Grew up with carpet and even carpet padding stapled to the backs of platforms and dutchman covered platforms with carpet padding under the muslin cover. Both were ratty in ripping or coming loose but structurally sound as long as the stud connections stayed together. Later in an earlier college I moved onto a system similar to yours but found that there was problems in our case of the ½" black fiber Celotex panels providing just enough gap that it allowed for extra sheer of the screws attaching top to rails. Could be a difference of #8 drywall screws these days verses the #6 I remember back than for such a length. Didn’t like that method either. Even seen some places that used fiberglass insulation under the platform which does have a much better STC value than all but is even less portable or easy to use.
At CSSI we used 5/4x6 poplar to make the frames and did not use padding, also the corners were supported by aluminum corner blocks designed to support and allow for up to 18" 2x4 legs. The corner brace support structures added to the under side of the platform added to support and reinforcement of the corner so they would not come apart. But such platforms were not padded.
In another college we built a stock glued platform where the glue bonds plywood to frame this does not in being a problem both for strength and for keeping it together but added the Celotex above the plywood with a Hardboard top to it. Worked well, a bit more heavy and the tops were less so than above prone to also sheer of it or damage. Frame was normally good, just the top with problems.
Kind of preferred this method in structure than padding.
Wondering if such a Celotex platform type might while less sound and shock absorbing, be better if attached under the platform in allowing the framing to be glued? This especially with corner block of some sort to reinforce it?
Granted legging if soft surface under it would be less efficient unless welded top plate corner block a leg fits into.
Good truss leg the truss leg system, certainly saves time over the countersunk sway brace truss legging I worked for in a third scene shop that used. On the other hand a bit more heavy unless ½" plywood. I tended in my own use to use the trussed legging other than for a single platform for the long run as a long and not duplicated between platforms sections all individual platforms more text book rested upon. Certainly easier to mount the truss first than install the platforms on it than as if individual platforms have a lot of extra support truss and all individual to each platform.
For legs, if say 18" or up to 36" leg, I might do a 2x4 with variable length 3/4" plywood double corner block pre-glued to it as wings. As opposed to a bunch of bullet holes in a 2x4 leg and what screwed into for weakening it, the 3/4" plywood corner block allowed for lots of re-use of hole or room for new holes and also a better distribution of places to screw into for fresh holes.
General concept is after 18", you need bracing. In my case after 12" for say ½" plywood I did bracing and had pre-cut legs with wings already installed. Up to 36" with a 18" or 24" corner brace in bringing it back down to 18" unsupported length, all I had to do was screw in the leg.
After that, I normally trussed the thing in while it took more time perhaps, it took a lot less under the platform in shimming etc. afterwards. Trussed the whole thing on like 48" centers. Easier also to truss the whole platform especially if a rake than to truss each platform individually.
On sound proof platforms if doing so, wonder how well in general a stress skin panel would do and how to work with such a thing if other than truss legging. I would think it the best and even lightest method of doing it. But also probably the most expensive way of doing it.
At CSSI we used 5/4x6 poplar to make the frames and did not use padding, also the corners were supported by aluminum corner blocks designed to support and allow for up to 18" 2x4 legs. The corner brace support structures added to the under side of the platform added to support and reinforcement of the corner so they would not come apart. But such platforms were not padded.
In another college we built a stock glued platform where the glue bonds plywood to frame this does not in being a problem both for strength and for keeping it together but added the Celotex above the plywood with a Hardboard top to it. Worked well, a bit more heavy and the tops were less so than above prone to also sheer of it or damage. Frame was normally good, just the top with problems.
Kind of preferred this method in structure than padding.
Wondering if such a Celotex platform type might while less sound and shock absorbing, be better if attached under the platform in allowing the framing to be glued? This especially with corner block of some sort to reinforce it?
Granted legging if soft surface under it would be less efficient unless welded top plate corner block a leg fits into.
Good truss leg the truss leg system, certainly saves time over the countersunk sway brace truss legging I worked for in a third scene shop that used. On the other hand a bit more heavy unless ½" plywood. I tended in my own use to use the trussed legging other than for a single platform for the long run as a long and not duplicated between platforms sections all individual platforms more text book rested upon. Certainly easier to mount the truss first than install the platforms on it than as if individual platforms have a lot of extra support truss and all individual to each platform.
For legs, if say 18" or up to 36" leg, I might do a 2x4 with variable length 3/4" plywood double corner block pre-glued to it as wings. As opposed to a bunch of bullet holes in a 2x4 leg and what screwed into for weakening it, the 3/4" plywood corner block allowed for lots of re-use of hole or room for new holes and also a better distribution of places to screw into for fresh holes.
General concept is after 18", you need bracing. In my case after 12" for say ½" plywood I did bracing and had pre-cut legs with wings already installed. Up to 36" with a 18" or 24" corner brace in bringing it back down to 18" unsupported length, all I had to do was screw in the leg.
After that, I normally trussed the thing in while it took more time perhaps, it took a lot less under the platform in shimming etc. afterwards. Trussed the whole thing on like 48" centers. Easier also to truss the whole platform especially if a rake than to truss each platform individually.
On sound proof platforms if doing so, wonder how well in general a stress skin panel would do and how to work with such a thing if other than truss legging. I would think it the best and even lightest method of doing it. But also probably the most expensive way of doing it.