UNIT 1
Wood and Lumber
Unit Objectives
Students should be able to:
Name the parts of a tree trunk and state their functions.
Describe methods of cutting the log into lumber.
Define hardwood and softwood, give examples of some common kinds, and list their characteristics.
Explain moisture content at various stages of seasoning, tell how wood shrinks, and describe some
common lumber defects.
State the grades and sizes of lumber and compute board measure.
CHAPTER 1 Wood
Please refer to the PowerPoint Presentation for this chapter.
Chapter Outline
A. Structure and Growth
1. Wood comes from trees made up of different kinds of cells.
2. Tree growth takes place in the cambium layer.
3. Counting annular rings reveals a tree’s age.
B. Hardwoods and Softwoods
1. Hardwood comes from deciduous trees.
2. Common hardwoods include ash, birch, cherry, hickory, maple, mahogany, oak, and walnut.
3. Softwood comes from coniferous trees.
4. Common softwoods include pine, fir, hemlock, spruce, cedar, cypress, and redwood.
C. Wood Identification
1. The best way to learn how to identify different wood types is by working with them.
2. Study the grain, weight, and smell of the wood.
Any wood products or cross-sections that you can show the students will help them gain a better
, understanding of the material.
Summary
Understanding the parts of a tree is important. Carpenters are called upon to construct a wide variety of
wood structures, floors, cabinets, and other interior sections of houses and buildings. Knowing which
type of wood should be used for various tasks helps ensure quality work. Practice and experience will
lead to the ability to identify wood types.
Key Terms
Annular rings—The rings seen when viewing a cross-section of a tree trunk; each ring constitutes one
year of tree growth.
Cambium layer—A layer just inside the bark of a tree where new cells are formed.
Close-grained—Wood in which the pores are small and closely spaced.
Coniferous—Cone-bearing tree; also known as evergreen tree.
Deciduous—Trees that shed leaves each year.
Grain—In wood, the design on the surfaces cause by the contrast, spacing, and direction of the annular
rings.
Hardwoods—The wood of broad-leaved dicotyledonous trees (as distinguished from the wood of
conifers).
Heartwood—The wood in the inner part of a tree, usually darker and containing inactive cells.
Lignin—The natural glue in wood that holds together the wood cells and fibers.
Medullary ray—Bands of cells radiating from the cambium layer to the pith of a tree to transport
nourishment toward the center.
Open-grained—A texture quality of wood where wood cells or pores are open to the surface.
Pith—The small, soft core at the center of a tree.
Sapwood—The outer part of a tree just beneath the bark containing active cells.
Softwood—Wood from coniferous (cone-bearing) trees.
CHAPTER 2 Lumber
Please refer to the PowerPoint Presentation for this chapter.
Chapter Outline
A. Manufacture of Lumber
1. Bark is removed from logs.
2. Log is sliced into planks.
, 3. Planks are sliced, edged, and trimmed.
4. Lumber is dried.
Any samples of the various cuts will aid in understanding. Allow students to handle the samples
and become familiar with them.
B. Plain-Sawed Lumber
1. Common way of cutting lumber.
2. Produces a distinctive grain pattern on the surface.
3. Least expensive way of cutting.
4. Produces greater widths.
5. Shrinks more during drying and warps easily.
6. Also called slash-sawed lumber.
C. Quarter-Sawed Lumber
1. Produces pieces in which annular rings are at right angles to the wide surface.
2. Less tendency to warp, shrinks less, and dries more evenly.
3. Frequently used for flooring.
4. Also called vertical-grain or edge-grain.
D. Combination Sawing
1. Use of both plain-sawing and quarter-sawing.
2. The sawyer determines the best cut.
E. Moisture Content and Shrinkage
1. Green lumber contains a lot of water.
2. Green lumber should not be used in construction.
3. Using green lumber can result in many construction defects due to shrinking and warping.
F. Moisture Content
1. Abbreviated MC; expressed as a percentage.
2. Indicates water content in wood.
3. Determined by the difference in the weight of the wood before and after it has been oven-dried,
and dividing that number by the dry weight.
4. Wood has reached the fiber-saturation point when all of the free water in the cells has been
removed.
5. Wood shrinks and warps as it dries.
6. Equilibrium moisture content is reached when the MC reaches that of the surrounding air.
, Emphasize the safety reasons for keeping lumber stacked or stored in an orderly manner.
G. Drying Lumber
1. Wood stacked in piles with spacers is air-dried.
2. Wood stacked and dried in large ovens is kiln-dried.
3. Kiln-drying is more expensive than air-drying.
4. Recommended MC for exterior finish lumber is 12 percent, except in very dry climates.
5. Lower MC is used for interior trim and cabinets.
6. A moisture meter is used to determine MC.
7. Most construction lumber is surfaced on four sides.
Have a moisture meter on hand. Using three or four pieces of lumber, show students how to
use the meter.
If available, various warp types should be shown to students.
H. Lumber Storage
1. Lumber should be delivered so that the materials are available in the order of use.
2. Lumber should be protected at the job site.
3. Lumber should be kept in good order.
Having lumber that has been stamped, for the class to see, would help students know what to
look for.
I. Lumber Defects
1. Warps are classified as crooks, bows, cups, and twists.
2. Checks are caused by drying the ends faster than the rest of the stock.
3. Cracks running parallel to and between the annular rings are called shakes.
4. Juvenile wood contains the first seven to fifteen growth rings.
5. Knots are cross-sections of branches in the trunk.
6. Pitch pockets are small cavities that hold pitch.
7. A wane is bark on the edge of lumber.
8. Pecky wood has small grooves or channels running with the grain.
Wood and Lumber
Unit Objectives
Students should be able to:
Name the parts of a tree trunk and state their functions.
Describe methods of cutting the log into lumber.
Define hardwood and softwood, give examples of some common kinds, and list their characteristics.
Explain moisture content at various stages of seasoning, tell how wood shrinks, and describe some
common lumber defects.
State the grades and sizes of lumber and compute board measure.
CHAPTER 1 Wood
Please refer to the PowerPoint Presentation for this chapter.
Chapter Outline
A. Structure and Growth
1. Wood comes from trees made up of different kinds of cells.
2. Tree growth takes place in the cambium layer.
3. Counting annular rings reveals a tree’s age.
B. Hardwoods and Softwoods
1. Hardwood comes from deciduous trees.
2. Common hardwoods include ash, birch, cherry, hickory, maple, mahogany, oak, and walnut.
3. Softwood comes from coniferous trees.
4. Common softwoods include pine, fir, hemlock, spruce, cedar, cypress, and redwood.
C. Wood Identification
1. The best way to learn how to identify different wood types is by working with them.
2. Study the grain, weight, and smell of the wood.
Any wood products or cross-sections that you can show the students will help them gain a better
, understanding of the material.
Summary
Understanding the parts of a tree is important. Carpenters are called upon to construct a wide variety of
wood structures, floors, cabinets, and other interior sections of houses and buildings. Knowing which
type of wood should be used for various tasks helps ensure quality work. Practice and experience will
lead to the ability to identify wood types.
Key Terms
Annular rings—The rings seen when viewing a cross-section of a tree trunk; each ring constitutes one
year of tree growth.
Cambium layer—A layer just inside the bark of a tree where new cells are formed.
Close-grained—Wood in which the pores are small and closely spaced.
Coniferous—Cone-bearing tree; also known as evergreen tree.
Deciduous—Trees that shed leaves each year.
Grain—In wood, the design on the surfaces cause by the contrast, spacing, and direction of the annular
rings.
Hardwoods—The wood of broad-leaved dicotyledonous trees (as distinguished from the wood of
conifers).
Heartwood—The wood in the inner part of a tree, usually darker and containing inactive cells.
Lignin—The natural glue in wood that holds together the wood cells and fibers.
Medullary ray—Bands of cells radiating from the cambium layer to the pith of a tree to transport
nourishment toward the center.
Open-grained—A texture quality of wood where wood cells or pores are open to the surface.
Pith—The small, soft core at the center of a tree.
Sapwood—The outer part of a tree just beneath the bark containing active cells.
Softwood—Wood from coniferous (cone-bearing) trees.
CHAPTER 2 Lumber
Please refer to the PowerPoint Presentation for this chapter.
Chapter Outline
A. Manufacture of Lumber
1. Bark is removed from logs.
2. Log is sliced into planks.
, 3. Planks are sliced, edged, and trimmed.
4. Lumber is dried.
Any samples of the various cuts will aid in understanding. Allow students to handle the samples
and become familiar with them.
B. Plain-Sawed Lumber
1. Common way of cutting lumber.
2. Produces a distinctive grain pattern on the surface.
3. Least expensive way of cutting.
4. Produces greater widths.
5. Shrinks more during drying and warps easily.
6. Also called slash-sawed lumber.
C. Quarter-Sawed Lumber
1. Produces pieces in which annular rings are at right angles to the wide surface.
2. Less tendency to warp, shrinks less, and dries more evenly.
3. Frequently used for flooring.
4. Also called vertical-grain or edge-grain.
D. Combination Sawing
1. Use of both plain-sawing and quarter-sawing.
2. The sawyer determines the best cut.
E. Moisture Content and Shrinkage
1. Green lumber contains a lot of water.
2. Green lumber should not be used in construction.
3. Using green lumber can result in many construction defects due to shrinking and warping.
F. Moisture Content
1. Abbreviated MC; expressed as a percentage.
2. Indicates water content in wood.
3. Determined by the difference in the weight of the wood before and after it has been oven-dried,
and dividing that number by the dry weight.
4. Wood has reached the fiber-saturation point when all of the free water in the cells has been
removed.
5. Wood shrinks and warps as it dries.
6. Equilibrium moisture content is reached when the MC reaches that of the surrounding air.
, Emphasize the safety reasons for keeping lumber stacked or stored in an orderly manner.
G. Drying Lumber
1. Wood stacked in piles with spacers is air-dried.
2. Wood stacked and dried in large ovens is kiln-dried.
3. Kiln-drying is more expensive than air-drying.
4. Recommended MC for exterior finish lumber is 12 percent, except in very dry climates.
5. Lower MC is used for interior trim and cabinets.
6. A moisture meter is used to determine MC.
7. Most construction lumber is surfaced on four sides.
Have a moisture meter on hand. Using three or four pieces of lumber, show students how to
use the meter.
If available, various warp types should be shown to students.
H. Lumber Storage
1. Lumber should be delivered so that the materials are available in the order of use.
2. Lumber should be protected at the job site.
3. Lumber should be kept in good order.
Having lumber that has been stamped, for the class to see, would help students know what to
look for.
I. Lumber Defects
1. Warps are classified as crooks, bows, cups, and twists.
2. Checks are caused by drying the ends faster than the rest of the stock.
3. Cracks running parallel to and between the annular rings are called shakes.
4. Juvenile wood contains the first seven to fifteen growth rings.
5. Knots are cross-sections of branches in the trunk.
6. Pitch pockets are small cavities that hold pitch.
7. A wane is bark on the edge of lumber.
8. Pecky wood has small grooves or channels running with the grain.
