Commercially important Western lumber softwood species are
grouped into Standard Combinations according to structural performance
characteristics, and by structural or appearance characteristics
into the Alternate Combinations.
The designated species combinations are a result of
marketplace preferences. Species are grouped for ease of design.
The Standard Species Combinations are for use primarily in the design
of structural applications. These combinations allow architects
and engineers to work with six basic sets of numbers, rather than
25 Western species individually. Species within each combination
share similar structural performance properties and may be used
Species grouped in the Alternate Combinations are
similar visually and interchangeable in appearance applications.
Some Alternate Combinations, such as ES-LP (Engelmann Spruce-Lodgepole
Pine), are uniquely suited for structural applications as well.
Design values assigned in these combinations result
from the In-Grade lumber testing program in which over 70,000 pieces
of lumber were evaluated to the breaking point in order to assign
digne values of mechanical properties. This industry-sponsored research
initiative, the most extensive ever conducted for a building product,
concluded in 1991 and resulted in reliable design values assigned
to all North American lumber.
Species Characteristics and End
Douglas Fir-Larch (DF-L)
This species combination has the highest modulus of
elasticity (MOE or E) value (the stiffness factor) of all North
American softwoods. In strength properties, DF-L has the highest
ratings of any Western softwood for fiber stress in bending, tension
parallel to grain, horizontal shear, compression perpendicular and
compression parallel to grain.
Douglas Fir (DF) is often the standard
against which all other framing species are measured. Its strength
combined with a superior strength-to-weight ratio, high specific
gravity (for excellent nail and metal truss plate-holding capability),
excellent dimensional stability (giving "green" DF products the
ability to season well in service), the moderate decay resistance
of its heartwood, and documented excellent performance record against
strong forces resulting from winds, storms and earthquakes, have
given Douglas Fir its reputation. It is also tight knotted and close
grained, adding the bonus of beauty to its structural capabilities.
Color, grain pattern, knot size and type are addressed in the rules
for appearance grades.
Douglas Fir is the major species produced in the West,
with more volume shipped than any other species, and its sterling
performance history is recognized the world over. It is abundant
and widely available in second and third-growth stands yielding
products in multiple grade classifications: dimension and other
framing products, engineered structural products such as MSR, finger-jointed,
and glu-laminated products, high (clear) to low (economy) grade
appearance products, and industrial and specialty grades. DF doors,
manufactured from products in the Factory & Shop grade classification,
are renowned for their beauty and performance.
Douglas Fir's light rosy color is set off by its remarkably
straight and handsome grain pattern. Sapwood is white to pale yellow;
heartwood is russet with high contrast between the springwood and
summerwood. While similar, Western Larch is slightly
darker in color, with the heartwood being a reddish brown and the
sapwood a straw brown.
Douglas Fir grows throughout Western forests with
the most abundant region being in the coastal climates of Oregon,
Washington and northern California. In the Inland Region, east of
the crest of the Cascade Mountains, Douglas Fir and Western Larch
often grow in intermixed stands. Coastal and Inland Douglas Fir
and Western Larch share similar structural performance characteristics
and are often combined in dimension lumber structural products.
While DF products from the various parts of the vast
Western Region are virtually indistinguishable in terms of appearance,
the growing conditions of different parts of the region contribute
to the physical working properties of the species. Consequently,
Douglas Fir's growing region is identified in the grade stamp. Douglas
Fir from the US coastal and inland regions is designated as DF,
or when combined with Western Larch as DF-L. (Canadian DF products
are identified as DF-North and have different design values.) Douglas
Fir originating from Arizona, Colorado, Nevada, New Mexico and Utah
is designated as Douglas Fir-South, or DF-S. Coastal DF represents
73%, inland DF-L represents 26%, and DF-S represents 1% of the species'
production in the Western U.S.
Hem-Fir is a species combination of Western
Hemlock and the true firs (Noble, California Red,
Grand, Pacific Silver and White fir). With strength properties
slightly below DF-L (and above DF-S), this is an extremely versatile
species group and useful for multiple, general-purpose framing applications.
In the structural framing grades, Hem-Fir is capable of meeting
the span requirements of many installations.
Hem-Fir is often considered by those seeking wood
with a very light color as the most desirable of the Western softwoods.
It is as light or lighter in color than some of the Western pines
but stronger. Products are available in structural, appearance and
remanufacturing grades. It is easily pressure treated with preservatives,
making it useful for decks and other outdoor amenities.
Hem-Fir products are white to a light straw color,
sometimes with a slight lavender cast, especially around the knots
and in the transition area between the spring and summerwood's growth
rings. The heartwood is not distinct. Sometimes small, delicate
dark grey or black streaks appear in the wood. Hem-Fir is fine grained
and even textured, with a refined appearance. In the clear and nearly
clear appearance grades, these products lend formality to wood interiors.
Hem-Fir is often specified for high quality case goods, doors, moulding
Douglas Fir-South (DF-S)
Products originating from trees grown in Arizona,
Colorado, Nevada, New Mexico and Utah are designated Douglas Fir-South.
Douglas Fir-South is set apart from DF or DF-L by its slightly lower
design values for structural applications. DF-S is always marketed
separately for design and engineering, but interchangeable with
DF and DF-L in appearance grades.
This species combination, classed as moderately strong,
is cross-continental in origin. Because of similar design values,
the combination includes Engelmann and Sitka spruces,
and Lodgepole Pine from the West, along with Balsam
Fir, Jack Pine, Red Pine and several eastern spruces from
the U.S. Northeast. SPF-S grademarked products may originate from
either region and be graded either by or according to grading rules
published by WWPA, the West Coast Lumber Inspection Bureau (WCLIB),
or the Northeastern Lumber Manufacturers' Association (NELMA).
SPF-S design values make it appropriate for general
framing applications. In the higher, structural light framing grades,
dimension products are appropriate for light trusses and other engineered
applications. In MSR lumber, SPF-S lumber is interchangeable with
Canadian SPF lumber because Western mills conduct manditory quality
control on the specific gravity of SPF-S,
The alternate (Western only) species combination of
Engelmann Spruce and Lodgepole Pine (ES-LP) is well
suited for truss design and other engineered applications. Additional
information on ES-LP for truss design is detailed in WWPA's Tech
Note No. 3 available from the Association's Technical Services
Engelmann and Sitka spruces
are nearly white in color with a distinctive, slightly pinkish-grey
tone. Relatively small, uniformly distributed knots add to the appeal
of the medium to fine texture and straight grain.
Lodgepole Pine has relatively straight
grain, white to yellow sapwood with light, reddish-brown heartwood.
Knots do not bleed through paint. It is used for interior paneling,
joinery, structural timber and poles. When creating interiors or
rustic designs with Western pines, remember that while Lodgepole
resembles other Western pines in appearance, it is the strongest
of the Western pines. This makes LP additionally useful for selected
structural elements when a "pine aesthetic" is desirable.
In a structural performance context, the term, "Western
Woods" specifically indicates a combination of the Western pines
(Ponderosa, Sugar, and Idaho White Pine), Mountain
Hemlock and Alpine Fir because these species
share similar design values. While these species are not the strongest
among Western species, they can carry heavy loads when large members
are used. Their real appeal and strengths are in the appearance
grades: COMMONS, ALTERNATE BOARDS, SELECTS and FINISH, and in the
Factory and Shop products.
The term "Western Woods", when not used in connection
to assigned design values and structural performance, may also describe
any non-specific combination of any or all Western species except
Ponderosa Pine is perhaps the most beloved
of the Western pines. Its soft texture and light color distinguish
it from the Southern pines; its wood is among the most beautiful
of all pines. Sapwood is nearly white to pale yellow, heartwood
is light to reddish brown. Clear finishes with UV blockers can help
retain its freshly-milled color. It has a pleasant pine scent and
is slightly resinous.
Moderately strong, straight grained, and dimensionally
stable, it is favored for all kinds of joinery including window
frames, doors and architraves, and is used for shelving, paneling,
trim, and furniture. It is the species of choice for premium-grade
Sugar Pine is the tallest of the Western
pines, bearing enormous cones that can be well over a foot long.
It is moderately strong with a fairly uniform texture. Sapwood is
creamy white, heartwood darkens to a light brown and is occasionally
red tinged. It has a faint odor, good dimensional stability, and
is used for general joinery, foundry patterns, boxes and crates,
paneling and shelving.
Idaho White Pine (also called Western
White Pine) varies from nearly white to pale reddish brown and darkens
with exposure. It is famous for its workability across or with the
grain and is valued for joinery, foundry patterns, paneling, interior
trim, furniture, boxes and siding. It is the preferred species for
stage flooring in theaters. Availability is limited.
Mountain Hemlock and Alpine Fir
are distinguished from Western Hemlock and the other true firs by
having lower assigned design values, which is relevant only in structural
applications. When aesthetics are the primary consideration, refer
to the description under Hem-Fir. These species are light colored,
moderately strong, fine grained and ideally suited to interior paneling,
shelving, crafts and DIY projects, trim and fascia.
Western Red, Incense, Port Orford and Alaskan
Yellow cedars are grouped together for similar
performance properties. The heartwood of these species is naturally
durable against the harsh effects of exposure to the elements. They
are favorites for decks, siding, planters, fences, and other outdoor
amenities such as screened porches, greenhouses, pool-side structures,
arbors, and trellises. The sapwood of these species also pressure
treats well with preservatives for added durability.
Grades for cedar products can be very confusing to
the uninitiated because every purveyor seems to offer their own
grades. However, there are recognized standard and special grades
for cedar products. It is important for designers and specifiers
to learn the difference between ALSC-recognized grades (defined
by ALSC-accredited agencies), the proprietary grades defined through
buyer-seller agreements, and marketing names used primarily for
Refer to the Grades & Quality Control
section or the WWPA publication
Natural Wood Siding Technical Guide (TG-8). The
ALSC publishes a list of accredited agencies and, by permission
from ALSC, WWPA makes copies available to designers upon request.
(This is a list of accredited agencies, not grades and grade descriptions.)
Western Red Cedar is the largest and
most abundant of all cedars in managed forests. It is non-resinous
and has a strong spicy scent. Heartwood varies from dark reddish
brown to a pinkish color and has excellent weather-resistant properties.
Sapwood is light yellow. One of the lightest in weight of the commercially
important softwoods, it is often used for houseboats. It is valued
for paneling, decks, and greenhouses as well as for siding, posts,
fencing, shingles and shakes.
Incense Cedar has a famously spicy scent
and is widely available. Heartwood is light brown, frequently tinged
with red and is extremely durable. A highly workable wood, it machines
and weathers well. Used outdoors for amenities and landscaping applications,
it is also used for paneling, chests, louvers and pencils.
Port Orford Cedar is limited in supply
and availability. It grows only in a small area of southern Oregon
and northern California, and very limited amounts are harvested
from private lands and made available, usually only by request.
It is priced accordingly. It has a pungent, ginger-like scent, is
easily worked, and polishes well. In Japan, it is sometimes substituted
for Hinoki when appearance is critical. It is used for small items
such as woodenware, novelties and toys.
Alaskan (Yellow) Cedar is one of the
most beautiful of America's durable softwoods and is sometimes overlooked
in favor of more publicized species. However, it is reasonably abundant
from Alaska and Canada. It has a fine texture and straight grain,
and its nearly yellow color silvers exquisitely upon exposure. Strongly
aromatic, it is moderately strong and hard. It is used where weather
resistance, stability and workability are needed: bleachers, park
benches, exterior cabinet work, stage construction, and marine and
commercial landscape installations.
It is essential for designers to understand the differences
among Western species and which are best suited for intended applications.
Several WWPA publications are particularly helpful in this area:
Ponderosa Pine (FS-2), Douglas Fir-Larch (FS-3) and Hem-Fir
(FS-4) species facts publications and WWPA's Species Books,
Volumes 1, 2 and 3 with color photos of selected species and
grades. Refer to the Literature
section to order these and other publications.
(Note that selected tables will appear in a new browser window)
Species Marketing Categories - Stamps (species.pdf)
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. ©1997