Barn & Gambrel Roof Calculator

Two-Pitch Area & Materials for Gambrel Roofs

The Barn / Gambrel Roof Calculator handles two-pitch barn-style roofs with separate upper and lower slope angles. Enter the building footprint, the upper pitch (typically shallow, 6/12-9/12), and the lower pitch (typically steep, 18/12-24/12), and the tool returns total roof surface area, shingle bundle count, and underlayment rolls. Gambrel roofs maximize loft headroom in barns and Dutch Colonial homes but require careful estimating because of the dramatic pitch change.