Why roof quantity disputes matter
A roofing square is 100 square feet of roof surface. Because a pitched roof is longer than its footprint, the surface is the footprint multiplied by a pitch factor. At 6/12 that factor is about 1.118; at 10/12 it’s about 1.302. Leave the pitch out, or measure from an aerial photo without correcting for slope, and an estimate can come up several squares short.
Waste, steep charges and Montana roofs
- Waste: hips, valleys and dormers need more cut material. A plain gable might need 10%; a cut-up roof can need 18% or more.
- Steep and high roofs: estimating software usually adds labor for pitches of roughly 7/12 and up and for multi-story eaves.
- Snow country details: ice-and-water membrane at eaves and valleys, snow guards on metal roofs and drip edge are common items to check.
This is planning math, not a measurement report. For a hail claim, pair it with our guide to hail claims on Montana roofs. Figures are illustrative.
Questions about this tool
How do I find my roof pitch?
Count the inches the roof rises over 12 inches of horizontal run, using a level and tape from the attic or a ladder, or read it from a measurement report. Never climb a roof you aren’t equipped for.
Why does the calculator round bundles up?
Shingles are sold in whole bundles, usually three per square, so any fraction means buying another bundle.
Does this include ridge cap and starter?
Not separately. Those are linear items measured in feet. The waste factor covers cutting loss on the field shingles only.