Deck Beam to Post Connections
The Residential Structures Code provides only two methods for connecting a deck beam to a supporting post. Both methods are related to the requirement in section R507.7 that deck beams must have at least 1-1/2” bearing when supported on wood or metal and 3” when supported on concrete or masonry.
The first method described is to notch the post to accommodate the full width of the beam and bear fully on the notch of the post. The beam is secured to the post with two ½” diameter through-bolts with washers on each end (not carriage bolts). The part of the post to which the bolts are connected must be at least 2-1/2” thick. The supporting post would need to be at least a 4 x 6 to accommodate a two-ply beam and the required notch. This method would only work for a single-member or two-member beam.
The second method is to use a manufactured post-to-beam connector. This connector fits on top of and is secured to the post. It must be sized to fit both the post dimensions and the beam width. It is secured to both post and beam with connectors as designated by the post cap manufacturer. This method will accommodate a larger beam.
With either system the full width of the deck beam width must bear on the post. Each ply of a multiply beam must rest on the post.
Other methods of support can be used provided it is demonstrated they will make a connection which provides equivalent support and lateral restraint for the beam to transfer loads to the post and keep the beam securely anchored over the post. Bolting the beam to the side of the post may not provide an equivalent connection. If used, it would need to be demonstrated the size and number of bolts used have the strength to transfer all loads without shearing or splitting the wood.