Building Permit Glossary
Impervious Area Calculation
A calculation of how much of a lot is covered by surfaces that prevent water from soaking into the ground.
Site & zoningStormwaterDecks & patios
Applies to
Patios · Driveways · Carports · Garages · Additions
Project example
A new concrete patio plus a carport roof may push a lot over its impervious-area limit even if each piece is separately small.
Also called
impervious coveragestormwater area calculation
Where this term shows up in permit work and how it affects the project
The calculation can determine whether zoning, stormwater, or engineering review is needed and whether a sales promise fits the parcel.
If this term appears in a form, plan comment, or local ordinance, start with the building permit guide, compare it against the zoning permit guide, then use the permit guide directory to find the right local path.