1. Lumber Grading

2. Objectives
To understand the different ways of grading lumber

3. 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.

4. Lumber Grading and Selection
Softwood: Evergreens (mainly)
Used mostly in construction
Hardwood
Deciduous trees
Furniture

5. Softwood Grading Softwood grading is based on:
Appearance,
Strength, or
Combination of the two.
Defects which can affect both appearance and strength include:
knots,
checks,
splits,
decay,
stains,
insect holes

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

7. Structural lumber
Two inches or more in rough lumber thickness and width
Stress tested and used as:
Joists,
Posts,
Beams

8. Factory or shop lumber Yard Lumber Doors, Window sashes,
Foundry patterns, and
General cut-up purposes.
Yard Lumber
Lumber less than five inches thick
Ordinary construction and general building purposes.

9. Yard Lumber
While blueprints may specify stress rated structural lumber, most building is done with yard lumber.
Yard lumber includes select or finish boards, common boards, and dimension lumber.

10. Select or finish boards
Typically one inch thick (1 × 4,1 ×6,etc.)
Used as an inside surface to be coated with varnish or paint.
Common Boards:
One inch thick,
2 to 12 inches wide

11. 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.

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

14. Plywood Grade is based on the outer plies.
based on the presence of knots, knot holes, and surface plugs.

15. Selecting Grade to Buy
Use the lowest quality of lumber suitable for the purpose.
Inexperienced buyers should depend on the advice of an experienced, reliable lumber yard employee to make grade purchase decisions.

16. Matching Lumber to job
Requires a knowledge of the characteristics of each species of wood.
What to look for when:
Siding for a house:
Good nailing and weather resistant qualities.
House framing members:
Strength and stiffness.

17. Matching Lumber to job Furniture construction:
Attractive appearance, freedom from blemishes and flaws, desirable wood grain, hardness, and resistance to warping are important.

18. Matching Lumber to job
White woods (white pine, fur, and spruce) and yellow pine: Most popular species used in construction.

20. Sizing and Storing Lumber

21. Sizing, Purchasing, and Storing Lumber
May be purchased green air dried, or kiln dried.
They may be rough, dressed, or worked lumber.
Rough lumber: Lumber as it comes from the saw.
Most lumber is planed before it is sold.
Planed lumber is also called: Surfaced, Dressed, and Milled.

22. Board Sizes
Common boards and dimension lumber is bought and sold by the board foot or per thousand feet.
Board feet = thickness × width × length divided by 12.
Molding and trim boards are sold by the linear feet or running feet, rather than board feet.

23. Board Sizes
Linear feet: is simply length in feet without thickness or width.
Generally sold by the 4×8 sheet:
Plywood ect.
Thickness of these sheets vary through a range of ¼, 3 / 8 ,½,5 / 8 , to ¾ inch

26. Ordering Lumber Don’t order long in advance of project.
If delivered lumber must be stored for a period of time, care should be taken to avoid:
Warping,
Staining, and
Moisture absorption problems.

27. Ordering Lumber
Lumber should be neatly stacked using stickers or spacers every few rows to allow air circulation.
If stored outside:
Keep the stack relatively level,
off the ground, and
covered with moisture-resistant covering like plastic.

28. (Picture Courtesy, Interstate Publishers, Inc.)