|
SECTION CONTENTS
Structural End- or Finger-jointed Lumber
End-jointed: CERT EXT JNTS
End-jointed: VERTICAL USE ONLY
Structural Face- or Edge-glued Lumber
WWPA Quality Control Procedures
Acceptance by Model Building Codes
Specifying Structural-glued Lumber
Click
here for details on new labels
for finger-jointed lumber joined with heat-resistant adhesives.
Download
a new Fast Facts on HRA finger-jointed lumber.
This information is available in the publication
Structural Glued Lumber (TG-9) which can be downloaded in Adobe Acrobat (PDF)
format.
Structural-glued Dimension Lumber
Structural-glued dimension lumber has gained wide acceptance in
the building and construction industry. It is accepted for use under
all model building codes and is interchangeable with solid-sawn
dimension lumber of the same size, grade and species, and is grademarked
accordingly.
The material makes efficient use of available wood
resources and can be manufactured in long lengths. Because it is
typically fabricated from dry material, it is exceptionally dimensionally
stable. This is a benefit in performance and makes it easy to hold
in inventory.
 Structural-glued products are commonly manufactured from lumber
that has been seasoned to below 19% moisture content and are grade
stamped "S-DRY" or "KD". Some finger-jointed
products are manufactured from unseasoned lumber and may be gradestamped
"S-GRN".
These products may be glued together in three ways:
end-jointed (where "fingers" are cut into the ends of
the pieces before they are joined, hence the nickname "finger-jointed"
lumber), edge glued or face glued. Structural-glued products are
available in a variety of species, grades and sizes for both general
and specifically-intended end uses.
Structural End- or Finger-jointed Lumber
WWPA is approved by the American Lumber Standard Committee, Inc.
(ALSC), under the U.S. Department of Commerce, to certify structural-glued
products in all species and species combinations. And while end-jointed
(finger-jointed) structural-glued Western lumber products may be
manufactured in any species, products are most commonly available
in:
Douglas Fir-Larch
Hem-Fir
Spruce-Pine-Fir (South)
Western Woods
Structural finger-jointed lumber is graded in accordance with the
National Grading Rule for Dimension Lumber (NGR), with additional
limitations applying to the characteristics allowed in the joint
area. These limitations are governed by Section 1.70 of the WWPA
Western Lumber Grading Rules, as approved by the Board of
Review of the ALSC. Dimension lumber grades, sizes, design values
(in base values), and routine adjustment factors apply.
Because structural finger-jointed lumber products
are graded using the same rules applied to solid-sawn dimension
lumber, the design values for structural-glued, finger-jointed
lumber are the same as those of conventional, solid-sawn lumber.
The grades of structural end- or finger-jointed lumber
produced by Western mills include:
STUD
SELECT STRUCTURAL
No. 1
No. 2
STANDARD & BETTER
STUD and No. 2 & BTR are the most widely available
of these grades.
Structural finger-jointed lumber is manufactured to
meet the requirements of two different types of end-use applications.
The first category is basically an all-purpose product, indicated
by CERT EXT JNTS on the grade stamp. The second category is appropriate
for use where the primary loading will be in compression parallel-to-grain,
indicated by VERTICAL USE ONLY on the grade stamp.
End-jointed Structural-glued
Lumber
"CERT EXT JNTS"
Finger-jointed products gradestamped CERT EXT JNTS are intended
for all structural applications. This lumber is assembled with a
waterproof, exterior-type adhesive meeting the requirements of ASTM
Product Standard D2559 and conforming to WWPA's Glued Products
Procedures & Quality Control, C/QC 101.97. Limitations on
knot size and placement near joints are highly restrictive. Testing
and quality control procedures are extremely rigorous. Refer to
the section below on "WWPA Quality Control Procedures."
The exterior-type adhesives for CERT EXT JNTS products
are suitable for bonding structural end-jointed and laminated wood
products for use in general construction where a high-strength,
waterproof adhesive bond is required.
These products may be 2x2 through 2x12 (with the
bulk of production being in 2x4, 2x6, 2x8, and 2x10), in any length.
Extra-long lengths are often available. Long lengths, up to 32'
or more, are one of the distinct advantages of structural-glued
finger-jointed products.
CERT EXT JNTS products may be used interchangeably
with any solid-sawn lumber product of the same species and grades.
The lumber may be used as beams, joists, rafters, studs, plates,
or in any other exterior or interior framing application.
End-jointed Structural-glued Lumber
"VERTICAL USE ONLY"
This type of finger-jointed product is appropriate for carrying
loads in compression as vertical framing members. These products
are grade stamped VERTICAL USE ONLY (previously stamped and known
as STUD USE ONLY).
VERTICAL USE ONLY finger-jointed lumber is manufactured
to meet the performance capabilities of solid sawn, end-loaded bearing
members where short-term bending or tension loads from lateral forces
such as wind, seismic and impact may be present, but where forces
from the conditions of long-term, sustained-bending or tension loading
are not present.
These products are typically assembled with a water-resistant
adhesive (indicated on the grade stamp as CERT GLUED JNTS) that
conforms to WWPA's Glued Products Procedures & Quality Control,
C/QC 101.97. VERTICAL USE ONLY products indicated as CERT GLUED
JNTS are limited to conditions where the glued joint will not be
exposed to repeated wetting and the moisture content of the wood
will not exceed 19% in use.
VERTICAL USE ONLY finger-jointed lumber production
is limited to 2x2 through 2x6, with lengths limited to 12 feet.
The term VERTICAL USE ONLY is recognized in daily selling conversation.
CERT GLUED JNTS is not typically referenced.
Handling advisory for CERT GLUED JNTS:
Although structural finger-jointed lumber grade stamped VERTICAL
USE ONLY-CERT GLUED JNTS is assembled with water-resistant adhesives,
these products should not be stored where water might collect in
a stack of lumber for an extended period. If lumber does get wet
during storage or delivery, it should be separated so it will dry
out, or be installed so it may dry in place.
Grade stamps for structural-glued, end- (finger-)
jointed products indicate the type of adhesive used. As noted earlier,
VERTICAL USE ONLY products are usually qualified as CERT GLUED JNTS
in the grademark. This occurs when a mill manufactures VERTICAL
USE ONLY lumber under WWPA's CERT EXT JNTS program using waterproof,
exterior- type adhesives.
Structural Face- or Edge-glued
Lumber
WWPA is authorized to certify the gluing process on a variety of
structural-laminated products (face-laminated, run-to-pattern laminated
decking and several other products) in sizes ranging from 2x6 through
5x8 in the species listed previously, plus Western
Red Cedar and Ponderosa Pine.
These products are most commonly used for structural
roof or floor decking in industrial, commercial or residential applications,
often with one side exposed for appearance.
When structural face- and/or edge-glued Western lumber
products have been assembled with a water-proof, exterior-type adhesive
meeting all of the requirements of ASTM Product Standard D2559
and subjected to WWPA's Glued Products Procedures & Quality
Control, C/QC 101.97, the WWPA stamp will indicate CERTIFIED
EDGE GLUING or CERTIFIED FACE GLUING.
For those products, WWPA's certification mark is
for the gluing process - the performance capability of the glue
line - and not necessarily for the grade of the product.
Face- and/or edge-glued products are
usually manufactured in proprietary grades. Thus, while WWPA may
provide quality control and inspection services for manufacturers
by certifying the bonding process, or the shear strength of the
glue line for these products, other design values such as bending
and tension for proprietary grades are the responsibility of the
manufacturer.
Sample WWPA grade stamps for structural-glued
lumber
WWPA Quality Control Procedures
WWPA gradestamped structural-glued lumber is subjected to rigorous
quality control and testing during production.
Test procedures are governed by WWPA's Glued Products
Procedures & Quality Control C/QC 101.97. These procedures
comply with criteria established by the ALSC's Glued
Lumber Policy. Under the WWPA procedures, samples are regularly
selected from normal production, including samples for certification
and hourly samples, for continuous quality control.
All structural-glued lumber products are subjected
to durability-cycle or cyclic-delamination test. These tests are
designed to simulate long-term, end-use conditions by subjecting
the glued joints to changes in moisture content that cause wood
to shrink or swell.
All structural-glued lumber products are also subjected
to strength tests. Depending upon the product, specimens are tested
under static-bending, tension or shear forces equal to or exceeding
the published design values for solid-sawn lumber. Corrective actions
are taken if any specimens fail strength or cyclic-delamination
tests.
Full-size samples of finger-jointed (end-jointed)
lumber stamped CERT EXT JNTS are tested in tension to verify joint
strength. Tension testing applies a uniform stress across the joint
so that joint strength will equal or exceed the published tensile-strength
design values for the grade being produced.
Finger-jointed lumber stamped VERTICAL USE ONLY is
subjected to bending tests. Because stud walls are often subjected
to bending from short-term lateral forces such as wind, earthquakes
and impact, tests are conducted to check the structural integrity
of the glued joints under such conditions.
Following the durability-cycle test, specimens are
subjected to fiber stress in bending forces to ensure joint strength
equals or exceeds the published bending-strength design values for
solid-sawn lumber of the same grade and species.
Both face- and edge-glued lumber are tested in shear
to verify joint strength. Because glue lines are subjected to shear
stresses in end-use applications, test specimens are selected and
subjected to a durability cycle, then further tested to ensure the
strength equals or exceeds the published horizontal-shear design
value for the product.
WWPA's ongoing quality control program ensures the
end user that WWPA gradestamped glued products can be used interchangeably
with solid-sawn lumber in full confidence.
WWPA: An Approved Quality Control Agency
Western Wood Products Association is approved by the American Lumber
Standard Committee, Inc. to supervise solid-sawn, glued and machine
stress-rated lumber production in accordance with the procedures
of the U.S. Department of Commerce Voluntary Product Standard
PS-20. WWPA also writes and publishes the Western Lumber
Grading Rules, which are approved by the Board of Review of
the ALSC according to the procedures of PS-20. WWPA's Glued Products
Procedures & Quality Control C/QC 101.97 comply with the
ALSC Glued Lumber Policy.
Only those products stamped with a WWPA grademark
have been subjected to WWPA's rigorous quality control and inspection
services.
Acceptance by Model Building Codes
Structural-glued lumber is referenced by all model building codes
and numerous standards-writing agencies:
-
2000 International Building Code (published by
International Code Council) Section 2303.1.1:
"Approved end-jointed lumber is permitted
to be used interchangeably with solid-sawn members of the same
species and grade."
-
2000 International Residential Code for One- and
Two-Family Dwellings (published by International Code Council)
contains three separate references.
Floor Framing, Section R502.1.3:
"Approved end-jointed lumber identified by a grade mark conforming
to Section R501.2 may be used interchangeably with solid-sawn
members of the same species and grade."
Wall Framing, Section R602.1.1:
"Approved end-jointed lumber identified by a grade mark conforming
to Section R602.1 may be used interchangeably with solid-sawn
members of the same species and grade."
Roof Framing, Section R802.1.2:
"Approved end-jointed lumber identified by a grade mark conforming
to Section R802.1 may be used interchangeably with solid-sawn
members of the same species and grade."
-
1997 Uniform Building Code (published by International
Conference of Building Officials) Section 2304.2:
"Approved end-jointed lumber may be used interchangeably
with solid-sawn members of the same species and grade."
"Structural end-jointed or edge-glued lumber
shall be permitted to be used interchangeably with solid-sawn
lumber members of the same species and grade when identified by
a label indicating compliance with end-jointed or edge-glued grading
rules."
-
1997 Standard Building Code (published by Southern
Building Code Congress International) Section 2301.6:
"End-jointed lumber may be used interchangeably
with solid-sawn lumber of the same grade and species."
-
1995 One- and Two-Family Dwelling Code (published
by Council of American Building Officials--ICBO, BOCAI and SBCCI)
Sections 502.1.3, 602.1, 802.1:
"Approved end-jointed lumber may be used
interchangeably with solid-sawn members of the same species and
grade."
"Design values for sawn lumber are applicable
to structural end-jointed and edge-glued lumber of the same species
and grade. Such use shall include, but not be limited to light
framing, studs, joists, planks and decking. When finger jointed
lumber is marked "STUD USE ONLY" or "VERT USE ONLY"
such lumber shall be limited to use where any bending or tension
stresses are of short duration."
Specifying Structural-glued
Lumber
Structural-glued finger-jointed (i.e. end-jointed) lumber is specified
in the same manner as solid-sawn dimension lumber.
For example, when ordering structural-glued lumber,
specify as structural-glued (or finger-jointed)
gradestamped lumber, and list the required grade,
species, size(s) and seasoning requirements. When applicable
or necessary, specify Fb and E Base Values as well.
Structural-glued lumber specification example:
Floor joists shall be No. 2 DF 2x10 WWPA gradestamped
Structural Finger-jointed Lumber, dried to the S-Dry standard
(with a minimum Base Fb= 900 psi and minimum E= 1,600,000).
A specification should include all species suited
to the job. This broadens availability and reduces costs. Consider
all grades suitable for the intended use, remembering that VERTICAL
USE ONLY products are limited in size to up to 6" in width
and 12' in length. To maximize economy, specify the lowest grade
suited to a job. Verify availability of species and grades with
local suppliers.
A specification for structural face-glued products
is similar; however, the grades are often proprietary and should
be verified with the product's manufacturer.
Refer to the WWPA Online
Member Buyers Guide for information on WWPA Member Mills that
produce glued lumber products in accordance with the Association's
Glued Products Procedures and Quality Control.
While every effort has been made to ensure
the accuracy of the Western lumber information included in this
Online Technical Guide, WWPA accepts no responsibility for errors
or omissions in the information presented herein, or for errors
which may occur in downloading and printing any of the files, nor
any liability resulting from the use of this information for design
and construction applications.
The WWPA Online Technical Guide is copyrighted
by Western Wood Products Association in Portland, Oregon. Ó
1997 WWPA
|