Cathedral Wall Square Footage Calculator

Calculate the total area of a gable or cathedral wall — a rectangle topped with a triangular peak. Perfect for painting, drywall, and siding projects.

Cathedral Wall Calculator
Rectangle Area
160
sq ft
Triangle Area
60
sq ft
Total Area
220
sq ft

What is Cathedral Wall Square Footage Calculator?

A cathedral wall square footage calculator computes the total area of a gable-end or cathedral wall — a wall consisting of a rectangular lower section topped with a triangular peak that follows the roof pitch. This combined shape is common in houses, churches, barns, and A-frame structures.

This tool exists because cathedral walls are not standard rectangles and require splitting into two shapes for accurate measurement. Underestimating the triangular peak area is a common mistake that leads to material shortages for painting, drywall, and siding projects.

Cathedral Wall Square Footage Calculator Formula

Total = (Width × Wall Height) + (½ × Width × Peak Height)

Rectangle: Width × Wall Height = 20 × 8 = 160 sq ft.

Triangle: ½ × Width × Peak Height = ½ × 20 × 6 = 60 sq ft.

Total: 160 + 60 = 220 sq ft.

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Frequently Asked Questions

What is a cathedral wall?
A cathedral wall (also called a gable wall) is a wall shaped like a house gable — a rectangular lower section topped with a triangular peak that follows the roofline. The total area is the sum of the rectangle area and triangle area.
How do I calculate the area of a gable wall?
Split the wall into two shapes: the rectangular lower section (Width × Wall Height) and the triangular peak above (½ × Width × Peak Height). Add both areas together for the total wall square footage.
How much paint do I need for a cathedral wall?
Calculate the total wall area using this tool, subtract windows and doors, then divide by paint coverage (350 sq ft/gallon). A 20 ft wide gable wall with 8 ft wall height and 6 ft peak = 220 sq ft = about 0.63 gallons per coat.
How do I measure the peak height of a gable wall?
The peak height is measured from the top of the rectangular wall section straight up to the apex of the triangle. If you cannot measure directly, calculate it from the roof pitch: Peak Height = (Width / 2) × (Rise / Run).
How many sheets of drywall for a cathedral wall?
Calculate the total wall area, add 15% waste (cathedral walls have more cuts), then divide by 32 (for 4×8 sheets). A 220 sq ft gable wall needs: 220 × 1.15 ÷ 32 = 8 sheets of drywall.