Triple beams for decks (3-2x's) should be supported with 6x6 posts using a post beam connector bracket. 4x4 posts will not provide adequate bearing for a triple beam. Do not notch the top of the post and through bolt the beam because the width of the triple beam will limit the notched section of the post down to 1". This does not provide enough strength to hold the beam in place. A positive connection using a post beam bracket installed on top of the post and nailed to the side of the beam is the most secure connection.
Triple Deck Beam to Post Connection
Here is an example of how to mount a 3-2x10 beam over a 6x6 support post to support a shed style porch roof.
