There are times that tenons will get in the way of each other, weakening the entire joinery area. This issue can be particularly common on a queen post truss where the tie beam, rafter, and post collide. A double mortise and tenon on top of the queen posts can solve the problem and is the solution used in this instance.
Instead of a typical 2-inch tenon, two 1-1/2″ tenons are used on top of the post. They are spaced 1-1/2″ apart and are in line with the mortise on the tie beam. Two pegs hold the post to the tie beam.
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