How accurate is a Roof Manager report?
For buildings with HIGH-quality satellite imagery — the case for nearly every urban North American address — Roof Manager measurements land within 2–5% of an on-roof tape-measure. Here's the methodology, the data sources, and what we do when the engine isn't confident.
The three data sources behind every report
1. Google Solar API — building footprint & per-segment pitch
We call Google's Solar buildingInsights endpoint for every property — the same authoritative source Google's own solar product uses. This gives us the LiDAR-calibrated 3D building model, the per-plane pitch and azimuth, and the canonical roof-segment decomposition.
2. DSM elevation rasters — per-pixel roof height
From the same Solar API dataLayers endpoint we pull GeoTIFF Digital Surface Models. Our engine parses these to extract per-pixel roof heights, which is what lets us recover the slope/length of every edge with sub-meter resolution.
3. Our own geodesic measurement engine
User-drawn GPS traces (eaves, ridges, hips, valleys) are processed through our spherical-geodesic math library — published in TypeScript with a standalone Python reference implementation — to compute projected area, sloped area, edge lengths, and material take-off at configurable waste factors.
What we cross-check before delivery
- 1Engine total vs. Solar API total. Our engine computes a roof area from your traces; the Solar API publishes its own. If they diverge beyond tolerance, the report goes to manual review — we don't silently emit a wrong number.
- 2Imagery quality score. The Solar API publishes a quality score per property: HIGH, MEDIUM, LOW, or BASE. We surface this on every report. LOW or BASE coverage triggers a warning — and we don't consume the credit.
- 3Pitch sanity bounds. Slopes outside 0°–60° for residential or 0°–15° for low-slope commercial flag the segment for human review.
Challenge any number on a report
If a measurement on a delivered report doesn't match your tape-measure, email us with the report ID. We re-run the engine, audit the imagery, and either issue a corrected report or refund the credit — same business day.
Email an accuracy challengeOr view a sample report first — no signup needed.