Chapter 3Wood

Qualities of WoodQualities of Wood

THE MATERIAL WOOD ISTHE MATERIAL WOOD IS::

StrongStrong

LightLight

Easily handled, worked, & Easily handled, worked, & shapedshaped

Fastened quickly & Fastened quickly & economicallyeconomically

RecyclableRecyclable

BiodegradableBiodegradable

A renewable resourceA renewable resource

Undesirable Characteristics of WoodUndesirable Characteristics of Wood

Not perfectly straightNot perfectly straight

Affected by moistureAffected by moisture

Has growth defectsHas growth defects

But can be protected from:But can be protected from:Splitting & warpingSplitting & warping

BurningBurning

DecayingDecaying

Attack by Insects Attack by Insects

Tree CompositionTree Composition

BarkBark

CambiumCambium

SapwoodSapwood

HeartwoodHeartwood

PithPith

Tree GrowthTree Growth

Springwood Springwood (earlywood)(earlywood)– Faster growthFaster growth– Cells larger and less denseCells larger and less dense

SummerwoodSummerwood (latewood)(latewood)– Slower growthSlower growth– Cells smaller and denserCells smaller and denser

TWO TYPES OF WOODTWO TYPES OF WOOD

Generally, two types of trees provide Generally, two types of trees provide wood:wood:

HARDWOOD is produced by trees that have HARDWOOD is produced by trees that have broad leaves - lose them in winter - reproduce broad leaves - lose them in winter - reproduce them in spring. Species are oak, pecan, them in spring. Species are oak, pecan, walnut, ash, cherry, birch, etc. Slow growth.walnut, ash, cherry, birch, etc. Slow growth.

SOFTWOOD is the type that comes from trees SOFTWOOD is the type that comes from trees that have needles, are evergreen, do not lose that have needles, are evergreen, do not lose them in winter. Species include pine, fir, them in winter. Species include pine, fir, spruce, larch, cedar, etc. Fast growth. Much spruce, larch, cedar, etc. Fast growth. Much more plentiful than hardwoods.more plentiful than hardwoods.

Construction Uses for WoodConstruction Uses for Wood

Structural FramingStructural Framing

Subfloors and Roof SheathingSubfloors and Roof Sheathing

Finish Siding ( generally all softwood)Finish Siding ( generally all softwood)

Finish cabinetry, trim, & paneling Finish cabinetry, trim, & paneling

(generally hardwood(generally hardwood))

How Logs are Cut (softwoods) How Logs are Cut (softwoods)

Plain SlicedPlain Sliced

– Maximum YieldMaximum Yield

– Varying grain patternVarying grain pattern

– Common use - Framing Common use - Framing

lumberlumber

Aesthetic Use (hardwoods)Aesthetic Use (hardwoods)

Quarter SawingQuarter Sawing

– Perpendicular to annual ringsPerpendicular to annual rings

– Less yield, but consistent grain Less yield, but consistent grain pattern for appearancepattern for appearance

– Improved wearing quality, less Improved wearing quality, less distortiondistortion

Lumber Must be Dried for StabilityLumber Must be Dried for Stability

Drying MethodsDrying Methods– Kiln – heated in an oven to drive out moisture (much Kiln – heated in an oven to drive out moisture (much

less time, more costly, most stable)less time, more costly, most stable)

– Air - left to dry in the sun and air (long time, less Air - left to dry in the sun and air (long time, less costly, less control of dimension changes)costly, less control of dimension changes)

Drying EffectsDrying Effects– ShrinkageShrinkage

– Reduced weightReduced weight

– Increase of strength and stiffnessIncrease of strength and stiffness

– More stable dimensionallyMore stable dimensionally

Lumber SurfacingLumber Surfacing

Purpose:Purpose:

– Smooth surfacesSmooth surfaces

– Dimensional precisionDimensional precision

Designations; S2S, S4S, S2EDesignations; S2S, S4S, S2E

– Surface two sides, edges roughSurface two sides, edges rough

– Surface 4 sidesSurface 4 sides

– Surface two edgesSurface two edges

Surfacing is performed after performed after

material is driedmaterial is dried

Rough sawn(not surfaced)

S4S

Lumber DefectsLumber Defects

Growth defectsGrowth defects– Knots Knots – Decay and insect damageDecay and insect damage

Manufacturing DefectsManufacturing Defects– Splits & checksSplits & checks– Crook, bow, Crook, bow, – Cup, twist, tangoCup, twist, tango

Lumber Grade & SpeciesLumber Grade & Species

Graded According ToGraded According To::Strength & Stiffness (Structural Lumber)Strength & Stiffness (Structural Lumber)

Appearance (Finish Lumber)Appearance (Finish Lumber)

Lumber sold byLumber sold by - Species and Grade - Species and GradeBetter Grade Better Grade Higher price Higher price

Scarce or Higher Quality Species Scarce or Higher Quality Species Higher price Higher price

Building Codes & Architectural SpecificationsBuilding Codes & Architectural Specifications

will define permitted material strength characteristics, will define permitted material strength characteristics, which are defined by the lumber grading system. which are defined by the lumber grading system.

Spruce, Fir, or PineStud

Surfaced Dry

No 2 LumberKiln Dried (19% moisture)

Considerations That Affect StrengthConsiderations That Affect Strength

Primary Considerations:Primary Considerations:– SpeciesSpecies– GradeGrade– Direction of Load Vs. GrainDirection of Load Vs. Grain

– Grading of lumber is generally done with Grading of lumber is generally done with softwood material to be used structurallysoftwood material to be used structurally. . Hardwoods are basically a material used for Hardwoods are basically a material used for appearance and durability, and are not graded appearance and durability, and are not graded for structural characteristics.for structural characteristics.

Lumber Size Nomenclature – NOMINAL SIZELumber Size Nomenclature – NOMINAL SIZE

Thickness Thickness – Less than 2 inches – Boards Less than 2 inches – Boards

& Planks& Planks– 2 to 4 in. - Dimension Lumber2 to 4 in. - Dimension Lumber– 5 inches or more - Timbers5 inches or more - Timbers

Nominal Standard SizeNominal Standard Size – Framing Lumber - 2, 4, 6, 8, 10, Framing Lumber - 2, 4, 6, 8, 10,

12 inches (softwood)12 inches (softwood)– Finish lumber (hardwood) no Finish lumber (hardwood) no

standard widths, but finish standard widths, but finish thickness ¾”, 1”, 5/4”, 6/4” thickness ¾”, 1”, 5/4”, 6/4”

Lumber Thickness and Width - ACTUALLumber Thickness and Width - ACTUAL

Structural Lumber is Structural Lumber is rough cutrough cut to nominal to nominal dimensions, 2”x4”, 2”x6”, etc. After drying it is dimensions, 2”x4”, 2”x6”, etc. After drying it is surfaced to specific finish dimensions:surfaced to specific finish dimensions:

Up to 6 inches nominal – Up to 6 inches nominal – actual finish is 1/2 inch actual finish is 1/2 inch lessless. A 2”x4” is actually 1 ½” x 3 ½”.. A 2”x4” is actually 1 ½” x 3 ½”.

More than 6 inches nominal – More than 6 inches nominal – actual finish is 3/4 actual finish is 3/4 inch lessinch less. An 8” x 12” member is actually 7 ¼” x . An 8” x 12” member is actually 7 ¼” x 11 ¼”11 ¼”

Hardwood materials do not follow the same rulesHardwood materials do not follow the same rules..

Standard Framing Lumber LengthsStandard Framing Lumber Lengths Typically, framing lumber is available in Typically, framing lumber is available in increment lengths of two feetincrement lengths of two feet, such as, such as

8’, 10’, 12’, 14’, & 16’ (longer available)8’, 10’, 12’, 14’, & 16’ (longer available)

Exceptions:Exceptions: – 93 inch studs – precut for framing walls with 93 inch studs – precut for framing walls with

standard 8’ ceiling heightsstandard 8’ ceiling heights– Special order lengths include those that might not Special order lengths include those that might not

be economically feasible for a lumber dealer to be economically feasible for a lumber dealer to keep in stock.keep in stock.

Lumber Pricing Unit - Board FeetLumber Pricing Unit - Board Feet

Lumber, including softwood and hardwood is Lumber, including softwood and hardwood is typically measured in quantity in terms of typically measured in quantity in terms of “board “board feet.”feet.”

One board foot = One board foot = 1 inch x 12 inch x 1 foot1 inch x 12 inch x 1 foot

Calculations are based upon Calculations are based upon nominal nominal dimensions;dimensions;number of board feet = number of board feet =

[(thickness” x width”) / 12] x length in feet.[(thickness” x width”) / 12] x length in feet.

Example; 2x8 that is 10 feet longExample; 2x8 that is 10 feet long [ (2x8)/12 ] x 10 = 13.33 board feet.[ (2x8)/12 ] x 10 = 13.33 board feet.

Wood Panel ProductsWood Panel Products

Why Panelize?Why Panelize?– More “controlled” productMore “controlled” product– Efficient use of forest productsEfficient use of forest products– Increase labor productivityIncrease labor productivity

TypesTypes– Plywood panelsPlywood panels– Composite panelsComposite panels– Non veneered panelsNon veneered panels

Veneered Panels - PlywoodVeneered Panels - Plywood

Thin layers of veneer glued togetherThin layers of veneer glued together

Odd number of veneersOdd number of veneers

Alternating direction of veneersAlternating direction of veneers

Face veneers parallelFace veneers parallel

Size: 4’x8’ panelsSize: 4’x8’ panels

Thickness: ¼” to 1” Thickness: ¼” to 1”

Plywood came intoPlywood came into

wide use in the 1950swide use in the 1950s

because of increasebecause of increase

in labor cost.in labor cost.

Non-veneered PanelsNon-veneered Panels

Oriented Strand Board (OSB)Oriented Strand Board (OSB)

WaferboardWaferboard

ParticleboardParticleboard

FiberboardFiberboard

Particleboard

Fiberboard

Oriented Strand Board (OSB)Oriented Strand Board (OSB)

Has long strand-like wood particlesHas long strand-like wood particles

Grain orientation alternates (3-5 layers)Grain orientation alternates (3-5 layers)

Glued and compressedGlued and compressed

Strongest of the Non-veneeredStrongest of the Non-veneered

Uses; Sheathing for floor, roofs, & sidingUses; Sheathing for floor, roofs, & siding

Plywood Compared To OSBPlywood Compared To OSB

According to the “Georgia Pacific According to the “Georgia Pacific Corporation” the largest producer of panel Corporation” the largest producer of panel products:products:1994-19951994-1995– Plywood Production was 19 billion square Plywood Production was 19 billion square

feet and decliningfeet and declining– OSB Production was 10 billion square feet OSB Production was 10 billion square feet

and increasingand increasing1999 - OSB began to outsell plywood.1999 - OSB began to outsell plywood.Reason? Plywood is made of all new Reason? Plywood is made of all new material. OSB is made of scraps. Price of material. OSB is made of scraps. Price of OSB is much less for comparable use.OSB is much less for comparable use.

Waferboard & ParticleboardWaferboard & Particleboard

Waferboard - weak materialWaferboard - weak material– Large wafer-like particles - No orientationLarge wafer-like particles - No orientation– Uses; Low moisture areasUses; Low moisture areas

Particleboard - weak materialParticleboard - weak material– Small wood particles Small wood particles – No orientationNo orientation– Uses; Low moisture areasUses; Low moisture areas

Both products are inferiorBoth products are inferior

where strength is requiredwhere strength is required

and moisture is present.and moisture is present.

Wood Polymer Composite PlanksWood Polymer Composite Planks

““Artificial Wood” not in wide general use because Artificial Wood” not in wide general use because it is new and untested. Probably will be used it is new and untested. Probably will be used extensively in the future because of its stability, extensively in the future because of its stability, durability to weather, and resistance to insects.durability to weather, and resistance to insects.

Advantages:Advantages:– Decay ResistanceDecay Resistance– Easy WorkabilityEasy Workability

Wood FastenersWood Fasteners

NailsNails

Wood & Lag ScrewsWood & Lag Screws

BoltsBolts

Toothed PlatesToothed Plates

Sheet Metal & Metal Framing DevicesSheet Metal & Metal Framing Devices

Machine Driven Staples & NailsMachine Driven Staples & Nails

AdhesivesAdhesives

16d Galvanized

16d Sinker

Deformed Shank

10d Galv. Spiral

Finish Nail

Roofing Nail (far right)

Standard Sizes of Common NailsStandard Sizes of Common Nails

Machine Driven Nails & StaplesMachine Driven Nails & Staples

Nail Guns, Staple gunsNail Guns, Staple guns– Pneumatic (compressed air)Pneumatic (compressed air)– Electric AC powerElectric AC power– Battery operatedBattery operated

Pre-packaged fastenersPre-packaged fasteners– Collated nail packsCollated nail packs– StaplesStaples

Battery Powered Electric Nailer

Collated Nails

Wood ScrewsWood Screws Head typeHead type

Sizing - Sizing - – Gauge & LengthGauge & Length

InstallationInstallation

Holding powerHolding power

UsesUses

Drywall screws Drywall screws

Deck Screws

Types of ‘Heads’

Lag ScrewsLag Screws

Lag ScrewsLag Screws– Large screwsLarge screws– Square or octagonal Square or octagonal

headhead– Installed with wrench Installed with wrench

BoltsBolts

Heavier structural connectionsHeavier structural connections

TypesTypes– MachineMachine– CarriageCarriage

WashersWashers

Toothed PlatesToothed PlatesSheet metal plate punched to form Sheet metal plate punched to form numerous teethnumerous teeth

Used with roof & floor trussesUsed with roof & floor trusses

Machine pressed into membersMachine pressed into members

Sheet Metal Framing AnchorsSheet Metal Framing Anchors

Used mostly in light Used mostly in light Wood Framing asWood Framing as– Joist Hangers Joist Hangers – Framing anchorsFraming anchors– Angle anchorsAngle anchors– Rafter anchorRafter anchor

Limited Use with Limited Use with Heavy Timber or Heavy Timber or Laminated FramingLaminated Framing

AdhesivesAdhesives

Widely used in the manufacture of Widely used in the manufacture of wood productswood products– Wood panelsWood panels– Laminated woodLaminated wood– CabinetryCabinetry

On Site UsesOn Site Uses– Sheathing Sheathing – Floor deckingFloor decking