Hello,
My contract for replacing decking called for "#1 pressure-treated yellow pine," but the boards I received are stamped "#2 Prime." Aside from the discrepancy with expectations, what's the difference in material properties (and cost) between these two grades of lumber? I've searched the forums and How-To articles for an hour without finding any mention of these designations.
Thanks for any insights.

 

I'd use the #1 for decking where the boards are going to be seen. #2 is fine for joists. If the #2 is for deck boards look at them. Talk your contractor and ask him why you didn't get the #1s? If they aren't "pretty" enough return them. Your contractor might be trying to save you money.

I believe that #2 prime might have more knots, checks, splits, ... than #1. That's the way grading is with other lumber so I assume it would be the same for PT.

The difference in price is may/may not be worth the cost to get #2. I buy "rustic" / common walnut at half the price of "clear". When I look at both grades the clear walnut isn't worth the extra cost difference to me. If you can go to the yard and look at the difference in person, or call them and ask what the difference is.

 

If you search for "treated lumber grades" numerous websites come up that describe the lumber grading system. Here are a couple:

https://www.prowoodlumber.com/en/Pro.../lumber-grades
https://www.decks.com/how-to/168/pressure-treated-wood

 

Thanks tsnider, your perspective helps. The wood was installed before I saw the stamp, and the contractor said that # 1 grade is only good on one side (but my deck is only 4 feet above ground, so underside appearance doesn't matter), and that the lumber supplier only stocked #2 Prime. He agreed he should have informed me of the switch, and has offered to do the subsequent staining/waterproofing at no charge.

 

Pilot Dane,
Thanks, the ProWood link was particularly helpful in understanding the grading terms #1 Grade, #2 Grade, and Prime Grade, including my #2 Prime that was installed before I saw the stamp. From that link:

• "Prime grade lumber provides the same structural properties as #1 grade lumber, but has fewer knots and better appearance
• #2 Prime grade has the strength of #2 grade lumber, but will look better, with fewer knots"

My #2 Prime still seems to have a lot of large knots, but I'm less concerned with it's structural integrity. The contractor has offered to stain & waterproof at no charge to make up for the switch.
Thanks again!

 

PT lumber needs to dry out before staining--maybe 6 months or more. Make sure your contractor will still be around to fulfill his offer and do it right.

 

I've always used the 6 weeks to 6 month rule for staining new PT wood. It depends on how wet the wood was when installed and the environment it's exposed to. Sun and wind will dry the wood out quicker than a shady or damp location.