the material wood

“Crisscrossing light wood frame recalls Gothic and surrounding trees while lifting the mind skyward.” E. Fay Jones and Associates.

Thorncrown Chapel Eureka Springs, Arkansas 1980

WOOD

Qualities of Wood

• Strong & Stiff• Light• Easily worked / shaped• Fastened quickly &

economically• Recyclable• Biodegradable• Renewable Resource

Undesirable Characteristics of Wood

Not perfectly straight nor precise

Size & shape affected by moisture

Contains growth defects

Can spilt & warp

Burns easily

Decays

Susceptible to Insect Damage

Tree Composition

Bark

Cambium

Sapwood

Heartwood

Pith

Softwoods : Conifer Trees (pine, fir, spruce)for framing and sheathing

Hardwoods - Deciduous trees (leaf trees)Like maple, oak ash, beech, birch Used for Flooring, moldings, furniture

Tree Cells

Primarily Hollow, Cylindrical CellsAxis running parallel to the tree

(grain direction)Tough Cellulose bound by

Lignin

Impacts the properties of wood

Tree Growth

Springwood (earlywood)Faster growthCells larger and less dense

Summerwood (latewood)Slower growthCells smaller and denser

Types of Trees / Woods

Oak

Poplar

Pine

Construction Uses for Wood

Structural Framing

Subfloors and Roof Sheathing

Siding - Structural & Exposed

Finish cabinetry and Trim

Lumber Production - Sawing

Plain SawingMaximum Yield

Varying grain pattern

Common use - Framing

lumber

Lumber Production - Sawing

Quarter Sawing

Perpendicular to annual rings

Less yield, but consistent grain pattern

Improved wearing quality, less distortion

Typical Sawing Method

Lumber Drying

Drying MethodsAir

Kiln

Drying EffectsShrinkage

Reduced weight

Increase of strength and stiffness

More dimensional stable

DifferentialShrinkage

(between radial &tangential)

during dryingcan causedistortions

Lumber Surfacing

Purpose;Smooth

Dimensional precision

Designations; S2S, S4S

Surfacing typically performed

before or after drying?

Rough sawn(not surfaced)

S4S

Lumber Defects

Growth defectsKnots & knot holesDecay and/or insect damage

Manufacturing DefectsSplits & checksCrook, bow, Cup, and/or twist

Lumber Grade & Species

Graded by:Strength & Stiffness (Structural Lumber), or

Appearance (Finish Lumber)

Lumber sold by - Species and GradeBetter Grade Higher price

Scarce or Higher Quality Species Higher price

Spruce, Fir, or PineStud

Surfaced Dry

No 2 LumberKiln Dried (19% moisture)

Lumber Thickness and Width - NOMINAL

Thickness < 2 inches - Boards 2 to 4 in. - Dimension Lumber = to or > 5 inches - Timbers

Widths Framing Lumber - 2, 4, 6, 8, 10, 12 inchesFinish /lumber - 1 inch (typ.)

Lumber Thickness and Width - ACTUAL

Nominal not equal to Actual dimensions

Lumber SAWN Close to Nominal

Then dried and surfaced

Up to 6 inches - actual is 1/2 inch less

Greater than 6 inches - actual is 3/4 inch less

Lumber Lengths

Typically; Two (2) foot increments

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

Exceptions; 93 inch studsSpecial order lengths

Lumber Pricing Factors

Species

Grade (& drying process)

Lumber Size

Lumber Pricing Unit - Board Feet

One board foot = 1 inch X 12 inch X 1 foot

Calculation based upon Nominal dimensions

# of board feet =

[(thickness” X width”) / 12] X length’

Example; 2x8 that is 10 feet long

[(2x8)/12] X 10 = 13.33 board feet (bf)

Laminated Wood (Glulam)

Lamination Process

Why Laminate?Create a size not available naturallyCreate ShapesImprove Quality

Structural Composite Lumber (PSL)

Wood Panel Products

Why Panelize?More “controlled” productEfficient use of forest productsIncrease labor productivity

TypesPlywood panelsComposite panelsNonveneered panels

Veneered Panels - Plywood

Thin layers of veneer glued together

Odd number of veneers

Alternating direction of veneers

Face veneers parallel

Size: 4’x8’ panels

Thickness: ¼” to 1”

Veneer Grades

Based on the smoothness & integrity of the veneers

Classifications; A, B, C (plugged), C, D

Price Variances

C Grade

C Plugged

A Grade

Non-veneered Panels

Oriented Strand Board (OSB)

Waferboard

Particleboard

Fiberboard

Particleboard Fiberboard

Oriented Strand Board (OSB)

Long strand like wood particles

Alternate grain orientation (3-5 layers)

Compressed / glued

Strongest of the Non-veneered

Uses; Sheathing for floor, roofs, & siding

Waferboard & Particleboard

WaferboardLarge wafer-like particles - No orientationUses; Low moisture areas

ParticleboardSmall wood particles No orientationUses; Low moisture areas

Panel Standards & Grading

Established by American Plywood Association (APA)

Standards based on;Structural adequacyDimensional StabilityDurability of Adhesive

Structural Ratings

Specified by Thickness or Span Rating

Span Rating Grade StampFor veneered &

nonveneeredLong dimension

perpendicular to

the support

Exposure Durability Classifications

Exposure DurabilityExterior - siding or

continuous exposure Exposure I; waterproof

glue but lower quality veneers

Exposure II; protected environments & minimum wetting

PRESERVATIVE-TREATED WOOD

Waterborne PreservativesACQ (alkaline copper quatCA (copper azole)SBX (sodium borates)CCA (copper, chromate, arsenic)

CreosoteDistillate of coal tar

Oil-bornePenta(chlorophenol)

Wood Polymer Composite Planksproprietary name: TREX

Advantages:Decay ResistanceEasy Workability

Wood Fasteners

Nails

Wood & Lag Screws

Bolts

Toothed Plates

Sheet Metal & Metal Framing Devices

Machine Driven Staples & Nails

Adhesives

Nails

Sharpened metal pins

Installation: Hammer or

mechanical nail gun

Common Nails

Finish Nails

Other types

16d Galvanized

16d Sinker

Deformed Shank

10d Galv. Spiral

Finish Nail

Roofing Nail (far right)

NailsSize - Measured in pennies

CoatingsBright/ Plain uncoated steel

Galvanized Corrosion-resistant

Resin/Vinyl

Anchorage

Face, End, or Toe

Machine Driven Nails & Staples

Nail Guns, Staple guns

Pneumatic (or electric)

Pre-packaged fasteners (collated nails)

Improved Productivity

Used in many applications

Power actuated fasteners

Battery Powered Electric Nailer

Collated Nails

Wood Screws

Head type

Sizing - Gauge & Length

Installation

Holding power

Uses

Deck Screws

Types of ‘Heads’

Lag & Drywall Screws

Lag ScrewsLarge screwsSquare or octagonal headInstalled w/ wrench

Drywall screwsUsed to attach drywall

Bolts

Heavier structural connections

Sizes

TypesMachineCarriage

Washers

Toothed Plates

Sheet metal plate w/ numerous teeth

Used with roof & floor trussesPressed into members

Very effective fasteners

Sheet Metal Framing Devices

Light Wood Framing Joist Hangers Framing anchorsAngle anchorsRafter anchor

Heavy Timber or Laminated Framing

Adhesives

Widely used in the manufacture of wood productsWood panelsLaminated woodCabinetry

On Site UsesSheathing

Engineered Wood

Trusses

Wood I-Joists

Beams (gluelams)

Panel Components

Trusses

Types of Trusses - Floor & Roof

Floor Trusses Roof Trusses

Trusses (cont.)

Where and How Built?Most factory built (pre-

engineered)Most 2X4 or 2X6 w/ toothed

fasteners

Order how?SpanLoadsPitch (roof)Overhang

I-Joists

Uses

Sizes

Composition

Cost

Why Use Trusses or I-Joists?

Less material (less weight)

More efficient use of wood

Increased Span

Increased dimensional stability

Installation savings (labor)

Sustainability in Wood Construction

Only major renewable structural material

Forestry PracticesSustainable forestryClearcutting & replanting

Mill Practices – Lumber Recovery Factor (LRF)

Transportation

Embodies Energy Content