Roof squares are based on roof surface area, not just plan area, so pitch and overhang change the ordering math quickly. Construction Pro's Roof Estimator turns building dimensions, pitch, overhang, and waste into squares, bundles, sheathing counts, and rafter length on one screen.
This screenshot is taken from the small house roof takeoff recording that matches this article.
Ordering by plan area instead of sloped roof area is one of the quickest ways to underbuy shingles. These checks help during early takeoff, change orders, and last-minute bundle counts before a delivery call.
The numbers below match the current Roof Estimator logic used inside Construction Pro.
Example 1
Inputs: 30 ft x 40 ft, 6:12 pitch, 0 in overhang.
On a simple house roof, the app calculates about 1,341.6 sq ft of roof area, which equals 13.42 squares and about 41 bundles. This is a clean reminder that a 1,200 sq ft plan rectangle grows once the slope is applied.
Example 2
Inputs: 24 ft x 32 ft, 5:12 pitch, 12 in overhang.
Overhang changes both the effective width and the effective length, so it belongs in the estimator before the square count is trusted. The result is about 957.7 sq ft, or 9.58 squares, which rounds to about 29 bundles before any waste factor is added.
Example 3
Inputs: 20 ft x 28 ft, 4:12 pitch, 18 in overhang, 10% waste.
The base roof area comes out to about 751.6 sq ft, or 7.52 squares. After adding 10% waste, the ordering number becomes about 8.27 squares or 25 bundles. That is the figure to use for a safer order instead of the base area alone.
Common mistakes
Related guides
One roofing square equals 100 square feet of roof surface area.
Because overhang is usually measured that way in the field, and small entry mistakes there can distort the estimate fast.
Usually yes for ordering. The exact percentage depends on roof shape, cut complexity, and crew preference.
Construction Pro keeps roof area, order squares, bundle counts, and rafter length in one jobsite-friendly screen.