All of our treated lumber, from 2x4x8 to 2x12x20 is premium or number one grade. Many retailers say they will save you money without telling you they sell lower grades. We know you want quality. You buy treated lumber because you are going to expose it to the worst Mother Nature can dish out. That may be up in the air, or it may be against the ground. All of our treated lumber is MCA treated for ground contact use. All of our treated boards are stored under roof to minimize the exposure to both sun and rain.