Taxonomy of Wood Products

Solid Wood Products

Wood Products Taxonomy

Wood Products Taxonomy

Dimension Lumber

“2 by 4”, “2 by 6”, “2 by 8” construction lumber Majority of lumber produced in North America Production grew approx. 1.4% p.a. from 1985-2005Bulk commodity product with little specializationUsed mainly in residential construction

Dimension lumber - sizes4.

0”

3.7”

3.5”

2.0” 1.7” 1.5”

Rough sawn After drying After planing(“nominal” size) (actual size)

“Two by four”

Dimension Lumber - sizes• Thickness – increments of 2 inches• Width – increments of 2 inches• Length – increments of 2 feet

Product Length (ft)

8 10 12 14 16 18 20

2 x 4 215 245 245 240 270 260 270

2 x 6 215 245 240 235 265 260 270

2 x 8 220 240 255 240 275 270 290

2 x 10 195 200 290 300 300 315 300

Premiums for larger cross-section dimensions and lengths.

Softwood lumber pricing (US$/MBF)

Dimension Lumber

Dimension Lumber

• Majority of production sold in US• SPF species group (Spruce - Pine – Fir)

Softwood Boards

Non-structural, finished product

1” thick material, 2” width increments, 2’ length increments

Markets are: export, industrial, home centres

BC Wood Specialties

Softwood boards

Wall panellingCanadian softwood board species

Softwood boards

Decorative panelling Furniture

Timber

Minimum dimensions 5.5”High value productMajority goes to export markets Production is decreasing

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• Post and beam construction

• Architectural value as well as structural role• Higher value product than smaller dimensions ($/m3)

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Solid softwood lumber – species

Boards Dimension lumber TimberSpruce SPF Douglas-firDouglas-fir Douglas-fir HemlockPines HemlockHemlockCedars

Machine Stress Rated Lumber

Lumber is graded by machine rather than manually Uses non-destructive measurement of stiffness to predict strength of lumber pieces Structural end-uses Value-added lumber product Trusses are large market

Top chord Web

Truss plateBottom chord

Bending test

Deflection

Load

Maximum load

Modulus of RuptureMOR“strength”

Linear portion of curve

Modulus of ElasticityMOE“stiffness”

MOE – MOR relationship

MOE“stiffness”

MOR“strength” x

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MOE measured

MOR predicted

Machine Stress Rated Lumber

Rollers Sensor

Load cell Lumber

MSR lumber in roof trusses

Softwood lumber prices

Prices in $US per thousand board feet (Mfbm)(2x4, random lengths)

• SPF, #2 and better $ 372• D-fir, #2 and better $ 420• SPF, 1650f $ 405• SPF, 1800f $ 425• SPF, 2100f $ 435• SPF, 2400f $ 450

Wood Products Taxonomy

e.g. dimension lumber trim ends

Short lengths Longer lengths

defect, e.g. knots

Removal of defects

Butt joint (end grain)

Finger Joined Lumber

Longer lengths produced from shorter stock

Allow defects to be reduced

End-to-end joints via side-grain gluing

Finger Jointed Lumber

BC Wood Specialties www.ufpi.com

Structural or non-structural joints can be made

Longer fingers → greater strengths

Increased dimensional stability in resulting piece

Utilized in lumber, glulam, I-beams

Finger joints

Narrower edge

Wider face

Dimensional stability of finger joined lumber

Warping tendency of any one piece is randomized in its location in finger-joined lumber and resulting piece is more dimensionally stable.

Edge-glued Panels

Edge-lamination of wood Greater widths from narrow material Dimensionally stable-panel produced Industrial and finished retail products

Wood dryng defects

• Tangential shrinkage > Radial shrinkage• Natural tendency to “cup”• Cupping is greater in wider pieces of wood

RT

T

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Dimensional stability of edge-glued panels

Randomization of end grain patterns

Less likely to cup

Edge-glued panels

Wood Products Taxonomy

Treated Wood

Preserves the wood against fungal degradation For wood used in external conditions Effectively poisons the wood Chemical agent is either water-borne or oil-borne Usually introduced into wood using pressure treatment

Treated WoodExamples of preservatives

Creosote

Pentachlorophenol (PCP)

Chromated copper arsenate (CCA)

Ammoniacal copper quaternary (ACQ)

Treated WoodPressure treatment vessels

Treated WoodExamples of preservative use

Creosote

Pentachlorophenol (PCP)

Treated WoodExamples of preservative use

CCAACQ

Pressure-treated Wood

The retention of wood preservatives in wood species which do not readily abosrb the preservative chemical can be enhanced by incising the wood.

Non-incised lumber Incised lumber

Wood Products Taxonomy

Hardwood Lumber

Visual appearance of lumber is key

Used for decorative and architectural purposes rather than structural products

Flooring, trim & molding, joinery, cabinets, furniture

Hardwood Lumber

Hardwood Lumber

Grading system based on cutting high quality boards from rough lumber.

• Thickness – usually 1 inch (but also other thicknesses)• Width – random widths• Length – increments of 1 foot

Lumber GradingSoftwood vs. Harwoods

Lumber Grading - softwoods

• Softwood grading considers that the piece of lumber will be used as it stands and will not undergo subsequent reprocessing.

• Therefore the greatest defect in the piece decides the grade of that piece of lumber.

Lumber Grading - harwoods

• Hardwood boards are graded on the amount of clear (defect-free) wood that can be obtained after the removal of defects.

• The boards are either “ripped” along the grain, or “chopped” across the grain to produce smaller, clear pieces are called “cuttings”.

• Cuttings are then used in the production of other items such as edge-glued panels or furniture.

Boards

Dimension Lumber

Timber

Machine Stress Rated Lumber

Solid softwood lumber

Finger Jointed lumberEdge-glued Panels

Treated WoodHardwood

Other solid lumber products