Which wood is treated?

[mm]

I've been assuming that if some wood from my old deck had rotted some and the other wood is has rotted not at all, the rotted wood was not treated. Is that right?

Specifically, the 30 year old deck that I mostly tore down last spring had 2x4's for the floor that warped etc. but never rotted. I'm sure they were treated, right?

But the 2x8's that went horizontally and held up the floor, and the

4x4's which were the posts, have substantial rot, mostly in the center of each piece and on one side, or at one end, with the rest looking pretty good. Can I assume those were treated?

I am burning in my fireplace the tree that fell down , and would like to burn the non-treated lumber too.

[Mark]

If the deck, and all the wood in it was 30 years old, then it was probably all PT. That is about the life expectancy of PT wood that is exposed and not treated in some manner. Last spring I had a 4x4 PT fence post that rotted off at the ground after 25 years. It had cracked allowing water to get in to the less-treated center of the wood and it pretty much rotted from the inside out.

I'd advise against burning any of the wood as the risk of chemicals isn't worth the danger.

[Phisherman]

PT lasts maybe 20 or 30 years. Not all areas weather evenly or treatment is not even, perhaps one area gets more rain or stays wet longer than other areas. Dispose of unwanted PT wood in the trash.

[mm]

Some of this stuff needed repair, due to mild rotting, as much as 15 years ago, but I'll play it safe. Thank you

And Mark, what you said about rotting in the middle because the stuff doesn't get all the way in makes sense. That applies to the 2x8's at least Maybe a little to the 4x4's The major reason I thought those parts weren't treated is that the floor stayed perfect while for years everything else I could see rotted, even the outermost 2x8. And I didnt' really think he would use PT wood for everything. (although in that case, why the floor?)

[DerbyDad03]

I need to replace a deck board or 2 on my 20 YO deck due to rot. I'd bet a substantial sum of cash that all of the deck boards were treated.

One of them had a knot that fell out and the rot is now spreading outward from the hole, which goes along with the whole "water getting into the interior" discussion.

Gotta do that one before winter. It's right your foot lands as you step down onto the stair landing.

[Mark]

mm,

Not really sure what you're saying here. the decking (surface) are PT, but you don't think the superstructure, 2x8s, 4x4's, etc. are? I can't imagine building a deck that way.

My Bro-in-law has a deck that looked new when he bought his house about 5 yrs ago here in OH, and I warned him I didn't think the deck surface was PT, even though it was stained and looked real nice. This summer he ended up replacing the entire thing since it about totally rotted out.