Classification and Uses

• Trees are classified as hardwoods or softwoods. Softwood lumber is typically used for cabinets, flooring, framing, paneling and millwork. Hardwoods are also often used for flooring and paneling, along with architectural and interior woodwork, according to the Wood Handbook.
  
  

Strength Basics

• All wood has a high ratio of strength to weight, but some wood species are stronger than others. Strength in wood is expressed by both its bending strength and its compressive strength, according to the Wood Handbook. Do not confuse the stiffness of wood with its bending strength, although those are both mechanical properties of wood, according to the University of California at Riverside. When engineers measure the strength of wood, they measure bending strength and compressive strength in pounds per square inch (psi). They test bending strength by loading blocks on top of wood perpendicular to the grain until the wood breaks and they measure compressive strength by loading blocks of wood parallel to the grain until it breaks.
  
  

American Softwoods

• Yellow pine is the strongest of the North American softwoods commonly used in the U.S. It has a compressive strength of 8,470 psi and a bending strength of 14,500 psi. Next strongest is Douglas fir with a compressive strength of 7,230 psi and a bending strength of 12,400 psi, followed by Hemlock at 7,200 psi and 11,300 psi, respectively.
  
  

American Hardwoods

• Hickory is the strongest hardwood with a compressive strength of 9,210 psi and a bending strength of 20,200 psi. Yellow birch is the next strongest with a compressive strength of 8,170 psi and a bending strength of 16,600 psi, followed by hard maple at 7,830 psi and 15,800 psi, respectively.
  
  

Imported Woods

• One imported wood species is stronger than the North American species. Bubinga has a compressive strength of 10,500 psi and a bending strength of 22,600. Bubinga lumber is a dense hardwood from Africa that's also known as African rosewood. Purpleheart is nearly as strong with a compressive strength of 10,320 psi and a bending strength of 19,200 psi, followed by Brazilian rosewood at 9,600 psi and 19,000 psi, respectively.