12×20 Gable Large Shed Plans

About This Design

At 240 square feet, the 12×20 crosses the line from backyard shed into genuine outbuilding territory. This is a building with room for a full workshop at one end and dedicated equipment storage at the other — or a single-purpose space big enough to hold a boat, two motorcycles, or a compact tractor with implements.

The 12-foot width gives you the structural advantages of standard lumber sizing while the 20-foot depth provides the run you need for a workbench along a side wall with a table saw outfeed table behind it. Five windows — two spaced along the east wall, one each on the west, north, and south ends — provide generous natural light throughout a deep floor plan that would otherwise develop dark zones.

The 64-inch double-door entry handles any residential equipment and most small commercial loads. With 8-foot walls and a 6/12 gable, the ridge peaks at roughly 14 feet — tall enough for overhead storage and a pendant shop light layout.

Key Features

• 240 sq ft floor area — genuine workshop + storage combination
• 64" double-door entry handles boats, tractors, and sheet goods
• Five windows for natural light throughout the 20' depth
• 6/12 gable roof with ridge at ~14' for overhead storage
• 8' walls provide clearance for tall equipment and wall cabinets
• 20' depth creates natural zones for work and storage

Build Notes

A 12×20 demands a solid foundation. Five 4×6 pressure-treated skids running the 20-foot direction, spaced at 3 feet on center, support 2×6 floor joists at 16-inch spacing. At 3-foot spans between skids, the floor is essentially rock-solid.

Frame with 2×4 studs at 16 inches on center. The 20-foot side walls require a splice in the top and bottom plates — stagger the splice points so they never align, and back each splice with a 4-foot plate behind the joint. The double-door header is a 3-ply 2×10 or LVL.

At 12 feet wide, use 2×6 rafters at 24-inch spacing. The 20-foot length means 10 rafter pairs plus gable framing — a significant amount of lumber. Collar ties at every other pair are essential at this building length to prevent ridge sag. Consider blocking between rafters at the top plate to prevent wind-driven lateral movement.

Best For

The 12×20 is for the homeowner who has outgrown a standard shed. Workshop users get a dedicated bench area with power tools and a separate zone for materials and finished projects. Equipment storage handles a riding mower, snowblower, trailer, and seasonal gear without cramming. It doubles as a small boat house for vessels up to 18 feet, or a dedicated motorcycle garage with room for two bikes and a lift.