I have a patio roof that is 24' long supported at each end and every 8' with a 4x4 post. I would like to remove one of the post's to create a roughly 16' space between the posts. The current beam support the 2x6' rafters is a double 2x4. What should I replace it with to support the 16' span? I live in western New York and the roof has a low pitch so snow of 12' on the roof are not unheard of. Thanks for any help you can give.