Find the deal‑killer before you pay for it.

The sample lot, read live

The site-wide sample lot, 1207 W 30th St, Austin, scored by the current engine (methodology v3) at Texas weights: 89 · Likely yes. Each hazard scores 0–100 from its federal source.

The total also counts the lot’s non-hazard factors, such as utilities.

SourceScored by methodology v3·Score methodology

Weights by region

Flood, wildfire and soil are weighted into the Score, and the share depends on the state: flood counts 25% in Florida. Seismic and radon weigh nothing anywhere; they are read and shown as regional context (“Context” below).

SourceMethodology v3 weights, with Florida, California and Texas overrides

How the flood factor is set

FEMA readings are checked in order and the first one present sets the factor. The lot-scale reading comes first: when the share of the lot inside a Special Flood Hazard Area is known, a lot only partly inside lands anywhere between 30 and 95. FEMA flags A and V zones as SFHA, so they are normally scored by share or at the centroid.

By share of the lot in an SFHA: 0% reads 95, 25% reads 79, 50% reads 63, 75% reads 46, 100% reads 30.

SourceFEMA National Flood Hazard Layer·All data sources

How the wildfire factor is set

USFS Wildfire Hazard Potential, sampled at the parcel. Very high potential is a heavy hit; moderate exposure trims the factor. Non-burnable ground, such as most developed urban lots, is an answer, not missing data, and reads as low.

SourceUSDA Forest Service · Wildfire Hazard Potential·All data sources

How the soil factor is set

The soil sub-score is read from the SSURGO map unit under the lot: its drainage class sets the starting point, then 10 comes off for slopes over 8% (20 over 15%) and 8 more for hydrologic group D soils, which take in water slowly. The result is held between 20 and 95.

The survey’s other ratings feed the soil caps instead: dwelling and septic limitations, flooding frequency, and how deep the bedrock and the water table sit.

SourceUSDA NRCS · SSURGO soil survey·All data sources

Why seismic and radon are context

Seismic. The level is set by the USGS short-period spectral acceleration (Ss) at the point, in four national steps, so two lots in one metro almost always share it. The design category and peak ground acceleration from the same USGS Seismic Design Maps response ride along on the report.

Radon. EPA publishes the zone per county, so it is identical for every lot in that county. Zone 1 is a mitigation line item, not a deal-killer.

SourceUSGS Seismic Design Maps · EPA Map of Radon Zones·All data sources

Caps from these layers

The Score is the lower of the weighted average and every cap. A cap only pulls the number down, and the report names it with its source.

When the National Wetlands Inventory does not answer, the report says the wetland check was not screened. Nothing is capped, and nothing says the lot is clear.

SourceMethodology v3·Score methodology

How it holds up

Queried live, every fresh run

Sources are re-queried whenever a fresh report runs. Never scraped. Successful lookups are cached for up to 7 days, so a FEMA map revision shows up the next time the parcel is re-queried.

Missing data drops out

When a source has no data for a parcel, that factor drops out of the Score. A factor whose provenance is a regional estimate is labelled Estimated. Nothing is silently penalised.

Every finding cited

Each factor names the federal dataset it came from: FEMA NFHL, USGS, EPA, USDA SSURGO, USFS.

Repeatability

Same inputs, same number. Each methodology version is frozen once shipped, so a published score reproduces.

• 81,477 cells scored on the national map (an earlier, county-level version of the engine)
• 7 federal agencies, queried live (listed below)
• 50 states covered
• 20 seconds from address to verdict

SourceBuildability published figures·All data sources

Where each hazard comes from

SourceAll data sources

Questions