Post Nov 18, 2016 #1 2016-11-18T02:48. Consider how a round log is converted into rectangular lumber. Due to its strength, it is used for building and construction, and is one of the finest timbers for heavy structural purposes, including glulam beams and roof trusses. The timber cannot be pressure treated with copper, chromium and arsenic (CCA), but can be boron treated to Hazard Classes H3.1 and H1.2. I wouldn’t be surprised that most of the 3/4″ x 3 1/2″ boards are mostly sapwood. Thanks to their high-quality appearance, predictable strength, and reasonable price point, they are an excellent fit for your big timber needs. This tree grows prodigiously in the Pacific Northwest. It can cope with heavy … Douglas fir is commonly found as sawn timber in weather-protected heavy construction applications such as mining timbers, posts and poles. Construction grade Douglas Fir has an average “Extreme Fiber Stress in Bending, Fb” of est. In estimating lower exclusion values, adjustments should be made for skewed distributions. No. in the Douglas Fir-Larch and Hem-Fir species combinations; however S-P-F and Northern species timbers are available only in smaller sizes. Inland, Douglas Fir often grows in stands with Western Larch which shares similar structural performance characteristics. AB is as close to perfect as it comes. Both pine and Douglas fir are considered softwoods. The Janka rating for red oak, the softer of the two oaks, is 1,220 pounds-force, while that for Douglas-fir is only 620, which is a little more than half. In comparison to other species ranging from 1200 ~ 1500 for Select Structural grades. 3 to 6 inches in diameter, were tested in third-point bending and in Compression parallel to the grain. Douglas-fir lumber was sampled from sawmills in British Columbia in two sizes (nominal 2 x 4 and 2 x 8) and two grades (select structural and No. Sizes tested ranged from nominal 51 by 102 mm to 102 by 256 mm. The prices paid for top grade Douglas fir result form the extensive harvesting of the last of the old growth forests in Western North America. Understanding Douglas Fir's Strengths & Weaknesses. Pseudotsuga Menziessii is the latin name for Douglas Fir which originates from USA and Canada, this is also grown in the UK, New Zealand and Australia. Strength: Douglas-fir is an excellent framing timber. Stability. Properties of european planted trees (young and with a rapid growth) which are mentionned in this sheet are different from those of the "Oregon pine" (old and with a slow growth) coming from its original growing area. Both red oak and white oak are harder than Douglas-fir wood. A quick-reference checklist for a smooth trip to the lumber yard. It has the ability to season well in place because of its natural dimensional stability. A strength class is simply a grade with associated numbers for strength, stiffness and density that can be used in design. In the same way, there are also a number of varieties of fir, including hemlock fir, which can affect your decision differently if you are thinking about hem fir vs. pine. Strength class is usually specified with reference to EN338 (e.g. Lumber Yard Checklist. AltruFir’s CVG Douglas fir flooring is a C & BTR grade, and is characterized by having 10-25 rings per inch and knots no larger than ¾” in diameter. Douglas Fir, friend of the forester, sawmiller and woodworker alike but taken for granted in it’s own back yard! C16, C24, D24 and D30), but properties can be declared directly, or by means of a user-defined strength class. East of the Cascades, Larch grows intermixed with Doug Fir and marketed as “DF-L”. Plywood Grades Douglas fir plywood (DFP) and Canadian so wood plywood (CSP) are the most common types of plywood used in construction applications throughout Canada, whereas poplar plywood is less common. 494 129 5. What was also illustrated from the table of design values was that the strengths vary greatly with the grade of the wood. Kiln-dried Douglas fir wood presents the number one choice for building a rafter-styled roof in a wood frame house. The timber lacks termite-resistance and sapwood is susceptible to lyctid borer attack. Listed under tables of the unit weights and under the design values of specific species, several possibilities were noted, particularly a few of the pines, Yellow Poplar, and Douglas Fir. Douglas fir plywood comes in three basic grades. It’s nearly as tough as nails! Other grades are designed for serviceability with strength and appearance qualities to provide reliable and economical construction. Douglas fir works well with power tools and can be painted or stained as needed. DFP is produced to the manufacturing standard CSA O121 Douglas fir plywood, where front and back faces are Douglas Fir. Outside of traditional timber framed structures, Douglas Fir wood has great applications in thinner stock sizes too. Douglas Fir Specification. Douglas Fir, Ponderosa Pine, White Fir and Western Red Cedar are the most common single species sold as dimension lumber products. One method is suggested. Timbers Douglas Fir timbers are a great choice when large structural beams are required. the grade stamp. A perfect choice for outdoor patio covers, pergolas, or pavilions – either stained or painted. Douglas Fir Timbers. 10.1007/s00107-016-1149-4. Tensile strengths of Douglas-fir and hem-fir were not sig- nificantly different. Douglas Fir sapwood is whitish like pine. European Journal of Wood and Wood Products, Springer Verlag, 2017, 75 (4), pp.527-541. 2 Grade of Douglas fir and maximum span floor joists - imperial units; Nails and Spikes - Withdrawal Force - Allowable withdrawal load for nail and spikes; Softwood and Hardwood - Structural Strength Classes - Strength classes, bending stress and mean density of hardwood and softwood For every knot present in a length of fir lumber, its strength drops by 5%. The most common framing grade is #2 and the most common uses are for rafters, joists, studs and posts. Douglas fir is only moderately durable, and both sapwood and heartwood resist impregnation with preservatives. Structural Joists & Planks (2x5 through 4x18, intended for engineering applications for lumber 5" and wider, such as floor and ceiling joists, rafters, headers, small beams, trusses and general framing applications. Products from trees growing west of the Cascade Crest are simply identified as “DF” on the grade stamp. Douglas Fir, Engelmann Spruce, and Southern Pine specimens were tested in a green condition to determine shear strength in members without checks and splits. 3. Some grades are selected for appearance and strength. Doug Fir lumber products are identified by region. Douglas Fir is graded to C24, the timber is moderatly durable with a medium resistance to shock loads and it has a high bending strength. The oldest trees can be more than 1,500 years old. The moisture content at time of test was about 14 percent. Additional tests were conducted on air-dried solid-sawn Douglas Fir and Southern Pine specimens. Coming from North West of America, DOUGLAS FIR is often used for reaforestation in France and in Europe. Anything within the “Select” and “Finish” categories makes good flooring, trim, cabinets, and paneling. north American Douglas fir; spruce-pine-fir; Australian-grown plantation Pinus species, including slash, maritime, radiata and Caribbean pines. Traditional stress grades (‘F’ grades) based on strength grouping. There has been little in-grade strength test data on timbers, due to the relatively small volume of timbers produced. Douglas Fir is the strongest of our homegrown softwoods. 1 and No. 494 129 5. Douglas fir is recognized for its superior strength-to-weight ratio and has the highest ratings of any western softwood for extreme fiber stress in bending. B & BTR is not commonly sold in the U.S., as there is little market for it, but it is available. strength is the primary factor, Douglas Fir meets all requirements, and its straightness, ease of fabrication and availability in a wide range of sizes and stress grades furnish bonus qualities. Douglas Fir is ideal for outdoor or indoor applications where strength is needed for a structural purpose. Douglas Fir is one of the most widely used species for framing due to its strength, dimensional stability and its availability. always be confirmed with suppliers prior to specifying. Appearance and structural grades are very different so it is important to specify which is necessary for your particular project. Doug Fir timbers are a growing breed of wood timbers for both interior and exterior applications in the Midwest. Maximum Floor Joist Span - No. Throughout the learning curve that J. Gibson McIlvain has gone through in our decade-long relationship with carrying softwoods, we’ve come to understand the up sides and down sides of using Douglas Fir. Douglas Fir timber is often grade by structural grades but it can also be had in appearance grades for projects where the frame will be visible. Douglas Fir is one of Great Northern Lumber’s most plentiful softwood species, accounting for one fifth of our company’s softwood reserves. Douglas-fir is a large tree, reaching 85 metres on BC’s coast and 42 metres in the Interior. Grades are: SELECT STRUCTURAL No.1 & BTR (in Douglas Fir, Douglas Fir-Larch, or Hem-Fir species only.) It has the ability to hold nails and screws as well as glue. As a framing species, Douglas Fir offers strength, excellent nail holding power and outstanding dimensional stability. Modelling mechanical properties of spruce and Douglas fir timber by means of X-ray and grain angle measurements for strength grading purpose. The difference in strength between any of these pines and Douglas-fir is not so great but that low density pieces of the one species are weaker than the average for the other species. As far as strength properties are concerned, the choice between any two lots of southern pine and Douglas -fir will depend upon the grade and density of the timber composing each lot. DeltaMan. More than 5 knots and the lumber will not make top grade and will downgraded to construction grade, which is of course worth considerably less money. 1800 ~ 2800. When it comes to general strength, oak is also the winner, but fir is more workable. The hardness and strength factors will differ a bit if you are considering Douglas fir vs. eastern white pine or Ponderosa pine vs. Douglas fir. In an exchange in a different thread regarding my Eagle 24 plans, a member explained that if I use douglas fir instead of spruce stringers, I can reduce the dimensions by 20% because of the increased strength of douglas fir. Spruce. Despite the name “Douglas Fir,” the tree is actually part of the Hemlock family. The stress grades and structural properties allocated to these species follow AS 1720.1 & AS 1720.2 1,2. DeltaMan. The grade is: STUD. Availability of large size and long length timbers should . Douglas Fir Pseudotsuga menziesii Douglas firs are among the tallest trees on the continent, second only to coastal redwoods. Its tight knot structure and close grain make it as beautiful as it is functional, with appearance grades available in both clear and tight knot. Douglas Fir is an excellent construction grade lumber utilized for strength and apperance purposes. Douglas-fir and ponderosa pine tapered logs David W. Green Thomas M. Gorman James W. Evans Joseph F. Murphy Cherilyn A. Hatfield I Abstract Approximately 375 Douglas-fir and ponderosa pine logs. The wood passes lightness and tensile strength tests with flying colors. Pros. DOUGLASFIRPLYWOOD (EighthEdition) COMMERCIALSTANDARDCS45-48 [SupersedesCS45-47] EffectiveDateforNewProductionFromNovemberI,1948 ARECORDEDVOLUNTARYSTANDARD … 2). Since it is readily harvested in substantial quantities, the price is reasonable. 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