Arlington Heights, IL Building Setbacks & Zoning: Lot Coverage Limits (2026)

5, Maximum Building Lot Coverage and Maximum Impervious Surface Coverage, splits into two distinct limits for the R-3 One Family Dwelling District. Building lot coverage, the footprint of the house and any structurally attached additions, is capped at 35 percent on lots of 6,000 square feet or larger and 40 percent on smaller lots. Separately, impervious surface coverage, which includes driveways, walkways, patios, and other hard surfaces, is capped at 55 percent of the total lot for lots of 6,600 square feet or less and 50 percent for larger lots; within that overall cap, no more than 50 percent of the front yard, plus the exterior side yard on a corner lot, may be impervious.

The code also carries a narrow relief valve for existing nonconforming lots: an owner who needs only to repair or replace "essential elements" such as a driveway, walkway, or patio may seek an administrative exception from the Director of Building, but only if the replacement matches the exact dimensions that existed when the ordinance was adopted, modifying the layout is not practical or feasible, and the exception will not harm public health, safety, or welfare. c, underscoring that lot coverage is a district-specific, not citywide, standard.