I would like to put a roof over my deck. The deck is 12'x16'.Support post are 4x4.My house is a two story with a cantalever extendeing over the deck about foot and a half.The deck extends 12' out from the house and 16'along the house. It has 3 support post.Is this enough to support a roof and do I need to change these to 6x6's.Also what size roof raters do I need to use? Do I use the 1/4" per foot for roof pitch? How do I attach the lumber that supports the roof rafters to the house and the support post.Thanks roofless in Arnold MO.