No. A roof structure is an open structure. It acts like an umbrella. Wind can get up and under the roof. Roofs/arbors/pergolas/gazebos use heavy posts to support the weight of the roof. These posts need to be fixed securely on both ends to prevent any lateral movement. There is no way to make the required fixed connection to the 2"x6" support board. We recommend that you place the posts for these structures into concrete frost footings and build the deck around the posts. Keep the two structures independent of each other, since one structure will be frost protected and the other will not.