Chapter 3 Wood

1. Chapter 3 Wood

2. Qualities of Wood • THE MATERIAL WOOD IS: • Strong • Light • Easily handled, worked, & shaped • Fastened quickly & economically • Recyclable • Biodegradable • A renewable resource

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

4. Tree Composition • Bark • Cambium • Sapwood • Heartwood • Pith

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

6. 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.

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

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

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

10. 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

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

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

14. 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.

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

16. 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.

17. 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”

18. 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.

19. 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.

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

21. Wood Panel Products • Why Panelize? • More “controlled” product • Efficient use of forest products • Increase labor productivity • Types • Plywood panels • Composite panels • Non veneered panels

22. 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 because of increase in labor cost.

23. Non-veneered Panels • Oriented Strand Board (OSB) • Waferboard • Particleboard • Fiberboard Fiberboard Particleboard

24. 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

25. Plywood Compared To OSB According to the “Georgia Pacific Corporation” the largest producer of panel products: • 1994-1995 • Plywood Production was 19 billion square feet and declining • OSB Production was 10 billion square feet and increasing • 1999 - 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.

26. 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.

27. 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

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

29. 16d Galvanized 16d Sinker Deformed Shank 10d Galv. Spiral Finish Nail Roofing Nail (far right)

30. Standard Sizes of Common Nails

31. 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

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

33. Lag Screws • Lag Screws • Large screws • Square or octagonal head • Installed with wrench

34. Bolts • Heavier structural connections • Types • Machine • Carriage • Washers

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

36. 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

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