If you definitely want to do it yourself there are a few others resources to try. The books listed earlier will help you learn about construction (and don’t forget Green Roof Plants by Edmund Snodgrass), but, as I recall, they do not have much about making a growing media for the plants. As you know, this is crucial. I would suggest checking out an e-book by Living Roofs (Livingroofs.org) for guidance and spending a significant time researching media on google for a good mix.
