I am in the building stage of my HT, and still in the framing portion. I'm about 80% finished with framing. I am going to build a riser for the second row of seating, and I would like to build a stage underneath the screen which will be about 25 or so inches from the floor. My questions: 1. Should I wait and build the riser and stage after the drwall is completed? This would allow me to make it more snug, and I won't have to deal with tripping on these risers during the drywall phase. 2. Should I try to fasten the drwall to the concrete floor? Or should I put a layer of felt down, and then make my frame out of 2X6 and then the plywood. Will the weight of the plywood be enough to keep the riser from moving? The stage area will probably have to be fastened somhow as there will be nothing on it. 3. Is it really necessary to fill the riser and stage area with sand? Or, can I use insulation and pack it in there tight? If so, how do you ensure that the sand won't start seeping out the bottom of the riser? Sorry for the long questions. I'd greatly appreciate any help anyone could offer. I will put some pics up soon.