Deck I Beam

[Bruce]

I want to make an 8' x 8' floating deck outside the front door. I have used several deck planning programs and the concensus is to use two 4" x 8" x 8' beams on two pier blocks each. The problem is that I can't get treated 4" x 8" wood beams. I could substitue 4" x 6" beams which are available, but I would rather use two I beams (for a variety of reasons). What size I beam would substitute for a 4" x 8" #2 treated wood beam?

[Rich]

I'm not an engineer so I should keep my mouth shut - :) but a W8x16 should do it with room to spare.