What defines a roof for this credit? Is it slope, construction, or function? I have a project with a mansard roof. It has a 65% slope, very steep. I would count it as a roof, as it's construction is like a roof and is not vertical. But, one could argue that a mansard roof (the steep part anyway) functions programmatically more like a wall. Any thoughts? When does a wall become a roof (for LEED)?