C16, C24, D24 and D30), but properties can be declared directly, or by means of a user-defined strength class. Availability of large size and long length timbers should . It has the ability to hold nails and screws as well as glue. Douglas fir plywood comes in three basic grades. Products from trees growing west of the Cascade Crest are simply identified as “DF” on the grade stamp. It’s nearly as tough as nails! 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. 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. AB is as close to perfect as it comes. Despite the name “Douglas Fir,” the tree is actually part of the Hemlock family. 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. Sizes tested ranged from nominal 51 by 102 mm to 102 by 256 mm. When it comes to general strength, oak is also the winner, but fir is more workable. Construction grade Douglas Fir has an average “Extreme Fiber Stress in Bending, Fb” of est. 1 and No. Spruce. Other grades are designed for serviceability with strength and appearance qualities to provide reliable and economical construction. Modelling mechanical properties of spruce and Douglas fir timber by means of X-ray and grain angle measurements for strength grading purpose. Kiln-dried Douglas fir wood presents the number one choice for building a rafter-styled roof in a wood frame house. the grade stamp. For every knot present in a length of fir lumber, its strength drops by 5%. north American Douglas fir; spruce-pine-fir; Australian-grown plantation Pinus species, including slash, maritime, radiata and Caribbean pines. Both red oak and white oak are harder than Douglas-fir wood. 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 Stability. 10.1007/s00107-016-1149-4. DeltaMan. 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 is only moderately durable, and both sapwood and heartwood resist impregnation with preservatives. Douglas Fir is ideal for outdoor or indoor applications where strength is needed for a structural purpose. 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. 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. Tensile strengths of Douglas-fir and hem-fir were not sig- nificantly different. There has been little in-grade strength test data on timbers, due to the relatively small volume of timbers produced. Traditional stress grades (‘F’ grades) based on strength grouping. This tree grows prodigiously in the Pacific Northwest. The timber lacks termite-resistance and sapwood is susceptible to lyctid borer attack. Douglas Fir is one of Great Northern Lumber’s most plentiful softwood species, accounting for one fifth of our company’s softwood reserves. Outside of traditional timber framed structures, Douglas Fir wood has great applications in thinner stock sizes too. 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. 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. Durability: Douglas-fir heartwood is rated as Class 3 durability and can be used for above-ground purposes, but the sapwood is non-durable. always be confirmed with suppliers prior to specifying. No. 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. DFP is produced to the manufacturing standard CSA O121 Douglas fir plywood, where front and back faces are Douglas Fir. Douglas Fir, Ponderosa Pine, White Fir and Western Red Cedar are the most common single species sold as dimension lumber products. Douglas Fir, friend of the forester, sawmiller and woodworker alike but taken for granted in it’s own back yard! 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. in the Douglas Fir-Larch and Hem-Fir species combinations; however S-P-F and Northern species timbers are available only in smaller sizes. Overall Similarities. A perfect choice for outdoor patio covers, pergolas, or pavilions – either stained or painted. 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. 3 to 6 inches in diameter, were tested in third-point bending and in Compression parallel to the grain. 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. Understanding Douglas Fir's Strengths & Weaknesses. The stress grades and structural properties allocated to these species follow AS 1720.1 & AS 1720.2 1,2. Consider how a round log is converted into rectangular lumber. A strength class is simply a grade with associated numbers for strength, stiffness and density that can be used in design. Douglas Fir, Engelmann Spruce, and Southern Pine specimens were tested in a green condition to determine shear strength in members without checks and splits. Strength: Douglas Fir vs. Doug Fir lumber products are identified by region. 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. Lumber Yard Checklist. Douglas-fir is a large tree, reaching 85 metres on BC’s coast and 42 metres in the Interior. Doug Fir timbers are a growing breed of wood timbers for both interior and exterior applications in the Midwest. The moisture content at time of test was about 14 percent. 3. 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. What was also illustrated from the table of design values was that the strengths vary greatly with the grade of the wood. Both pine and Douglas fir are considered softwoods. Douglas Fir sapwood is whitish like pine. Grades are: SELECT STRUCTURAL No.1 & BTR (in Douglas Fir, Douglas Fir-Larch, or Hem-Fir species only.) 494 129 5. hal-01530963 Modelling mechanical properties of spruce and Douglas r timber by means of X-ray and grain angle … 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. Anything within the “Select” and “Finish” categories makes good flooring, trim, cabinets, and paneling. The oldest trees can be more than 1,500 years old. 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. Strength class is usually specified with reference to EN338 (e.g. Appearance and structural grades are very different so it is important to specify which is necessary for your particular project. In comparison to other species ranging from 1200 ~ 1500 for Select Structural grades. Coming from North West of America, DOUGLAS FIR is often used for reaforestation in France and in Europe. It can cope with heavy … DOUGLASFIRPLYWOOD (EighthEdition) COMMERCIALSTANDARDCS45-48 [SupersedesCS45-47] EffectiveDateforNewProductionFromNovemberI,1948 ARECORDEDVOLUNTARYSTANDARD … In estimating lower exclusion values, adjustments should be made for skewed distributions. Douglas Fir Pseudotsuga menziesii Douglas firs are among the tallest trees on the continent, second only to coastal redwoods. The wood passes lightness and tensile strength tests with flying colors. 2). Post Nov 18, 2016 #1 2016-11-18T02:48. 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. Since it is readily harvested in substantial quantities, the price is reasonable. 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