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 Western Species and End Uses


SECTION CONTENTS
Douglas Fir-Larch
Hem-Fir
Douglas Fir-South
Spruce-Pine-Fir (South)
Western Woods
Western Cedars


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 interchangeably.

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 Use Recommendations

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

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 and millwork.

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.

Spruce-Pine-Fir (South)

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 Dept.

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.

Western Woods

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 Western cedars.

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 wood windows.

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 Cedars

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 promotional purposes.

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.

 Information Tables
(Note that selected tables will appear in a new browser window)

Western 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 WWPA
 

 
 
 
    

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