Hi im looking for help on planning a covered patio to a 18x16 Deck I plan on adding to my house. The deck will be 18' wide and extend out 16' from the house. I want to build a patio extending out 12' from the house and have atleast a 1' overhand on each side making the patio cover 12x20. I plan on using Polygal as roofing so it does not need to support much weight. Building in a location that does not experience snow. What size post and beam do I need to use to span the 18' between support post? attached is a image of the concept design i made. [![Deck Concept Photo][1]][1]


  [1]: https://i.sstatic.net/aqozf.jpg