We own a 2 unit condo in San Francisco and are in the process of replacing our 30 year old tar and gravel roof. This project will happen in January. We had ideas to create a roof garden but our roofer Tom Lee is just doing the roof. How do we go about this? Do we need to find a landscaping person? Architect? Some special architect? We have a 3 year old and a dog and our condo doesn't provide outdoor space, that's why we thought this would be a good idea. Our downstairs owner is okay with us doing this as long as we do it right, etc... I wonder if there are architecture implications and whether we will have to touch the foundation or increase support capacity, how would we find out?