Naturally durable species and exotic hardwoods
There are two kinds of wood – softwoods and hardwoods. Contrary to their names, the “hardness” of the wood species does not define the characteristics:
- Softwood refers to wood from coniferous (with needles) or evergreen tree that grow quickly and can be cut easily. They tend to keep their needles throughout the year. Softwoods are frequently used as building materials. Examples of softwood trees are cedar, Douglas fir, juniper, pine, redwood, spruce and yew.
- Hardwood refers to wood from broad-leaved trees such as oak, ash or beech. These are deciduous trees that shed their leaves during autumn and winter. Hardwoods are more likely to be used in high-quality furniture, decks and flooring. Examples of hardwood trees include beech, hickory, mahogany, maple, oak, teak and walnut.
NATURAL CHARACTERISTICS OF WOOD
Common lumber defects:
- Wood is a natural living material that absorbs moisture. When moisture content in different parts of the wood changes unevenly, and different parts of the wood dries at a different rate, it causes the wood to crack, check and warp.
TYPES OF WOOD WARPING INCLUDE:
- Bow: a warp along the length of the face of the wood
- Crook: (also called wain) a warp along the length of the edge of the wood
- Kink: a localized crook, often due to a knot • cup: a warp across the width of the face, in which the edges are higher or lower than the center of the wood
- Twist or wind: a distortion in which the two ends do not lie on the same plane
- Mature vs Juvenile wood
- Heartwood vs Sapwood
- Sapwood is the living, outermost portion of the tree and is typically lighter in color than heartwood. Sapwood contains a lot of moisture. It will shrink when dried and is more susceptible to termites, bugs and fungus. Untreated sapwood of virtually all species has very little decay resistance.
- Heartwood is the dormant, inner and darker section of the wood. It is far less susceptible to decay and fungus and has much less moisture than sapwood which means less shrinkage when dried. The heartwood of some wood species is naturally termite-resistant.
Grades of Lumber
Wood is graded based on the number of defects in the board. These are either natural to the lumber of occur as a result of the drying process.
HARDWOOD GRADES (NON-STRUCTURAL LUMBER):
|Grade Name||Min Board Size||Usable Material||Uses|
|First and Seconds (FAS)||6″ x 8′||83.3%||Best and most expensive grade, suitable for fine furniture and cabinetry|
|Select (Sel)||4″ x 6′||83.3%||Cost effective substitute for FAS when only one good face is required|
|#1 Common (#1 Com)||3″ x 4′||66.7%||Good value if small pieces can be used|
|#2 Common (#2 Com)||3″ x 4′||50.0%||Suitable for paneling and flooring applications|
|#3 Common (#3 Com)||3″ x 4′||25.0%||Economical, suitable for crates, palettes and fencing|
Softwood Grades (Appearance vs structural strength):
|Grade Name||Description / Uses|
|A Select||No knots or visible defects. Suitable for fine furniture and cabinetry|
|B Select||Near perfect with few small defects. Used for furniture and flooring|
|C Select||Small tight knots, may be near perfect on one side. Suitable for cabinets|
|D Select||Small knots and blemishes may be visible. Suitable for some furniture|
|No. 1 (construction)||Tight and small (dime-sized) knots. Suitable for shelving and paneling|
|No. 2 (Standard)||Tight but larger knots. Suitable for general woodworking projects|
|No. 3 (Utility)||Large knots. Suitable for fencing, boxes and crates|
Softwood lumber usually comes with a stamp that provides information on grading agency/association, sawmill/manufacturer, grade, species and moisture content.