I’m building a ground level deck in San Diego and trying to source suitable framing lumber. I understand that ground contact rated pressure treated lumber is required, but I’m under the impression that green PT lumber warps over time. Some forums recommended KDAT (kiln dried after treatment) lumber, but I’ve tried 4 lumber yards in the area and they don’t sell KDAT.

Should I keep trying to find KDAT, and if so, can anyone recommend how? If not, what steps should I take to make sure my deck doesn’t warp or come apart if I use green PT wood?

  • Buy lumber at your local lumber yard (San Diego must be big enough to have more than 4) - remember that big-box home improvement stores have a very limited selection of lumber. Try an actual lumber yard. If you choose not to purchase KD lumber, buy it now, then let it sit for a couple of months. Even in the winter San Diego will be dry enough for the lumber to dry. You'll get some boards warping, so you'll need to buy extra and skip the warped ones. FYI- I built a deck 5 years ago in the humid midwest, didn't wait for it to dry, and haven't had warping except for some of the decking.
    – FreeMan
    Commented Oct 20, 2023 at 17:15
  • Thanks for the tips and resources. @FreeMan, I checked two actual lumber yards and two big box stores. It seems like people are saying green PT wood shouldn’t be a problem if you choose your cuts wisely and let them acclimate correctly, so I think I’ll go for that.
    – ipetrik
    Commented Oct 20, 2023 at 19:11

1 Answer 1


If you buy wet pressure treated wood, then you'll want to let it dry out for a couple of weeks before using it. Buy some 2x2s to lay on the ground as racks to elevate the pressure treated lumber off the ground. Arrange the lumber by standing it up on edge and leaving an inch or two of space between each piece so that air can circulate. Cover it with a tarp so that the sun can't evaporate the water out of one side much faster than the other, as that will result in warping. Leave the ends of the tarp open to air flow.

You can buy lumber moisture meters for under 20 USD on Amazon, where that might be worth the investment. Maybe the copper in the pressure treatment chemicals messes with the readings, though.

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