Soft and Hard
Most timber in the United States can be separated into two categories: softwood and hardwood. Softwood primarily comes from conifers that bear cones and needles and do not lose their foliage in winter. Hardwood comes from trees with broad leaves that shed in the fall. Differences between the two types of timber are characterized by density, anatomy and application. Softwood is lighter and softer than hardwood. It has a broader grain pattern with more air space between pores. Hardwood is heavier, more dense, has a tighter grain pattern and is typically stronger than softwood. The two types of timber have specific uses that differentiate them in the building industry. Softwood such as pine and fir are typically used structurally for framing and exterior use. Common hardwoods such as oak, ash and birch are typically used for cabinets, trim and furniture.
Exotic timber is more exclusive than timber used in the building industry. This type of timber is imported. It ranges from soft to hard depending on density, but the majority of exotic lumber is considered hardwood. The variety of exotic timber ranges from high-density iron wood, teak and ipe used in decking and flooring, to low-density timber such as balsa and radiata pine, which is a farmed, imported softwood used for trim and specialty items such as models and crafts. The variety of exotic timber is unparalleled in color, density, grain patterns and character. Ranging from dark red to purple and white to black, exotic timber is prized by furniture and cabinet makers, interior decorators and trim carpenters. Luthiers use exotic timber for stringed, musical instruments. Expect to pay more for exotic timber, but the differentiating grain patterns and color make it a valued addition to a custom project.
Wood products that might be overlooked as a timber product include manufactured beams, studs, planks and sheets. These wood products -- although made mostly from softwood -- often are stronger than hardwood. The strength is a result of overlapping grain patterns. Glulam, or glue-laminated timber, is a wood product created by laminating planks together with grain patterns at 90 degrees to one another. Beams and other framing members manufactured using this process can bear more weight than their solid-wood counterparts of similar size. I-beams are structural members consisting of a combination of laminated panels and glulam lumber and are used for long spans on floor and roof frames. Laminated veneer lumber is thin layers peeled from timber and glued together to create a solid, dense building material used for cabinets, flooring, roofing and structural purposes.
Characterized by a an olive-green or dull brown color and puncture marks along its surface, pressure-treated lumber is used as a weather-resistant, outdoor building material. Pressure-treated lumber is typically created by immersing softwoods such as pine or fir in a chemical bath to give them resistance to decay, insects and rot. The type of treatment and amount of time the wood spends in the bath relates directly to its approved application. For example: pressure-treated timber specified as above-ground should be used only for decking, fencing or other projects that don't touch the ground. Pressure-treated lumber rated for ground contact or direct burial can come into contact with the ground or be buried underground. Ratings for the application of pressure-treated timber are typically stamped on the product.