Douglas Fir has the highest ratings of any western softwood for fiber stress in bending, tension to parallel to grain, horizontal shear, compression perpendicular and compression parallel to grain. Douglas Fir is often the standard against which all other framing species are measured. Its strength combined witha superior strength-to-weight ratio, high specific gravity, the moderate decay resistance of its heartwood, and documented excellent performance record against strong forces resulting from winds, storms and earthquakes, have given Douglas Fir its reputation. It is also tight knotted and close grained, adding the bonus of beauty to its structural capabilities. Color, grain pattern, knot size and type are addressed in the rules for appearance grades.
Dimension lumber grading rules limit natural characteristics and manufacturing imperfections that affect the strength and utility of the piece
Structural lumber (including dimension lumber) is visually and/or mechanically (MSR) graded for its strength and physical working properties (appearance is secondary, unless specified)
The wood is very stiff and strong for its weight, and is also among the hardest and heaviest softwoods commercially available in North America
Doug-fir is often installed in its "green" or unseasoned state, and allowed to air dry during constructionBrand/grade may vary based on availability and stocking location