Gable Siding Calculator
Accurately estimate the square footage and materials needed for your triangular gable ends.
Calculation Summary
Understanding Gable Siding Requirements
A gable is the generally triangular portion of a wall between the edges of intersecting roof pitches. Because of its shape, measuring and ordering siding for a gable is different than measuring a standard rectangular wall. Precise calculations are essential to avoid project delays or excessive leftover material.
The Mathematics of a Gable
Calculating the area of a gable follows the basic geometric formula for a triangle: Area = ½ × Base × Height. However, when siding a house, you must account for multiple gables and the "waste factor." Because siding panels are rectangular and gables are triangular, many diagonal cuts are required, leading to significantly higher waste (usually 10% to 20%) compared to standard walls.
How to Measure Your Gable
- The Base: Measure the horizontal distance along the bottom of the triangle (where the gable meets the main wall).
- The Height: Measure vertically from the center of the base to the highest point (the peak) of the roof.
- The Count: Note how many gables of this specific size your home has. Most homes have at least two.
Example Calculation
Suppose you have a gable with a Base Width of 20 feet and a Peak Height of 10 feet:
- Base Calculation: 0.5 × 20 ft × 10 ft = 100 square feet per gable.
- Total for 2 Gables: 200 square feet.
- Adding Waste (15%): 200 × 1.15 = 230 square feet.
- Siding Squares: 2.3 squares (since 1 square = 100 sq ft).
What is a "Square" in Siding?
In the construction and siding industry, the term "square" refers to an area of 100 square feet. If your total calculation comes to 350 square feet, you will need to order 3.5 squares of siding. Most retailers sell siding by the square or by the box (which typically covers half a square or a full square depending on the material).
Pro Tips for Accurate Ordering
- Waste Factor: For simple gables, 10% waste is usually sufficient. For steep pitches or complex designs with many cuts, 15% to 20% is recommended.
- Dormers: If you have small dormer gables, measure them separately and add them to your total.
- Overlap: Most siding area calculations account for the exposed face of the siding, but always check if your chosen material (like cedar shingles) requires a specific lap that changes coverage.