How to Build With Douglas Fir Beams

Select the highest grade Douglas fir beam affordable for the design application. "Select Structural" and "Number 1 and Better," with 50% and 20% higher ratings than construction grade, respectively, are the premier grades that should be selected when heavy load-bearing strength is required. Ensure that imported timber comes with a Verification of Legal Ownership (or VLO) certificate.

Design applications with both strength and beauty in mind when working with Douglas fir. Many people focus specifically on the structural integrity of this wood but ignore the fact that Douglas fir is also a beautiful color and takes all forms of stain and paint. Use pressure-treated Douglas fir for all exposed-to-weather load-bearing designs where future access is limited -- such as bridge abutments. Unlike other softwoods, such as pine and hemlock, Douglas fir can be used "green", holding its shape without any drying, as it dries after erection or application.

Cut Douglas fir with the highest power saws available. Unlike lesser grained woods, Douglas fir will not split when cross-cut or ripped with a heavy-bite saw blade. Douglas fir can be cut at any angle without losing its structural integrity.

Carve Douglas fir with any vertical plunge-cutter or router. While some cleanup is necessary with chisel and hammer, this can be done rapidly without any risk of damaging the joint or mortise. Unlike with pine or redwood, Douglas fir allows for combination-cuts with partial-saw and partial-router carvings. Curved and cross-grain carvings are also possible without reducing the tensile strength of the timber, as Douglas fir has an extremely high elasticity.

Another characteristic contractors who use Douglas fir enjoy is the ability to drill this wood with extra long augers. It can be drilled at any angle with augers up to 48 inches in length. Counter-boring is also no problem with Douglas fir and comes in handy when building multi-part timbers on site.

Join multiple Douglas fir beams and timbers on site without compensation for shrinkage or settling. Drill the counter-sink hole first and then the penetration bore. Drive up to 1-inch diameter carriage bolts through double washers, wrench-pound them tight and spot-weld the nuts to the bolts.

Distress Douglas fir with hatchets, knives, pull-knives, gouges and adzes. Use a felling axe to cut off edges and distress the surfaces to the desired degree of rough-hewn character. Apply weak bleach to remove natural color and add an aged look as it weathers.