Q. In his presentation on guard-post-to-framing connection methods, Mike Guertin offers many solutions that involve blocking, but makes no mention of water. My rule of thumb when building decks has always been this: At any point where two pieces of wood touch each other, air must be no more than 2 inches away. This would eliminate at least half of the connection details in Mike’s presentation. Is there a workaround?
A. Mike Guertin, remodeler, builder and regular presenter at JLC Live and Deck Expo, responds: I agree that leaving an air space is the best way to let deck components dry. The challenge, of course, is how to design details where you get the structural integrity required and still allow air to flow through the assembly and dry it out. In my experience, there’s no way to completely eliminate wood-to-wood joints on a deck. For example, think of the ends of joists butting up against a ledger, or a built-up beam, or a beam bearing on a 6×6 post, or even a 4×4 guard post in contact with a rim or joist. Those surfaces will – by necessity – be in contact.
In some cases, flashing membranes can be installed to limit the moisture entering a connection, but any time there is a vertical member such as a post, this solution isn’t very practical. I would be very interested in seeing an approach for securing a guard post to the deck frame that would meet the 500-lb. and 600-lb. load requirements set forth in AC174 and AC273 and that also allows for drainage. I’m always looking for better construction details that get us to code.