Gambrel Roof Calculator

Calculate the total area of a gambrel (barn-style) roof with its dual-slope design — steep lower slopes and shallow upper slopes for maximum attic space.

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Gambrel Roof Dimensions

Enter dimensions — upper slope pitch can be adjusted

ft
ft
in

What Is a Gambrel Roof?

A gambrel roof is a symmetrical two-sided roof with two slopes on each side. The lower slope is steep (typically 60°) and the upper slope is shallower. This design maximizes usable attic/loft space and is iconic on barns and Dutch Colonial homes.

Gambrel Area = 2 × Length × (Lower Slope + Upper Slope)
Lower Slope: ~60° angle, covers 40% of half-width
Upper Slope: Configurable pitch, covers remaining 60%

Advantages

  • Maximum usable attic/loft space — nearly full second story
  • Classic architectural appeal
  • Can accommodate loft dormers for even more space

Considerations

  • Poor wind resistance — not suitable for hurricane zones
  • Upper/lower slope junction requires careful flashing
  • Snow can accumulate at the slope break point

📊 Roof Area

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Enter dimensions to calculate gambrel roof area.