Now is the third time. You write, "I can't seem to find the load bearing capacity of perlite." The answer was partially addressed in the thread you started in March 2013. In that thread, Ron Keagle wrote, "I made some phone calls to the Perlite Institute and a few distributors with an inquiry about the possible use of Perlite concrete either as the footing, or as an independent layer beneath the concrete footing. All contacts told me that they have never heard of that being done and their immediate reaction was that Perlite concrete would not have the necessary compressive strength."