Tag Archives: AC2

Properly Pressure Treated Lumber

Trying to Buy Properly Pressure Preservative Treated Lumber

Reader ZACH in BLACK CREEK has been challenged trying to buy properly pressure preservative treated lumber. He writes:

“Hello, I would like to get your opinion on 2×6 grade board. I read the article you wrote about lumber pressure treatment. I have been looking around for .20pcf or higher treated grade board. Called my local lumberyards but can’t get a solid answer besides it meets ground contact spec. Im about ready to give up and buy Menards since they have in stock AC2 .15pcf. I will be pouring an apron in front of building so I wanted a higher treated board. I live near Green Bay, WI but have a trucker in family. What recommendation can you give me? I attached the Menards info also.”

Mike the Pole Barn Guru 

I know Hansen Pole Buildings’ lumber wizardress Justine hears this story from unknowing and/or uneducated lumberyards all over America. At least I hope it is they do not know, rather than they do not care – which would be even worse.

Only pressure preservative treated lumber which is treated to a minimum UC-4B rating is suitable to be buried in the ground. AC2 is Micronized Copper Azole (MCA) and in order to be rated for burial in the ground, it would require a treatment level of 0.31 pcf (pounds per cubic foot) minimum. I really don’t just make this stuff up, here is the proof from the AWPA (American Wood Protection Association): https://www.awpa.com/references/homeowner.asp.

MCA treated to .15 pcf is rated only for contact with the ground, it is not designed for burial in the ground. There is a distinct possibility this product will not give you the lifespan you desire.

My recommendation – stop in at the ProDesk at your local The Home Depot® there in Green Bay (I have been to both of them – good folks at each location) and they can special order what you are looking for. Make sure to specify you want MCA to a minimum of 0.31 and get it in writing on the paperwork when you order. You will have to wait awhile to get it, so be patient.

Also – if this is to be a grade board/splash plank on a post frame building, you truly should be using at least a 2×8, as a 2×6 only gives you 7/8″ of lumber to attach the bottom of your wall steel to given the drip edge of your base trim at four inches above grade.