One plane, one slope, no valleys, no hips: the shed roof is the simplest roof a beginner can frame, and it looks sharp doing it. But simple is not the same as forgiving. The tall wall needs bracing, the low edge needs careful drainage, and the whole assembly has to resist racking in ways a gable never worries about.
Rafters, wall heights, drainage, and bracing: the single-slope system is detailed end to end. You will learn rafter sizing, the high-wall and low-wall details, drip-edge and drainage sequencing, and the slope minimums that keep water moving. Simple roof, deliberate details.
One Slope, Zero Excuses
The shed roof — a single plane sloping one direction — is the simplest roof to frame, the cheapest to build, and a favorite for modern tiny houses. But simple doesn’t mean careless: the high wall, the drainage, and the racking resistance all need deliberate design. This guide frames the shed roof properly.
1. Why the Shed Roof Suits Tiny Houses
Simplicity: one plane, one ridge height difference, no valleys, no hips (the framing is rafters + two wall heights — a beginner can frame it). Cost: 20–30% less roofing material and labor than a gable (fewer cuts, less waste, faster). Modern aesthetic: the high-low profile reads contemporary (clerestory windows under the high side — the signature move). Loft space: the high side buys headroom where it matters (sleeping loft under the tall wall — the efficient use of the 13’6″ height limit). Solar: one big unbroken plane facing the sun (the ideal solar roof — no dormers, no shading from a second slope).
2. Pitch and Height: The Governing Numbers
Minimum pitch: 3:12 for shingles (below that, use standing-seam metal or membrane — shingles leak on low slopes). Sweet spot: 4:12 to 6:12 (steep enough to shed snow and look intentional, shallow enough to keep the high wall manageable). Height math: on a 28-ft house at 5:12 pitch, the high wall is ~11.7 feet taller than the low wall — that differential must fit under 13’6″ total (low wall 8 ft + 11.7 ft rise = 19.7 ft — TOO TALL; so either shorten the span, lower the pitch, or accept a shorter low wall). The design loop: pick the low wall height (7–8 ft), pick the pitch, compute the high wall, verify total under 13’6″ — iterate until it fits. Snow country: steeper is better (6:12+ sheds snow; 3:12 holds it — the structural load difference is enormous).
3. Framing the Rafters
Rafter sizing: 2×8 minimum for spans to 12 feet (2×10 for 12–16 feet or heavy snow — span tables govern; the single slope means every rafter spans wall to wall). Birdsmouth: cut at both ends (the seat cut on the wall plates — maximum 1/3 of rafter depth; the birdsmouth is the connection). Spacing: 16″ on center standard (24″ OC works with thicker sheathing — the weight-saving option). Ridge beam vs ridge board: with a shed roof there’s no ridge — the HIGH END needs a beam (the rafters’ top ends bear on the high wall’s top plate — that plate carries half the roof load; double it or use an LVL for long spans). Collar ties: not applicable (no opposing rafters) — but the high wall needs lateral bracing (see section 5).
4. The High Wall: The Structural Challenge
The tall wall is the shed roof’s engineering crux: it’s a tall shear wall (11–13 feet of stud — it wants to rack and bow; sheath it fully, inside and out if needed). Studs: 2×6 minimum (2×4 studs at 12+ feet are too slender — they bow; use 2×6 or engineered studs). Mid-height blocking: horizontal blocking at midspan (prevents stud bowing — the fire-blocking doubles as structural). Top plate: doubled, lapped at corners (the beam carrying the rafters — size it for the load). Hold-downs: at the high wall ends (wind uplift on the tall wall is severe — Simpson hold-downs to the floor frame, not just nails).
5. Racking: Bracing the Single Slope
A shed roof has no opposing slope to triangulate — bracing is critical: roof sheathing: full structural sheathing glued and nailed (the roof diaphragm — it resists racking of the whole box; the nailing schedule matters doubly here). High-wall bracing: the tall wall gets diagonal bracing or full sheathing both sides (it’s the weak axis). Hurricane ties: every rafter to both plates (uplift on a single slope is asymmetric — the windward edge tries to peel; tie every connection). Longitudinal bracing: the end walls carry the longitudinal shear (sheath them fully — they’re the bookends holding the tall wall plumb).
6. Drainage: One Gutter, Done Right
All the water goes one direction — manage it: gutter: oversized (6″ K-style minimum — the single gutter handles the entire roof’s runoff; 5″ gutters overflow in real rain). Downspouts: two minimum (one at each end — a single downspout clogs and the gutter becomes a waterfall). Drip edge: on all edges (the low edge especially — water must launch clear of the wall, not curl back under). High-side flashing: where the roof meets the high wall (the headwall flashing — stepped or continuous, lapped under the wall WRB — the leak point amateurs miss). Ground: splash blocks or drainage (the concentrated runoff at the low side needs somewhere to go — grade away, or collect it in rain barrels — the shed roof is a rainwater harvester’s dream: one gutter, one downspout manifold, one tank).
7. Roofing Material for the Single Slope
Standing-seam metal: the best choice (lifespan 50+ years, sheds snow, works at 3:12, the modern look — $4–7/sq ft installed). Membrane (TPO/EPDM): for low slopes under 3:12 (the flat-roof solution — fully adhered, 20-year life). Shingles: fine at 4:12+ (cheapest — $2–4/sq ft — but heavier and shorter-lived than metal). Underlayment: full ice-and-water shield (the single slope means any leak runs the full length — belt-and-suspenders underlayment is cheap insurance).
Final Considerations
Run the height math first (low wall + pitch × span must clear 13’6″), frame the tall wall like the shear wall it is, sheath and tie the roof diaphragm thoroughly, oversize the single gutter, flash the headwall meticulously, and roof it in standing-seam metal. The shed roof is the simplest roof — which means every detail is visible. Frame it right and its simplicity becomes its beauty.