Douglas Fir (DF) has long been the industry standard for framing materials, the one that all others are measured against. Its superior strength to weight ratio gives it a leadership position in all framing applications. It is the standard for dimensional stability. It has a moderate decay resistance and when properly applied can stand the test of time. Its close grain and tight knot patterns when finished, add beauty to any structure.
From a framing aspect, Douglas Fir is superior to yellow pine and hemlock in almost every application. However, the pine or hemlock is often selected for purely economic reasons. Use of either should be dictated by the type of construction, aesthetics, quality requirements, load specifications and overall expected durability. All have similar workability; however, the Douglas Fir is often preferred because of its close grain and less likelihood of splitting or cracking during the cutting or fabrication.
Oddly enough the Douglas Fir tree is not fir, pine or spruce; but are a unique species. It is the second largest tree in North America and some have reached an over15 feet in diameter and over 450 feet in height while living 500+ years. It is second only to the giant Redwoods, also from the Pacific Northwest.