joists
Wood I-joists are manufactured using sawn or structural composite
lumber flanges and structural panel webs, bonded together with
exterior-type adhesives, forming an "I" cross-section. I-joists
are commonly used for floor joists. Assemblies using wood I-joists
shall meet the provisions of ASTM D5055 Standard Specification
for Establishing and Monitoring Structural Capacities of Prefabricated
Wood I-Joists, the governing building code, and any additional
requirements as set forth in the manufacturer's proprietary
code report.
Structural Composite Lumber
Structural composite lumber (SCL) is manufactured with
parallel-laminated veneers or a network of wood strands laminated
together with a waterproof adhesive. Common forms of structural
composite lumber include parallel strand lumber (PSL), laminated
veneer lumber (LVL), and laminated strand lumber (LSL). Structural
composite lumber is generally used as a girder, beam or band joist
(rim board) in a floor system.
Structural composite lumber is required to meet the provisions
of ASTM D5456 Standard Specification for Evaluation of Structural
Composite Lumber Products, the building code, and any additional
requirements as listed in the manufacturer's proprietary code
report.
Structural Wood Panels
Wood panels can be manufactured in a variety of ways —
as plywood (cross-laminated wood veneer), as oriented strand
board or OSB (wood strands arranged in cross-oriented layers),
or composite panels (veneer faces bonded to wood strand cores).
Structural wood panels are commonly used as floor sheathing
in a raised floor system.
Plywood used in structural applications shall meet the provisions
of U.S. Department of Commerce Voluntary Product Standard
1 (PS1) Construction and Industrial Plywood, or U.S. Department
of Commerce Voluntary Product Standard 2 (PS2) Performance
Standard for Wood-Based Structural-Use Panels, or the manufacturer's
proprietary code report. Oriented strand board (OSB) used in
structural applications shall meet the provisions of Voluntary
Product Standard 2 (PS2) Performance Standard for Wood-Based
Structural-Use Panels or the manufacturer's proprietary
code report.
Rim Boards
Rim board can be manufactured using plywood, OSB, glulam, or SCL.
Rim board is designed to work in concert with a wood I-joist system,
filling the space between the sill plate and the bottom wall plate,
or between the top plate and bottom plate in multi-floor construction.
Wood structural panel rim board must meet the provisions of
the Performance Standard for APA EWS Rim Boards or the
manufacturer's proprietary code report. Glulam rim boards are
a resawn grade of glued-laminated timber manufactured in accordance
with the Performance Standard for APA EWS Rim Boards
and ANSI/AITC A190.1.
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