Pressure-treated lumber has been a great innovation for the building industry, extending the life of this already renewable resource. But it’s important to know how to work with it in order to keep your warranty intact—and to protect the life of your appearance-grade treated lumber. In the first installment of this series, we walked through the basics of working with appearance-grade treated lumber. In this post, I get a little more specific and share how we used appearance-grade pressure-treated lumber for a deck project. 

Purchasing decisions for appearance-grade treated lumber

The width of a piece of lumber (especially decking) has a lot to do with how much “cupping” you will experience over time. Cupping is the natural warping that occurs across the width of a piece of lumber. For that reason, I always encourage people to consider using a 4” (nominal width) board. This size of board will end up using more fasteners per square foot, but the result should be a much more stable deck surface.  

We loaded up the material for this particular small decking project on a warm Saturday afternoon, pushing it up over the cab and tying it down. Due to other project priorities, the lumber ended up staying on the truck until we began to install it. This delay exposed the boards to some additional direct sun, which is not ideal. However, a scenario like this is not uncommon with projects. You can't always get the materials home and start working right away.  

Evaluating appearance-grade treated boards for placement 

As we discuss in our video that covers the manufacturing process, the raw lumber that gets used to make appearance-grade treated boards is manufactured to be used for framing new homes or remodel projects. The primary goal for the mill is that it meets the grading standards, not necessarily how it looks. 

At Dunn Lumber, our supplier makes an effort to buy a nicer grade of two-by-four and two-by-six kiln-dried Doug fir for their appearance-grade deck boards. They sort through it again, before treating it, in an effort to pull out boards with visual defects that will impact the intended use. That being said, they can only do so much. With that in mind, we attempted to choose the “better face” when laying out our deck boards. I think the healthy approach (when installing any wood decking board) is to expect that a few boards might have issues, and be prepared to replace them if necessary. 

Spacing and alignment of appearance-grade treated boards 

We chose to space the boards using an 1/8” shim. In hindsight, we did not give this a great deal of thought, and it will be interesting to see how it works out.  I think the main driver was that we don’t really have access under this part of the deck and wanted to limit the amount of debris that can fall through the spacing.

We were able to position most of the boards pretty easily, but we did use a clamp for a few of them. This allowed us to “pull” a board into place to achieve our desired spacing. Our clamp was too short once we got a certain number of boards installed. At that point, we reconfigured the clamp and used it as a spreader, which allowed us to push boards into shape by positioning one end against the horizontal blocking. 

Choosing the driver bit and fasteners for appearance-grade treated lumber 

We ended up using a Smart-Bit Pre-Drilling and Countersinking Tool that helped us set the screws at a predetermined depth. Once we adjusted it properly, this method was effective and didn’t leave any marks on the surface of the decking boards. 

We chose to use 3” flat-head exterior screws to fasten the decking boards. (In this case, holding power won out over aesthetics.) We like to use the Screw Products brand, as they do a good job of pulling the deck board down tight against the joist.   

We currently have our small deck section mostly covered up to protect it from being damaged during construction of other projects that are happening simultaneously. Once the deck is back to “normal exposure,” we'll monitor its performance and report back in a future blog. Stay tuned!