What to measure on a roof, and what each number is for

Every number on a roofing measurement report exists because something downstream needs it. Here is what each one is, and which line on the estimate it drives.

The three that get missed

Rakes and eaves are not the same edge. Both take drip edge, so they add together for that line — but only eaves take gutters, and only eaves take the first course of ice and water. Lump them together and you'll over-order one and under-order the other.

Ridges and hips both take cap, so for that line they add up. But only ridges take ridge vent. Same trap, opposite direction.

Pitch changes the price, not the quantity. A 12/12 roof has the same squares as an 8/12 of the same footprint, but it is slower, needs staging, and is more dangerous. That belongs in the labor rate, not in a fudged square count.

Waste isn't one number

A simple gable roof runs around 10%. Cut-up roofs with lots of valleys and hips run 15% or more, because every valley means cutting shingles at an angle and binning the offcut. Straight runs of drip edge and pipe boots waste nothing.

That is why waste is set per line on the package rather than once per job — see how packages work.

Measured from a report or from the roof

A measurement report from an aerial provider gives you these numbers without getting on a ladder, and you can attach the original PDF to the job so the crew and the office are looking at the same document. Measuring by hand gives you the same fields — the estimate doesn't care where the numbers came from, only that they're right.

Either way, enter them once. Everything after that is arithmetic, and arithmetic is what software is for.