What Is a Structural Slope in Roofing? Let’s Break It Down! Ever hear someone say “flat roofs aren’t really flat”? They’re right and that’s where structural slope comes in. A structural slope is the built-in pitch of the building itself that helps water move off the roof. It’s created using sloped framing (like steel beams, bar joists, or angled wood) so that even before insulation or roofing goes on, the deck already has a slight incline. Why does this matter? Because on a flat roof, water is t