I'm getting ready to build a deck. It will be 20' wide (attached to a ledger board) x 16' deep with 2 beams under it. There will be a beam at 7' from the house and a beam at 14' from the house. There will be a 2' overhang. It will be 8' high and I plan to park 2 cars under it. With that requirement I plan to use a 24 footer at 7' and a 26 footer at 14' with no center posts so there will not be anything to hit with a car! I have 3 questions:

1. Having looked into Rosboro Treated Glulams, what size beams are needed with a code requirement of 40 lb live and 10 lb dead (50 lbs. per sq. ft.)and an Upstate New York location.

2. Due to the high cost of Treated Glulams, could I build up my own 2x12 pressure treated southern pine beams that would be strong enough to do the job, how big would they have to be, and would they be cost effective?

3. How about steel beams? What size and how do they compare in price to the other options?