Beams for 20” wide post and pier foundation

[BigMish]

I’ve got a few questions about the beams for the ports and pier foundation for the 20” wide 1 ½ story cottage:
- What does the “D/F #2” specification of the 2x12s mean? Would Millstead
2 In. x 12 In. x 12 Ft. Pressure Treated Lumber be acceptable for this application?
- What does “offset joints min 4’. Brace to posts mean”?

Thanks, Mischa

[MountainDon]

"D/F #2" = Douglas Fir, grade #2 or better. Look at the lumber grading stamp on each piece.

"offset joints min 4 ft" = In building long beams from multiple layers of shorter sections a joint in one layer must be at least 4 feet from any joint in another layer. See  Built-up Beam

I imagine the PT lumber would be okay if it was Doug-Fir. But you probably don't need to go to the trouble/expense of PT if your beams are high enough off the ground. I think that's 12 inches?? We'll see what John or the others say. Guys?

[John Raabe]

PT (pressure treated lumber) is required when closer than 6" to soil. In my area of the woods PT lumber is usually hemlock and the treatments work best with softer woods. Doug Fir is generally too hard for many treating facilities.

Ask at the lumber yard for the structural rating of their PT lumber. Also, you can always "substitute up" - an old and proven practice... For example, if a high quality structural 2x8 is called out and you have lumber of questionable or unknown pedigree, just go up a notch to 2x10.

[BigMish]

Got it. Thanks guys.

That article, the “Built up beam”, was very helpful. Hadn’t seen that technique in any of my books. Is there a list of articles similar in this website that I haven’t yet found?

[John Raabe]

I'm sure there are nuggets out there you haven't yet found (and probably don't yet know you need to see!  8-))

Always a good idea to use the site search button when exploring a new topic. This site has many years of stuff piled up in the corners.

[BigMish]

Ha! Right you are: just as a test I searched for "beam" and what was the first result? The Builtup Beam article.

Thanks for the tip, that might keep me off you backs with questions for a while!

.M