Pressure treated ID??

Almost certainly one board is more dried out than the other and weighs more since the treating process.

S-GRN means that the stock was greater than 19% moisture content when surfaced.

NLGA is a Canuckistani grading rules authority.

S-P-F is Spruce-Pine-Fir and can include any of these three as a mixed lot.

S-P-P doesn't mean anything to me.

I would say that you have one piece that has simply lost more moisture than the other.

Tom Watson - WoodDorker tjwatson1ATcomcastDOTnet (email)

Tom Watson wrote: ...

I'm thinking the S-P-P is a S-P-F that got blurred in the stamping, maybe...and concur completely on the density difference being primarily water...

Thanks everyone....The heavier piece even looks different....wow - 4 1/2 pounds more water than the other one !!!! Just one 8' piece was different than the rest....Almost looks like Douglas fir - The green preservative is very dark on this one but it could be because the wood is so wet.

KP

Would be very rare for PT to be Doug fir--it's far too dear to be used up that way by the mills...

I would suspect that if you dry the two pieces for a month or so they'll be very similar in weight. It is quite possible they're different varieties of SYP and one is more open grained than another so there is some inate density difference, but I'd wager pretty heavily it's simply water...

Certainly can be different species. Can also be from crowded wild versus controlled tame plantations, with a lot more cellulose in the one that grew crowded. Rings will be closer together.

Of course, it's also possible, but less so, given the difference in appearance you mentioned, that they're the same and one was on top in the sun, the other protected in the stack.

Tom Watson wrote

I just bought some pressure treated softwood and it 'steamed' when drilled or sawed it was that wet!

Dave