Arlington Heights, IL Environmental Rules: Flood Elevation Requirements (2026)

Section 15-102 defines the Flood Protection Elevation (FPE) as 'the elevation of the base flood or 100-year frequency floods plus one foot of freeboard at any given location in the SFHA,' making the FPE the working construction standard rather than the raw FEMA Base Flood Elevation (BFE). 00 or 70 square feet is made, a substantial improvement raises floor area more than 20 percent or equals 50 percent of market value, or a substantially damaged building is repaired. A building on permanent fill must have its lowest floor, including the basement, at or above the FPE, with fill extending at least ten feet beyond the foundation before sloping down.

An elevated building on stilts, piers, or crawl space must keep the lowest floor, all mechanical, electrical, heating, and air conditioning equipment, and utility meters at or above the FPE, with any enclosed area below the FPE limited to parking, building access, or storage and never converted to habitable space. Non-residential buildings may instead be dry floodproofed below the FPE if a registered engineer or architect certifies the structure and utilities are watertight to the base flood. New critical facilities, such as fire and police stations, schools, and hospitals, must be elevated or floodproofed to the 500-year flood elevation or three feet above the 100-year elevation, whichever is greater (Section 15-109(c)(6)).

Manufactured homes must have their lowest floor at or above the FPE, or, in an existing manufactured home park, at least 36 inches above grade on reinforced piers.