I am planning to reinforce my deck, as it is has a lot of sway, and was built with 12' 4x4s, and not 6x6s. The deck spans my driveway, which is the width of a two car garage, so a fairly decent span. Should I look at installing some type of braces for this span, or will posts on either side of the driveway be enough?
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You can install bracing from 4' down on the post at a 45degree angle to the bottom of the header that is so panning the driveway. Use 1/2" x 6" lags to make the connection thru the new 4 x 4 bracing. Make sure that the brace doesn't interfere with getting a car in and out of the garage
Use wood or metal strapping diagonally along the bottom of the joists.