BIGmouthinDC, thank you for your feedback. I've read a lot of your input and seen your HT, BZ!
Have not determined the screen size (120-130-140) and projector TBD
(DLP-BENQ) for HDTV sports. There is a couch going in front of the riser, thus the 16' prime and the riser. My BAD for not inputting these elements.
Since it's an island riser will use; 30lbs roofing felt base, 2x12 perimeter and 2x8 stringers (saw your input), either rolled or lose insulation, 2-3/4 OSB with felt between, glued and screwed, with carpet & pad. Electrical conduit will be set into concrete when poured. Does this sound correct, what else?
The counter that occupies the rear 5' of riser is my building issue, how to build?? I like the rap-around solid front-side, but how to attach to riser? Top would be laminate something?