A Greener Construction Sector due to Diameter Breast Height
Diameter Breast Height (DBH) is a timber-industry gauging factor used to determine the economic feasibility of felling a tree for lumber. It’s a simple measurement with the diameter of the usable trunk material (no bark) taken ~ 4-1/2’ from the ground (Breast Height). An 18-22” DBH was once considered the economically viable measurement for Spruce Pine Fir (SPF) strands providing larger dimensional lumber. These tree sizes were readily available in old growth forests. Timber terms and data loosely collected from both:
John Mack’s Economics of Forest Resources
To open a construction component design blog with forestry and timber terms may seem a little odd. This is a blog on positive outcomes with lumber and construction intelligently adapting to the loss of old growth and scarcity of larger dimensional products (2×8, 2×10 & 2×12).
This boon of compatible technology development is obviously economically driven. ~50-years growth cycles, under ideal growing conditions, are now required for commercial timber strands to reach the DBH requirements for larger dimensional products. This is easily extended well passed 70-years or more due to likely variables of a complex environment (severe weather, drought, pests and fire).
Comparatively, SPF timber can attain a 10″ DBH and profitably harvested as 2x4s at ~23 years of age (Frank Roth, Thinning to Improve Pine Timber). Additional attributes of spruce pine and fir softwood strands are their typical yield of tall straight trunks with few knots or other blemishes. Properly managed strands bring a much greater Return On Investment (ROI) to the timber companies and are sustainable resources for the planet at large.
“For every ton of wood grown, a young forest produces 1.07 tons of oxygen and absorbs 1.47 ton of carbon dioxide.” Diaphragms and Shear Walls (American Plywood Association).
For 2×4 construction, to less waste on site, less energy during construction and better insulation, some analysts place softwood component construction as the greenest construction sector by 35% over everyone else. Take a deep breath, get a cup of ice water and kick back with some sunscreen applied on your days off!
Mike Sharkey – Design Professional
Gould Design, Inc.