Rise and run describe roof pitch by comparing how much a roof rises vertically over a horizontal distance. In roofing, pitch is usually written as rise over 12 inches of run.
For example, a 4/12 roof rises 4 inches vertically for every 12 inches of horizontal run. A 12/12 roof rises 12 inches vertically for every 12 inches of horizontal run, which is much steeper.
Why It Matters
Roof pitch affects water drainage, material options, installation requirements, safety, and how a roof is measured. A 4/12 roof and a 12/12 roof may use similar materials, but they are very different to walk, stage, and install.
Common Problems
Common confusion includes mixing up slope and pitch, assuming all shingles work on all slopes, and misunderstanding why low-slope areas need different details.
Building Codes & Industry Standards
Roof materials have minimum slope requirements. Rise and run help determine whether the selected roof covering and underlayment approach are appropriate.
Exterior Echelon Notes
Exterior Echelon explains pitch in practical terms so homeowners understand why roof shape affects scope, materials, and cost.
