Can I span 19' 4' with a metal beam?
I have a corrugated plastic patio cover that is built over 2x6 fir joists anchored to the house ledger and carried by a double 2x6 beam which is in turn supported by three 3x3 fir posts (posts are actually 3x3). The two outside posts are 19' 4" center to center and the beam cantilevers approximately four inches past each end post. Can I replace the wooden beam with a metal one and eliminate the middle post? If it is possible, what size beam do I need to use? Aluminum? Steel? There is no live load and we rarely get snow. I do not know what the dead load is, but it is not much as I can easily lift the existing beam easily.