Douglas Fir is Crap.

[Bob Smalser]

Q: You sure it is Doug Fir?
A: Of course I’m sure. I’m a contractor.
Q: OK, I’ll come and look.

Here’s what I found:



S-P-F is Spruce-Pine-Fir, a lumber marketing group of predominately Rocky Mountain and eastward softwoods that includes rot-prone Balsam and Alpine Fir, but not Douglas Fir. The grouping also can include Red, White, Black and Englemann Spruce, and Jack and Lodgepole Pine, all of which are prone to rot.




H. Fir is more commonly found under the abbreviation Hem-Fir, a lumber marketing group of predominately West Coast softwoods that includes Western Hemlock and five of the True Firs: California Red Fir, Grand Fir, Noble Fir, Pacific Silver Fir, and White Fir. All rot easily.

While that “H. Fir” stamp had me fooled too from a distance, here’s what a Douglas Fir grade stamp looks like, friend. Either take your reading glasses with you next time or take a picture for me.

[Mike Archambeau]

Good analysis, but sure wonder why that wood is wet in the first place. If the exterior flashing and siding were keeping the water from the framing material, there would be no rot.

[Bob Borzelleri]

I'm not sure that I understand the point of this post. The title says Doug Fir is crap and then goes on to list all the various woods that some folks call DF but are not. How does that make DF crap?

[Peter Quinn]

My sill isn't stamped, but its black locust, and it doesn't rot easily. Bugs don't like it, and neither do drill bits!

Nice info for those unaware of the differences. Not sure DF is going to be a much better performer when the building is poorly constructed and causes the framing to get and remain wet. They call it drying in a house for a reason, no?

[John Thompson]

I made numerous work-bench bases from old growth DF I recovere in the form of beams from an old civil war warehouse in Atlanta near the rail-yards that were being torn down to build the Georgia World Congress Center. The stuff was hard as nails and as straight as the day it was milled. But... it never got wet inside.

[Bob Smalser]

Good analysis, but sure wonder why that wood is wet in the first place. If the exterior flashing and siding were keeping the water from the framing material, there would be no rot.

I'm not sure that I understand the point of this post. The title says Doug Fir is crap and then goes on to list all the various woods that some folks call DF but are not. How does that make DF crap?

The house dates from 1983 and was built with minimal crawl space with minimal vents, the dirt floor of which flooded every winter.....apparently sufficiently to wet the fiberglass batts stapled to the floor and rim joists. Lack of air flow combined with wet batts drove the wood MC to above the 20% threshold required for rot.

And DF isn't crap. Its heartwood has moderate resistance to rot and in this cold climate fares very well....even in wet conditions. And certainly better than Hemlock. In this case the SPF stock was limited to the rim joists (SPF doesn't even grow here....I'm surprised a lumberyard here even had any.) and my contractor friend misread the H. Fir grade stamp in the crawl space.

This DF deck on a log-and-plank footbridge on one of my timberlands getting 70" of rain annually dates from 1940, and while on its last legs, is still serviceable.

[Myk Rian]

I'm not sure that I understand the point of this post. The title says Doug Fir is crap and then goes on to list all the various woods that some folks call DF but are not. How does that make DF crap?

I was wondering the same thing.

[Dan Friedrichs]

Very interesting, Bob! I always like to read your posts.

[Bob Smalser]

And for those who don't get to read many grade stamps:



This board was milled at the Seattle-Snohomish Lumber Mill, was graded out as Select Structural as certified by the West Coast Lumber Bureau, and is coastal Douglas Fir Kiln Dried to the international Heat Treatment (HT) standard of 56/30 or 56 degrees C for 30 minutes to insure it is pest-free. This standard generally correlates to 19-20% MC for exterior and framing use.

[Tony Shea]

Although I agree with your analysis of the lumber used in the pictures I would have to say that the fact that the lumber used wasn't doug fir is the least of the problems. IMO if the lumber was doug fir than it still would have experienced rot issues but may have been delayed by a small amount. The bridge you show I would assume gets fresh air blowing over it on a daily basis to help dry it out after getting wet. Which is a completely different situation than having water trapped in the framing of a house that is not constantly getting air dried by the wind and sun.

But I do like the post with a focus on identifing lumber types by their stampings. This is often overlooked.

[Bob Smalser]

More Stampology:



A Spruce-Pine-Fir (S-P-F) 2X10 Surfaced-Dry (S-Dry as opposed to Green or S-Green), kilned to 19% and run through a thickness planer....and graded out as No 2 Structural under the supervision of the Cariboo Lumber Manufacturer's Association (CLMA)at whatever client mill is on their books as Mill #15.

A board originating in Canada. Graders are generally mill employees, and mills subscribe to a Grading Bureau like CLMA or WCLB (above) who provide trainers, certify the graders and do unannounced spot checks.

Small sawmilling operations with only an occasional requirement to provide graded lumber contract with the local Grading Bureau for grading service by the day or half day. They generally send the inspector whose mill circuit is closest to your location.

[Aaron Wingert]

As a building inspector I sure wish more contractors understood grade stamps. Too many times I've seen plans require select structural lumber and #2 gets used. Too many times I've seen struc1 sheathing spec'd and $6 OSB gets used. Standard and better lumber isn't as good as #2, etc. The list goes on and on, and my explanations often generate blank stares on the jobsite.