MATERIALS : Engineered Wood Could, Should Be on Alternatives List
Engineered or manufactured, lumber makes wood a realistic alternative in situations that might previously have called for other materials.
Some of these materials, such as steel, are manufactured from resources that are not renewable.
Also, using structural steel on a project often requires specialized tradespeople and equipment, which can add considerably to the cost of a job.
Because engineered wood uses raw materials of short length and width, trees that would normally be considered weed trees--useless for construction or trim work--can be cut up and used to make engineered lumber. These trees, aspen being the most common, are plentiful and grow quickly.
Using these trees for structural products opens up a new, readily renewable source of raw materials. Natural defects that occur in the wood, which would normally cause a piece of lumber to be rejected for structural use, are either cut out or spread randomly throughout the reassembled beam.
This technique generates a much higher yield of usable material from any given tree.
Another feature of engineered lumber is dimensional stability. In a conventionally framed house, it’s common to experience squeaky floors and drywall or plaster cracks that result from shrinkage of the floor joists.
Engineered joists are manufactured from kiln-dried materials that have been saturated with a resin-based adhesive. This yields a product that is extremely stable and will not change dimension either by picking up or losing moisture.
Engineered lumber can contribute in other ways to better constructed buildings. Anyone who works with wood is familiar with warped, twisted and split lumber.
These solid-lumber problems not only decrease cost-effectiveness but can also compromise the integrity of a structure. And defects have become more prevalent as lumber suppliers have had to turn to faster-growing species to keep up with demand. Since manufactured lumber is dimensionally stable, it resists these problems, providing a more uniform and predictable product.
Engineered beams have opened up new possibilities for architects as well as builders. The ability of wood I-beams to carry greater loads than comparable-size solid-wood joists provides increased flexibility in placing bearing walls and support beams, while maintaining a relatively thin floor structure.
The result can be a more expansive floor plan.
As you might expect, the benefits of these products do not come without cost. Typically, engineered wood items are priced about twice that of a comparable length of solid lumber.
The manufacturers of these products are quick to point out, however, that the combined factors of less waste, greater strength, faster installation and lighter weight per unit length all contribute to savings that offset the higher cost of the product.