Using a notched post and beam connection will lock the beam in place, secure it from rotating and resist wind uplift. Notching a post does not weaken the structural integrity of the wood support post because the load for the deck is transferred down through the post to the footings. The upright notched section of the post acts stabilizes the beam. Most deck builders use a reciprocating saw to cut an L shaped seat in the top of the post large enough to hold the beam. Another building method to consider if you don’t have a reciprocating saw involves using circular saw to score the top of the post to remove the weakened sections with a chisel. A 2-2x10 beam will require a notch 3” wide by 9-1/4 inches tall. To hold the beam in place you will then need to predrill and run two ½” threaded carriage bolts through the beam and the top of the notch.
Measure and mark the section of each 6x6 support post one at a time to cut away for the beam pocket.
Use a circular saw at its lowest cut depth to cut out the post notch. The circular saw will not finish the cut with 2 passes.
Use a reciprocating or hand saw to remove the shoulder notch and clean up any rough edges.
Apply a coat of copper naphthenate to all cut ends of the pressure treated 6x6 to prevent decay. Attach the post to your footing using a post beam connector.
Set your beam into the notched pocket and drill pilot holes for your through bolts set 2" from the top and bottom of the beam.