What are you trying to accomplish with the straps? Are you trying to hold it down in a hurricane? How tall is the building? What kind of "sail area" does it present to the wind? Etc, etc. There are mnany variables here, and thus it's a complex equation with no simple answer. I've said this before, and I'll probably say it again: The stakes are high. If you're looking to save a few bucks by getting some free advice on this forum, you're sure to get you're money's worth. My adivce is to hire a professional engineer to do the math for you to meet the codes and satisfy your building inspector. CB.
