James wrote:

Well, I must respectfully disagree. In addition to assurances from folks
here WHO HAVE DONE IT, as stated in my OP, I have walked on a floor made
with 2 X 10's spanning 16 feet. There was no bounce. Surely I can go
to 2 X 12's and span 4 more feet.

You seem to rely more on beliefs than code data. You find 2x10 ok for 16 feet -
how does that translate into 2x12s ok at 20 feet? He has pointed you to one set
of code limits and it shows your ideas are not satisfactory. What you need to
do now is check your local code and find out what the requirements are.

Where's Hammurabi when you need him?

Mike