Chapter 3 Wood

Qualities of Wood THE MATERIAL WOOD IS: StrongLight Easily handled, worked, & shaped Fastened quickly & economically RecyclableBiodegradable A renewable resource

Undesirable Characteristics of Wood Not perfectly straight Affected by moisture Has growth defects But can be protected from: Splitting & warping BurningDecaying Attack by Insects

Tree Composition BarkCambiumSapwoodHeartwoodPith

Tree Growth Springwood (earlywood) –Faster growth –Cells larger and less dense Summerwood (latewood) –Slower growth –Cells smaller and denser

TWO TYPES OF WOOD Generally, two types of trees provide wood: HARDWOOD is produced by trees that have broad leaves - lose them in winter - reproduce them in spring. Species are oak, pecan, walnut, ash, cherry, birch, etc. Slow growth. SOFTWOOD is the type that comes from trees that have needles, are evergreen, do not lose them in winter. Species include pine, fir, spruce, larch, cedar, etc. Fast growth. Much more plentiful than hardwoods.

Construction Uses for Wood Structural Framing Subfloors and Roof Sheathing Finish Siding ( generally all softwood) Finish cabinetry, trim, & paneling (generally hardwood)

How Logs are Cut (softwoods) Plain Sliced –Maximum Yield –Varying grain pattern –Common use - Framing lumber

Aesthetic Use (hardwoods) Quarter Sawing –Perpendicular to annual rings –Less yield, but consistent grain pattern for appearance –Improved wearing quality, less distortion

Lumber Must be Dried for Stability Drying Methods –Kiln – heated in an oven to drive out moisture (much less time, more costly, most stable) –Air - left to dry in the sun and air (long time, less costly, less control of dimension changes) Drying Effects –Shrinkage –Reduced weight –Increase of strength and stiffness –More stable dimensionally

Lumber Surfacing Purpose: –Smooth surfaces –Dimensional precision Designations; S2S, S4S, S2E –Surface two sides, edges rough –Surface 4 sides –Surface two edges performed after material is dried Surfacing is performed after material is dried Rough sawn (not surfaced) S4S

Lumber Defects Growth defects –Knots –Decay and insect damage Manufacturing Defects –Splits & checks –Crook, bow, –Cup, twist, tango

Lumber Grade & Species Graded According To: Strength & Stiffness (Structural Lumber) Appearance (Finish Lumber) Lumber sold by - Species and Grade Better Grade  Higher price Scarce or Higher Quality Species  Higher price Building Codes & Architectural Specifications will define permitted material strength characteristics, which are defined by the lumber grading system.

Spruce, Fir, or Pine Stud Surfaced Dry No 2 Lumber Kiln Dried (19% moisture)

Considerations That Affect Strength Primary Considerations: –Species –Grade –Direction of Load Vs. Grain –Grading of lumber is generally done with softwood material to be used structurally. Hardwoods are basically a material used for appearance and durability, and are not graded for structural characteristics.

Lumber Size Nomenclature – NOMINAL SIZE Thickness – Less than 2 inches – Boards & Planks – 2 to 4 in. - Dimension Lumber – 5 inches or more - Timbers Nominal Standard Size –Framing Lumber - 2, 4, 6, 8, 10, 12 inches (softwood) –Finish lumber (hardwood) no standard widths, but finish thickness ¾”, 1”, 5/4”, 6/4”

Lumber Thickness and Width - ACTUAL Structural Lumber is rough cut to nominal dimensions, 2”x4”, 2”x6”, etc. After drying it is surfaced to specific finish dimensions: Up to 6 inches nominal – actual finish is 1/2 inch less. A 2”x4” is actually 1 ½” x 3 ½”. More than 6 inches nominal – actual finish is 3/4 inch less. An 8” x 12” member is actually 7 ¼” x 11 ¼” Hardwood materials do not follow the same rules.

Standard Framing Lumber Lengths Typically, framing lumber is available in increment lengths of two feet, such as 8’, 10’, 12’, 14’, & 16’ (longer available) Exceptions: –93 inch studs – precut for framing walls with standard 8’ ceiling heights –Special order lengths include those that might not be economically feasible for a lumber dealer to keep in stock.

Lumber Pricing Unit - Board Feet Lumber, including softwood and hardwood is typically measured in quantity in terms of “board feet.” One board foot = 1 inch x 12 inch x 1 foot Calculations are based upon nominal dimensions; 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 long [ (2x8)/12 ] x 10 = board feet. [ (2x8)/12 ] x 10 = board feet.

Wood Panel Products Why Panelize? –More “controlled” product –Efficient use of forest products –Increase labor productivity Types –Plywood panels –Composite panels –Non veneered 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” Plywood came into wide use in the 1950s wide use in the 1950s because of increase because of increase in labor cost. in labor cost.

Non-veneered Panels Oriented Strand Board (OSB) WaferboardParticleboardFiberboard Particleboard Fiberboard

Oriented Strand Board (OSB) Has long strand-like wood particles Grain orientation alternates (3-5 layers) Glued and compressed Strongest of the Non-veneered Uses; Sheathing for floor, roofs, & siding

Plywood Compared To OSB According to the “Georgia Pacific Corporation” the largest producer of panel products: According to the “Georgia Pacific Corporation” the largest producer of panel products: –Plywood Production was 19 billion square feet and declining –OSB Production was 10 billion square feet and increasing OSB began to outsell plywood. Reason? Plywood is made of all new material. OSB is made of scraps. Price of OSB is much less for comparable use.

Waferboard & Particleboard Waferboard - weak material –Large wafer-like particles - No orientation –Uses; Low moisture areas Particleboard - weak material –Small wood particles –No orientation –Uses; Low moisture areas Both products are inferior where strength is required and moisture is present.

Wood Polymer Composite Planks “Artificial Wood” not in wide general use because it is new and untested. Probably will be used extensively in the future because of its stability, durability to weather, and resistance to insects. Advantages: –Decay Resistance –Easy Workability

Wood Fasteners Nails Wood & Lag Screws Bolts Toothed Plates Sheet Metal & Metal Framing Devices Machine Driven Staples & Nails Adhesives

16d Galvanized 16d Sinker Deformed Shank 10d Galv. Spiral Finish Nail Roofing Nail (far right)

Standard Sizes of Common Nails

Machine Driven Nails & Staples Nail Guns, Staple guns –Pneumatic (compressed air) –Electric AC power –Battery operated Pre-packaged fasteners –Collated nail packs –Staples Battery Powered Electric Nailer Collated Nails

Wood Screws Head type Sizing - –Gauge & Length Installation Holding power Uses Drywall screws Deck Screws Types of ‘Heads’

Lag Screws –Large screws –Square or octagonal head –Installed with wrench

Bolts Heavier structural connections Types –Machine –Carriage Washers

Toothed Plates Sheet metal plate punched to form numerous teeth Used with roof & floor trusses Machine pressed into members

Sheet Metal Framing Anchors Used mostly in light Wood Framing as –Joist Hangers –Framing anchors –Angle anchors –Rafter anchor Limited Use with Heavy Timber or Laminated Framing

Adhesives Widely used in the manufacture of wood products –Wood panels –Laminated wood –Cabinetry On Site Uses –Sheathing –Floor decking