Difference between Gross Area and Floor Area fields

Gross Area and Floor Area are two different fields that are used in two different ways. The main difference between Gross Area and Floor Area is that Gross Area may have an impact on loss estimates while Touchstone does not currently use Floor Area in any loss calculations.

You can think of the Gross Area as “square footage”, where it represents the total square footage of the building. This value can have an impact on losses for the US Hurricane and US Earthquake models.

Effect on AIR Hurricane Model for the United States

The vulnerability modification applies only to risks coded as: General Residential (301); permanent, single-family (302); or multi-family (303) dwellings for which a building gross area above 3,000 square feet is also provided. Touchstone interprets the user-input square footage as the Gross Area of the building for both single-family (302) or multi-family (303) dwellings.

Effect on AIR Earthquake Model for the United States

The vulnerability modification applies only to risks coded as: permanent, single-family (302); or multi-family (303) dwellings for which a gross area above 3,000 square feet is also provided. Touchstone interprets the user-input square footage as the gross area of the building for both single-family (302) and multi-family (303) dwellings regardless of the input of "number of risks" and "number of stories". Therefore, for multi-family homes (occupancy class 303), the square footage is for the entire building. Refer to the "Known Issues" section in the Touchstone Release Notes, available on the Client Portal, for information about the required corrections when modeling high-value homes.

Usage notes

•       Most construction classes are supported except for 200-series construction types, manufactured homes (construction classes 191-194), and plate glass construction types (construction classes 185-187).

•       While the modification applies only to Coverage A—because coverage C and D damage is a function of coverage A—there will be indirect impact on coverage C and D losses. By contrast, Touchstone does not currently use the Floor Area value for any loss calculations; Floor Area is solely an informational field. The Floor Area represents the area of an individual floor of a building. Where the Gross Area value captures the total area of the building, the Floor Area value captures only the area of an individual floor of a building.