Options for Fastening Beams to Deck Posts
Get an overview of post-to-beam hardware choices for single, double, and triple beams.
Like a post base to footing connector the post to beam connector (post cap) resists lateral load forces that could knock the post out from under the beam and uplift forces. Post caps straddle both the top of the post and the bottom of the beam. Most are formed as one piece and must be installed on the post before the beam is placed. Some can be installed after the post and beam are attached and are usually used in pairs – one on each side of the post.
Choose the right size hardware for your beam
Post caps are sized for 4×4 and 6×6 posts at one end. The other end is sized for either a full 4x or 6x beam, or a built-up beam (double or triple 2x). Since the size of the top is determined when the hardware is fabricated, you have to order the correct size to match the beam size required for the deck. You can’t bend the flanges wider or crush them closed to fit lumber they aren’t designed for. The models designed to be installed after the beam is installed may only work on one face of the beam/post and not the other because the opposite faces aren’t in plane.
Brace to resist twisting
Post caps provide only limited resistance to beam rotation. Because of this, you may need to either diagonally brace the bottom of the beam or top of the post to the deck joists or screw or bolt a splice block alongside one face of the beam and extending down an equal amount down the side of the post.
Since we focused on hardware connections, the video doesn’t profile a connection illustrated in the 2018 IRC where a 6×6 post is notched 3 in. for a double 2x beam leaving a 2-1/2 in. leg that the beam plys can be bolted to.