I have a 3'x3' - 20 PSI polyiso insulation board that I will be putting a 3x3 concrete paver and A/C unit on. How can I figure the total weight that the insulation board can hold before it gives. Here is what I figured.
36"x36" = 1296 sq inch footprint
20 pounds per square inch x 1296 sq inches = 25,950lbs
Is this right? That seems way too high. Can someone help