12x20 Gambrel Barn Shed

Maximum Storage per Square Foot

This 12x20 gambrel barn shed gives you 240 square feet on the ground floor plus a full-width loft overhead — the gambrel (barn) roof is the shape that buys the most usable volume of any shed. The roof breaks at a knuckle into a steep lower slope and a shallow upper slope on each side, so the walls of the loft stand nearly vertical and the headroom stays usable right out to the edges. A 6-foot pair of battened double barn doors on the gable end handles mowers, quads, and bulky gear, while a loft window in the gambrel peak lights the space above.

Framing & Structure

The walls are framed from 2x4 studs at 16 inches on center with 4x4 corner posts on a 4-inch concrete slab. The roof is built from eleven gambrel trusses — each made from four 2x6 rafters joined with plywood gussets at the knuckles and peak — with 2x6 loft joists forming the loft floor. The double-door opening is spanned by a doubled 2x8 header, and framing anchors tie every truss down to the walls.

Finish & Loft

Cedar lap siding, corner boards, a base skirt, and gambrel rake boards give the barn its classic look, and the loft floor is decked in 3/4-inch plywood ready for storage. The included plan set shows every exterior face — front, back, and both gable ends — plus a dimensioned floor plan, all generated from a true 3D model so the drawings match what you build.