The arsenic (CCA) treated lumber that killed young children even if they just looked at it is still available. You just need to go to a lot of trouble to get your hands on it. The stuff previously found in big box stores was .4 or .6 pcf. The really good stuff is 2.5 pcf. That was never in the big box stores. It’s still available too.
The marine grade, 2.5 pcf, is a very dark green, almost black color. If you’re near a coastal area, it’s easier to find.
My stepfather and I treated lumber with that old arsenic back in the early 80’s. I’m surprised we are both alive.
It was very dark brown at that time.
I always though pressure treated lumber was to repel wood eating critters, not moisture rot. This is an important distinction. Here in VA where I live they like bare lumber on their decks for whatever reason. It is probably pressure treated, but if it is not weather proofed the sun in exterior exposed lumber will make it dry rot and in damp areas will let it mold. Anyone know the distinction?
It does not state in the article IF they even used pressure treated lumber to begin with. ACQ .40 is fine as long as it is not direct ground contact. However, if it was my house, I would use .60 ACQ or CCA. It sounds like they did not use pressure treated at all on the subfloor foundations of the houses. I do not know the LA building codes, but I suspect the contractor is at fault.
My sister, and her husband, in Seattle, bragged about the deck they built, a couple years ago, because it was made of some “sustainable material” stuff, as opposed to ordinary wood. This past summer, they had to tear the deck down, turns out the “material” was highly valued by wasps, who nested there in great numbers, making the deck area dangerous for her young children to play on, or near. The replacement was made of . . . arsenic treated lumber. Hopefully, the kids won’t look at it ;)