Roof Surface Area

Simple gable/shed surface area = footprint × √(1 + grade²). Pitch 6:12 is grade 0.5. No waste factor.

Construction & Trades

Simple gable/shed surface area = footprint × √(1 + grade²). Pitch 6:12 is grade 0.5. No waste factor.

App id: ROOF-03. Reference version 1.0.

How to fill it

Fill the inputs. The tool shows the outputs.

On the tool screen, Calc is the working sheet. Presets stores values you reuse. Reference is the formula, assumptions, and provenance below.

Formula

A = L W √(1 + (pitch/12)²)

Inputs

Name	Unit
Building length	`ft`
Building width	`ft`
Pitch (rise per 12) (optional)	`1`
Slope (optional)	`%`

Outputs

Name	Unit
Roof area (hero result)	`ft2`
Footprint	`ft2`
Slope factor	`1`

Diagnose

Observations are context. They do not pass or fail a structure. See Diagnose.

When	Observation	Severity
`\|Pitch (rise per 12)\| ≥ 12`	Steep roof pitch	caution

Provenance

Symmetrical gable without overhang. 20×30 ft at 6:12 is 600 ft² × √1.25, not 1,000 ft².