Lesson A3–8:

1. Lesson A3–8: Selecting Lumber

2. Next Generation Science/Common Core Standards Addressed! • CCSS.ELALiteracy.RST.9‐10 Determine the meaning of symbols, key terms, and other domain‐specific words and phrases as they are used in a specific scientific or technical context relevant to grades 9–10 texts and topics..4 • CCSS.ELALiteracy.RST.11‐12.4 Determine the meaning of symbols, key terms, and other domain‐specific words and phrases as they are used in a specific scientific or technical context relevant to grades 11–12 texts and topics. • HSNQ.A.1 Use units as a way to understand problems and to guide the solution of multi‐step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs

3. Bell Work/ Student Learning Objectives • Explain how to produce and process lumber and wood products. • Discuss the grading and selection of lumber. • Explain the process of sizing, buying, and storing lumber.

4. Bending strength Board feet Common boards Compression strength Dimension lumber Dressed lumber Factory or shop lumber Green lumber Hardboard Hardness Hardwood Kiln-dried lumber Linear feet Nominal or rough lumber Paneling Particle board Pegboard Plain sawing Plywood Quarter sawing Terminology

5. Terms • Seasoning • Select or finish boards • Softwood • Stiffness • Structural lumber • Toughness • Veneer • Wafer board • Worked lumber • Yard lumber

6. Interest Approach • Show samples of various sizes of lumber and examples of wood products such as plywood, particle board, and wafer board. • Ask students questions to spark their interest in learning about selecting, grading, buying, and storing lumber.

7. Interest Approach • What happens between cutting down a tree and you buying the wood as lumber? • How is lumber graded and stored? • How can you determine which type of lumber to buy?

8. Lumber Production and Processing • After trees are cut down they are transported to the sawmill. • The logs are soaked until sawing time to prevent checking, cracking, and warping.

9. Lumber Production and Processing • After removing the bark, the wood is cut into standard lengths and widths and is referred to as lumber. • Logs are either regular/plain-sawed or quarter-sawed.

10. Plain-Sawing • Plain sawing: Cutting the log on a tangent to the growth rings • Is faster with less waste resulting in lower cost lumber. • Produces a flat or slash-grained lumber that is used for most buildings.

11. Plain-Sawing

12. Quarter-Sawed Lumber • Quarter sawing: Cutting the log perpendicular to the growth rings • Results in lumber less likely to warp, shrink, and swell. • Since quarter-sawed edge or vertical grained boards have a prettier grain, they are often used to make furniture.

13. Quarter-Sawed Lumber

14. Drying Lumber • After the lumber is cut, it is ready to be dried. • Seasoning: Process of drying lumber to the point where it is ready to use. • Green lumber: Freshly cut lumber with 20 percent or more moisture.

15. Drying Lumber • Lumber can be stacked outside with spacers to allow air flow between layers. • Air drying takes from one to three months and typically reduces moisture content to 15 percent.

16. Drying Lumber • Kiln-dried lumber uses a large oven or kiln to dry the lumber to 6 to 12 percent moisture. • Starting with high steam and low heat the kiln gradually adjusts to low steam and high heat to remove moisture without creating cracks in the lumber.

18. Drying Lumber • After drying, the lumber in some cases is used rough, also referred to as unmilled or unplaned. • Dressed lumber is smoothed and given uniform dimensions by running it through a planer.

20. Dried and Planed Lumber • Can be processed into a variety of wood products such as: • Beveled siding, • Tongue-and-groove flooring, • Trim, • Molding, • Etc..

21. Plywood: • Wood product made of a series of plies or layers (3, 5, or 7) glued together with the grains of adjacent layers arranged at right angles to each other to form a 4×8 sheet. • By gluing layers so that the grain runs in opposite directions the strength is maximized.

23. Particle Board • 4×8 sheet made by gluing wood chips, splinter, and sawdust together. • Because it is hard and brittle, it is used under countertops and in some furniture.

25. Particle Board • While particle board is cheaper than plywood, it needs to be cut with a carbide-tipped blade and warps quickly when it gets wet.

26. Waferboard • Also known as OSB board and chip board • Made by gluing wood chips to form 4×8 sheets. • Since it is cheaper and more water resistant, wafer board is replacing plywood as roof sheathing and subflooring.

28. Hardboard • Made by gluing wood fibers into sheets. • Since it is hard and brittle, it should be cut with a carbide-tipped blade and it does not hold nails well. • May be used as tabletops or shaped in long boards to use as siding.

30. Pegboard • Pegboard: Hardwood with a series of uniformly sized and shaped holes. • Pegboard is useful as a hand tool organizer. • Peg-board hooks of various sizes are available at most hardware stores.

32. Paneling • 1/8 or ¼ inch sheet of wood or hardboard with a wood grain surface. • Cheap paneling may be hardboard with wood grain contact paper on the surface.

34. Veneer • Thin layer of material that is glued to an inferior quality material. • While high quality furniture is generally solid wood, low cost furniture is often particle board with a veneer wood grain surface layer.

36. Anticipated Problem: How is lumber graded and selected for use?

37. Lumber Grading and Selection • Wood for lumber is divided into two broad categories, “softwood” and “hardwood”. • Refers not to the hardness of the wood, but to the type of tree they come from.

38. Lumber Grading and Selection • Softwood: Lumber cut from coniferous (cone-bearing) evergreen trees with needle-like leaves. (Ponderosa Pine) • Hardwood is lumber cut from broad-leaved (deciduous) trees that drop their leaves in the fall. (Oak, Pecan)

39. Lumber Grading and Selection • Fine furniture is typically made from hardwood. • Since construction lumber is generally softwood this unit will focus on softwood grading.

40. Softwood Grading • Softwood grading is based on: • Appearance, • Strength, or • Combination of the two.

41. Softwood Grading • Defects which can affect both appearance and strength include: • knots, • checks, • splits, • decay, • stains, • insect holes

42. Softwood Grading • Softwood grading classifies lumber according to use: • Yard lumber, • Structural lumber, and • Factory or shop lumber.

43. Yard Lumber • Lumber less than five inches thick • Used for ordinary construction and general building purposes.

44. Structural lumber • Two inches or more in nominal thickness and width • Stress tested and used as: • Joists, -Beams, • Stringers, -Posts, • Timbers, -Truss members. • For the most part, it is wider and thicker than dimension lumber.

45. Factory or shop lumber • Used in: • Doors, • Window sashes, • Foundry patterns, and • General cut-up purposes. • Often referred to as molding

46. Select or Finish Boards • While blueprints may specify stress rated structural lumber for some framing components, most building is done with yard lumber. • Yard lumber includes select or finish boards, common boards, and dimension lumber.

47. Select or Finish Boards • Select or finish boards: Graded A through D based on appearance. • Typically one inch thick (1 × 4,1 ×6,etc.) • Used as an inside surface to be coated with varnish or paint.

48. Common Boards: • One inch thick, • 2 to 12 inches wide • Graded on a combination of appearance and strength from number 1 common to number 5 common.

49. Dimension Lumber: • Two to five inches thick • Two inches or more wide • Graded on strength and stiffness. • Dimension lumber grades are: • Construction, • Standard, • Utility, • Economy, and • Economy stud.

50. Graded Lumber • Graded lumber will have a grade mark that includes: • Grade, • Moisture content, • Species of the tree, • Mill where processing was done, and • Certification mark indicating the association that graded the lumber.