Roofing Calculators
Gambrel Roof Area Calculator
Calculate the total area of a gambrel (barn-style) roof with separate upper and lower pitch inputs. Get results in square feet, square metres, and roofing squares with adjustable waste factor.
Enter Dimensions
Vertical height of the steep lower section
Results update automatically as you change inputs.
Gambrel Roof Cross-Section
Lower Slope Area (both sides)
0.00 m²
0.00 ft²
Upper Slope Area (both sides)
0.00 m²
0.00 ft²
Total Roof Area
0.00 m²
0.00 ft²
Total with Waste (15%)
0.00 m²
0.00 ft²
Roofing Squares
0.00
1 square = 100 ft² (9.29 m²)
Lower Slope Length
0.00 m
Upper Slope Length
0.00 m
Total Ridge Length
0.00 m
Calculation Breakdown
Mansard Roof Calculator
Calculate a four-sided mansard roof with separate upper and lower pitch inputs for all sides.
Calculate Mansard Roof →Gable Roof Calculator
Calculate the area of a standard gable (A-frame) roof from building dimensions and pitch.
Calculate Gable Roof →All Roofing Calculators
Browse our full suite of free roofing calculators for every roof type and measurement need.
View All Calculators →Frequently Asked Questions
Common questions about gambrel roofs and calculating their area
What is a gambrel roof?
A gambrel is a barn-style roof with two slopes on each side. The lower slope is steep (typically 60–70°), and the upper slope is much shallower (typically 20–30°). This design creates significantly more usable attic or loft space than a standard gable roof.
What’s the difference between gambrel and mansard?
A gambrel has two sides (like a gable), while a mansard has four sides (like a hip roof). Both use double slopes with a steep lower section and a shallower upper section, but the mansard wraps around the entire building perimeter.
What angles work best for a gambrel roof?
The lower slope is typically 60–70° and the upper slope 20–30°. The steeper the lower slope, the more headroom you get in the attic or loft. A 60° lower / 22° upper combination is a very common starting point.
Are gambrel roofs good for sheds?
Yes, gambrel roofs maximise storage space in sheds and barns. The steep lower slope creates usable wall height inside the building, and the shallow upper slope covers the remaining width efficiently without excessive overall roof height.
Can I add a gambrel roof to my existing building?
It requires significant structural work including new rafters and potentially reinforced walls to handle the different load distribution. Council approval is typically needed, and you should have an engineer verify the design before proceeding.
Need a Quote for Your Gambrel Roof?
Gambrel roofs need careful engineering. Our team has experience with barn and rural building roofing across the Barossa Valley.