Roof Pitch & Types
Roof pitch is critical for material selection, water shedding, and structural load.
What is Pitch?
Expressed as a ratio of rise (vertical) over run (horizontal), usually per 12 inches. A 6:12 pitch rises 6 inches for every 12 inches of horizontal distance.
Material Requirements by Pitch
| Pitch Range | Suitable Materials | Notes |
|---|---|---|
| 0:12 - 2:12 (Flat/Low) | Membrane, EPDM, TPO, Built-up | Requires high waterproofing. No shingles. |
| 2:12 - 4:12 (Low) | Metal, Rolled Asphalt, Double Underlayment Shingles | Ice and water shield essential. |
| 4:12 - 9:12 (Conventional) | Asphalt Shingles, Wood Shakes, Tile | Standard application. |
| 9:12+ (Steep) | Shingles, Slate, Metal | Requires special installation harnesses. |
The Pitch Multiplier
To calculate actual roof area from a flat footprint, you must multiply by the pitch factor. A 6:12 roof has a multiplier of 1.118. A 1,000 sq ft footprint equals 1,118 sq ft of roof surface (plus overhangs).