Selecting Lumber

Interest Approach Look at the piece of wood you are given. Write down as many observations as possible. Measure the dimensions of the piece of wood. Write them down with your observations.

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?

How are lumber and other wood products produced and processed? Problem: How are lumber and other wood products produced and processed?

Lumber Production and Processing trees are cut down transported to the sawmill logs are soaked until sawing time prevents checking, cracking, and warping bark is removed plain-sawed or quarter-sawed

Plain-Sawing Cutting the log on a tangent to the growth rings faster less waste lower cost lumber used in buildings

Quarter-Sawed Lumber Cutting the log perpendicular to the growth rings less likely to warp, shrink, and swell used to make furniture

Drying Lumber Green lumber Seasoning Freshly cut lumber with 20 percent or more moisture. Seasoning Process of drying lumber to the point where it is ready to use.

Drying Lumber Air drying Kiln-dried Set outside to dry Takes 1-3 months Moisture content to 15% Kiln-dried uses a large oven or kiln to dry Moisture content to 6% to 12%

After Drying Run through a planer to make it smooth and dimensional

Plywood: a series of layers (3, 5, or 7) glued together with the grains arranged at right angles to each other to form a 4×8 sheet strength is maximized

Particle Board 4×8 sheet made by gluing wood chips, splinter, and sawdust together used under countertops and in some furniture cheaper warps quickly when it gets wet

Waferboard (OSB or Chip board) gluing wood chips to form 4×8 sheets cheaper more water resistant Used in roof sheathing and subflooring

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

Veneer Thin layer of material that is glued to an inferior quality material. low cost furniture is often particle board with a veneer wood grain surface layer

How is lumber graded and selected for use? Problem: How is lumber graded and selected for use?

Lumber Grading and Selection Wood for lumber is divided into two broad categories, “softwood” and “hardwood”. Refers to the type of tree they come from

Hardwood lumber cut from broad-leaved (deciduous) trees that drop their leaves in the fall Oak, maple, cherry Fine furniture

Softwood Lumber cut from coniferous (cone-bearing) evergreen trees with needle-like leaves construction lumber

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

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

Matching Lumber to job Use the lowest quality of lumber suitable for the purpose. Requires a knowledge of the characteristics of each species of wood.

Properties of Wood Good understanding of wood properties is essential for intelligent lumber selection. Properties Include: Hardness Bending strength Stiffness Compression strength Toughness

How is lumber sized, purchased, and stored? Problem: How is lumber sized, purchased, and stored?

Worked lumber Wood that has been Shaped (trim) Matched (tongue-and-groove) Patterned (molding)

Actual vs. Nominal Dimensions The difference between nominal and actual (dressed) dimensions of lumber is the result of: Planing, Shrinkage that occurs during drying.

Actual vs. Nominal Dimensions Nominal dimensions (2×4, 1×6, etc.) are used when ordering lumber Project planner uses the actual planed dimensions (¾×3½ , 1½×7¼, etc.) to determine the number and length of boards needed

Actual vs. Nominal Dimensions Softwood nominal widths are 2, 3, 4, 6, 8, 10, and 12 inch. Standard available lengths are even feet from 6 to 20.

Actual vs. Nominal Dimensions To find the actual width for nominal widths of 6 inches or less drop ½ inch. For nominal widths of over 6 inches drop ¾ inch to find the actual width.

Linear feet length in feet without regard to thickness or width Thickness of these sheets vary through a range of ¼, 3/8, ½, 5/8, to ¾ inch Generally sold by the 4×8 sheet Plywood, Particle board, Paneling are generally sold by the 4×8 sheet.

Actual vs. Nominal Dimensions All of these materials are priced either by the square foot or by the sheet. Other building materials, such as roofing and siding, are sold by “the square”. “The square” actually means 100 square feet of surface coverage.

Ordering Lumber Do not order large quantities of lumber long in advance When storing lumber, care should be taken to avoid: Warping, Staining, and Moisture absorption problems.

(Picture Courtesy, Interstate Publishers, Inc.)