Download - 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