A shed roof is a single flat plane sloping in one direction, with no ridge, hip, or valley, resembling one half of a simple gable roof. It is common on additions, porches, and garages because it is simple to frame and quick to shingle, and its single slope drains cleanly to one edge as long as that slope is steep enough to move water. A shed roof built at too low a pitch behaves more like a flat roof and needs low-slope materials instead of standard shingles.
A shed roof is roofing at its simplest: one flat plane, sloped in a single direction from a high edge to a low edge, with none of the ridges, hips, or valleys that more complex roof shapes create.
That simplicity is exactly why it shows up so often on additions, porches, carports, and detached garages, where tying into a slightly lower or offset structure with a full gable or hip roof would be needlessly complicated. It is also a defining feature of a lot of modern and minimalist home design, where a single dramatic slope is used as an intentional architectural statement rather than a practical afterthought.
Because there is only one plane and no internal seams to flash, a shed roof is comparatively fast and inexpensive to frame and cover, and it has fewer of the leak-prone junctions that valleys and hips create on more complex roofs.
The pitch of that single slope is what determines how it needs to be built. A shed roof pitched steeply enough sheds water the same way any sloped roof does and can be covered in standard shingles or metal.
A shed roof built at a shallow pitch, which is common on additions where headroom is tight, behaves much more like a flat roof. Water sits on it longer, and it needs low-slope materials and detailing, such as a membrane system, rather than shingles rated for a steeper slope.
The number that actually matters is the pitch itself. A steep enough shed roof performs like any sloped roof; a shallow one needs to be priced, built, and maintained as a low-slope system regardless of how the framing looks from the ground.
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