12/12 roof pitch numbers
| Measurement | Result |
|---|---|
| Angle | 45.00° |
| Percent grade | 100.00% |
| Pitch multiplier | 1.4142 |
| 1,500 sq ft house roof area | 2,121 sq ft |
| 2,000 sq ft house roof area | 2,828 sq ft |
| Walkability | Not normally walkable without fall protection |
| Material guidance | Shingles, metal, tile, or slate may work when the manufacturer allows it |
How the pitch changes the project
Pitch is more than a number on a listing. It changes the amount of roofing surface that must be covered, the way water moves toward the eaves, the amount of underlayment and finish material required, and the amount of fall-protection planning needed. A low slope may need a roofing system specifically approved for low-slope drainage. A medium slope often works with common shingle or metal systems. A steep slope can improve drainage but makes access and installation more demanding.
Choosing roofing materials
Shingles, metal, tile, or slate may work when the manufacturer allows it. The exact answer depends on the product’s published minimum slope, fastening method, underlayment requirements, climate, and local code. Do not choose a material from pitch alone. Check the installation instructions for the exact product and ask a qualified roofer when the roof is steep, complex, or difficult to access.
Frequently asked questions
What does 12/12 mean?
It means the roof rises 12 inches over every 12 inches of horizontal run.
Does the multiplier include overhangs or dormers?
No. It converts a measured horizontal roof footprint into an estimated sloped area. Overhangs, valleys, dormers, hips, and waste should be measured or allowed for separately.