Gable or lean-to: compare the same shed footprint
A gable has two roof slopes meeting at a ridge. A lean-to has one slope. Neither is automatically cheaper or suitable for your site: compare the roof span, height and openings using the same footprint first.
Same settings, one roof-style change
Both examples have a 12-foot front and 8-foot depth (96 square feet), 3/12 pitch, 97.125-inch base framed wall height, treated skids on gravel, front double door (62 × 80-inch rough opening), no windows, LP SmartSide siding, asphalt shingles, moderate snow setting and 6-inch overhang. Only roof style changes. These are permitted generator inputs, not an engineer’s approval.
| Output | Gable | Lean-to |
|---|---|---|
| Floor area | 96 sq ft | 96 sq ft |
| Roof area | 123 sq ft | 124 sq ft |
| Overall height | 11' 3/8" | 11' 8-1/4" |
| Boards to buy | 108 | 91 |
| Sheets to buy | 22 | 22 |
| Required materials estimate | $3,414 | $3,356 |
Where the roof drains, and which wall is high
The gable ridge runs front to back. Its roof falls to the left and right sides, so allow access along both eaves. The lean-to’s high wall is the front door wall, and its roof falls toward the back across the depth. Plan access at that low edge for water collection and maintenance; do not direct runoff onto a neighboring lot or assume it can connect to a house roof.
Why the counts change
The gable’s rafters span half the front width on each slope, while the lean-to rafters span the full depth. The ridge, ties, tall-wall studs and sheet layouts differ, so the generator recalculates them rather than rotating a fixed materials list. Equal floor area does not mean equal roof area, height or board count. Roof area is rounded to square feet in this table.
The material estimates above are calculated from built-in 2025–26 US prices. Optional items, labor, tools, permits, tax and delivery are excluded; local quotes can change the price difference. The table demonstrates this configuration, not a universal saving for one roof style.
Calculate this gable or calculate this lean-to. Change the options for your own site and compare the new lists. The calculator guide explains cut pieces, purchased boards and waste.
Before choosing a roof
Measure the front-door approach, available height and drainage space. Verify property setbacks, HOA rules, permits, local wind/snow loads, foundation and roofing manufacturer requirements with your building department and a qualified builder or engineer. These examples are freestanding; attaching either to a building requires separate professional review. Plans are a guide, not stamped engineering drawings.
For orientation examples, see 10x14 versus 14x10 gable plans and the 8x12 lean-to with a 12-foot front. The free list comes first; complete custom plans are optional.