Prairie Ridge Ecostation

Parallel Strand Lumber

Why is it important to preserve old-growth forests?

Forests can take 150 years to reach late stages of succession, with some forests taking as long as 500 years to become “old-growth.” It takes centuries to millennia for these forests to regenerate, so clearcutting this timber has a lasting impact on the ecosystems they create. The tremendous age of the trees shows that past disturbance events were moderate and did not kill all vegetation. In other words, the forests are fairly stable, allowing many rare species of plants and animals to occupy them over a long period of time.

In addition to influencing the biodiversity of the area, old-growth forests store large amounts of carbon, both above and below ground. This is particularly important because it reduces the carbon dioxide in the air, thereby preventing further warming of the planet from occurring. Not using this kind of lumber therefore may offset the release of carbon dioxide.

How is Parallel Strand Lumber (PSL) made and how is it typically used?

Long strands of wood are laid in parallel formation and are bonded together with an adhesive. PSL is used for beams and headers that require high bending strength and it is sometimes used for columns.

Parallam beams in the Outdoor Classroom.

Is it easy to acquire Parallel Strand Lumber for home construction purposes?

Absolutely. It is now much easier to find PSL in lumber stockyards and its price is reasonable.

Are there any other benefits of using Parallam (also known as PSL)?

PSL offers superior strength because defects are removed from the wood during the manufacturing process. The wood is also produced at the moisture content of most wood in service conditions, making it less prone to shrinking, warping, bowing, cupping and splitting.

Parallam also provides greater flexibility in design because extremely long beams, which would ordinarily require an old, mature tree, can be made to order. In our outdoor classroom, one beam spans the entire length of the building. Parallam also requires no special tools, making it as easy to use as any other lumber.