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What is a Gambrel Roof Calculator?

A Gambrel Roof Calculator estimates the number of trusses, rafter lengths, roof area, and material requirements for a gambrel roof based on its dimensions, pitches, and truss spacing. Gambrel roofs have two slopes on each side, with a steeper lower slope and a shallower upper slope, commonly used in barns for extra attic space.

This calculator assumes a standard gambrel roof design and includes a waste factor for lumber estimates. It is ideal for barns, sheds, or homes requiring additional headroom.

Classic Gambrel vs. Mansard vs. Dormer Gambrel

How to Use the Gambrel Roof Calculator

1. Building Width: Enter the width of the building (distance between exterior walls).
2. Building Length: Input the length of the building along the ridge.
3. Lower Roof Pitch: Enter the lower roof pitch angle (e.g., 60 degrees).
4. Upper Roof Pitch: Enter the upper roof pitch angle (e.g., 30 degrees).
5. Truss Spacing: Select the spacing between trusses (e.g., 24 inches on center).
6. Overhang: Enter the overhang length for eaves and gables.
7. Unit: Choose the unit of measurement (feet or meters).
8. Calculate: Determine the number of trusses, rafter lengths, roof area, and estimated lumber requirements.

Lumber Requirements by Gambrel Roof Configuration (Board Feet)

Comparison based on a 24 ft width and 24-inch spacing

Additional Information for Gambrel Roof Planning

Design Considerations: Ensure proper load-bearing capacity (e.g., snow load, wind load) and consult local building codes for truss and rafter specifications.

Cost Factors: Gambrel roof costs vary by material (wood vs. steel), pitches, and complexity. On average, wood trusses cost $5-10 per linear foot of span.

Installation Tips: Use professional installers for safety. Pre-fabricated trusses reduce labor but require precise measurements. Consider dormers for added light and space.

Frequently Asked Questions (FAQ)

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