Day 81 - Here is a shot of the riser midway through it's construction today. The riser is 147" x 72" x 13". The perimeter was built with 2x12s and the joists are 2x8 with 12" OC. The riser is supported off of the concrete with 3/4 inch pieces of rubber cut from a thick entry mat. Only the corners and short ends are resting on the rubber pieces while the 12' long span is suspened to allow for more motion transfer from the Buttkicker tranducer I am attaching to the riser. The Buttkicker's job is to shake the entire riser - including the chairs on top of it - in concert with LFE effects. Not unlike those rides at a theme park. We also laid down 30# roofing felt underneath the riser to keep the fiberglass off the concrete and inside the riser.