I am rebuilding my deck and have had some contractors state that they would use #2 pressure treated decking lumber instead of #1. What is the difference between these two grades of lumber?

#2 or better is the grade supplied by lumber companies. It meets code and there is no noticable difference for deck applications. Generally #1 "only" is used when specified by a structural engineer. Which is rare, you can get maybe an extra foot or so on a span typically, so if you're out to the limit or building a beam something like that #1 may be asked for.

Alter Eagle Construction & Design

[This message has been edited by Altereagle (edited June 25, 2003).]

Respectfully, I must disagree AlterEagle- (unless you're only speaking to using a #1 vs a #2 on the supporting structure of a deck)

We treat both #1 and #2 Southern Yellow Pine at my plant. Since SYP makes up most of the pressure-treated lumber that's produced in the US, it's a good bet that BrianZ will be using SYP. That said, there is a distinct visual difference between the two, as well as a slight structural difference. There are less wane and knots allowed per SPIB grading rules in a #1 than there is in a #2. That alone is a big difference visually. #1 material is generally slightly stronger than #2, but I don't see any reason to go wild and use #1 material on the joists and ledger board on the deck. Additionally, your posts are generally going to be #2 if they are 6x6's, as #1 is very difficult to come by in SYP timbers.

Decking will be either PREM or STD, Premium being the equivalent of a #1, and STD a #2. I'm not a big fan of using 2x6 as decking. I'd rather go with a 5/4x6 radiused edge decking. And if it was my deck, I'd use premium decking. It's just a lot better than the standard.

I hope this helps Brian...

[This message has been edited by JayF (edited June 29, 2003).]

Good point Jay, I was only refering to structural.

Here on the west coast we wouldn't even think of using a treated lumber as a finish, we use composites, redwood, cedar & some exotics like ipe (pronounced eepay)among many... but never a treated lumber.

Thanks for clearing that up, I recall using treated pine back east but haven't for so many years never thought of that as an application even!