Insurance

Wildfire scores from data vendors, explained

If you have been given a wildfire number for your address, it almost certainly came from a data vendor rather than from a look at your property. Here is what those numbers are and where they stop.

Who produces them

Scores such as FireLine are produced by commercial data vendors and sold to insurers and other businesses. They are modeled from geographic data, not from a visit to your home. Different vendors use different inputs and different scales, so two numbers for the same address can disagree and both be internally consistent.

What they typically measure

The common inputs describe the landscape around a location rather than the property itself: the amount and type of vegetation, the slope of the terrain, and access, meaning how a fire would travel toward the area and how a response would reach it. A number built from those inputs describes the setting your home sits in.

What they usually do not measure

Work you have done on your own parcel is generally invisible to a model of this kind. Clearing under a deck, moving a woodpile away from a wall, pruning limbs off a roof, replacing combustible fencing where it meets the house: none of it changes the terrain or the regional vegetation layer a vendor model reads from. This is the usual reason a homeowner who has done real work sees a number that has not moved.

Hazard maps are a separate thing again

CAL FIRE publishes Fire Hazard Severity Zone maps, which are a public classification of areas by hazard. A hazard zone is not a vendor number and neither is a carrier rating. Being told you are in a particular zone tells you about the area, not about the condition of your parcel.

How a Defensible Space Score is different

This assessment starts at the opposite end. It records what is actually present on your parcel, measure by measure, and computes a score from those recorded answers against a published methodology. It reports a range alongside the number, and an evidence tier that states how much of what you told us we have actually seen. It is our own reading, not a carrier score and not an inspection, and it decides nothing about any policy.

What to do with both

Treat a vendor number as information about your setting and your assessment as documentation of your property. Under California regulation 10 CCR 2644.9 you can ask your carrier for the property level wildfire number it holds for your address and a property specific explanation of it. If the two pictures disagree, the documented inventory of what is in place is the part you can actually put in front of someone.