Mike Cantrell wrote:Bearing on the concrete pad makes me nervous. I've seen that plan go badly. (Second story room gradually sagging off of the side of the house. In, fact, it was a very similar situation, along the length of a hill. The pad had been poured just for walking, and so there was no effort made to keep it from sliding down the hill little by little. It wasn't supposed to be structural. As it crept down, the posts resting on it did too, and the room sitting on the posts.)
Do you know anything about it? Thickness? Type and quantity of reinforcement? Presence or absence of a footer underneath?
Brian Knight wrote:I would be mad too if I were expected to carry the loads of a green roof over those kinds of spans Its safe to say you will at the very least need to add some posts for the long span, keep your soil mix on the light weight side of the range, and get some lateral bracing into the mix. Try to find some expected weights of saturated soil mixes for green roofs, add in the snow loads for your area and compare that with the span tables for the lumber you picked out. It looks like your off to a good start!