Roof pitch is the amount the roof rises over a 12-inch horizontal run. A 5/12 pitch rises 5 inches for every 12 inches across, while a 2/12 pitch is low slope and needs special material and waterproofing decisions.
What roof pitch means
Pitch describes slope. A 6/12 roof rises 6 inches vertically for every 12 inches horizontally. The higher the first number, the steeper the roof.
Pitch affects price because it changes roof area, crew speed, safety setup, material handling, and what roofing products can be installed.
Common pitch examples
- 2/12 pitch is about 9.5 degrees and is considered low slope for many shingle applications.
- 4/12 pitch is about 18.4 degrees and is common on many residential roofs.
- 5/12 pitch is about 22.6 degrees.
- 6/12 pitch is about 26.6 degrees.
- 12/12 pitch is 45 degrees and requires much more safety setup.
How roofers measure it
A roofer can measure pitch from the roof surface, attic framing, or roof measurement software. The basic field method uses a level and tape measure: hold the level horizontally, measure 12 inches out, then measure the vertical rise from the roof surface.
Homeowners should not climb a roof just to measure pitch. Photos, attic access, satellite measurements, and a free roof inspection are safer ways to estimate it.
Why low slope matters
Low-slope roof areas drain more slowly and need stronger waterproofing details. Some shingle products are not appropriate below specific slope limits without special underlayment.
If a porch, addition, dormer, or rear roof plane is around 2/12, ask the roofer how they are handling underlayment, flashing, and material selection.