Load Bearing over Flat Roof of Room Addition
I own a house in El Cajon, CA-near San Diego. I recently came up with a scheme to use rainwater in my nearby garden. I have collected 110 gallons of water in 2 rain barrels from an overnight 1 1/2 inch rain fall. We have had a lot more rain recently but my barrels are at capacity.
I built a stand for my 2 55 gallon barrels and the combined weight of 918.5. The stand is built from 4 X 4s and 2 pressure treated plywood for the top surface. The plywood is 1/2 inch thick(I doubled them up for better weight bearing. I checked the stand after the rains and the stand is holding up fine with no sagging or other problem indications.
My scheme is to purchase a 275 gallon rectangular Tote. The Tote is 48" long by 39" wide. I calculated the pounds per square inch to be1.22662927.
The load pressure for my 55 gallons is 1.208130704.
You will notice that the load stats are very close between the rain barrels and the 275 gallon tote.
My question is based on what I relate do you think a tote situated at a corner just above my drain pipe(sitting above corner joists) would be a safe load). The tote will be supported by normally spaced studs. My rain barrels only had support from the outside periphery of the 4 X 8 top surface(no center support) yet no sign of sagging or stress.
I am not a carpenter or contractor. I need to decide soon, before the next rain whether to go ahead on my scheme. Rain will be coming according to forecasts.