Lot coverage

Lot coverage limits how much of a parcel may be covered by buildings. It is expressed as a percentage of the total lot area and set by the zoning district.

What counts

Almost always the main structure's footprint. Beyond that it varies, and the variation is where projects get caught:

• Detached garages and sheds usually count
• Covered porches and carports usually count
• Roof overhangs sometimes count
• Pools and pool decks sometimes count
• Driveways and walkways usually do not count toward building coverage, though they may count toward impervious surface

Why it constrains additions

Lot coverage is the limit that most often stops a single story addition on an established lot. The house, the garage, and the covered patio together may already sit near the cap, leaving less room to expand than the empty yard suggests.

Coverage versus impervious surface

These are two different limits and both can apply to the same lot. Lot coverage is about buildings. Impervious surface is about anything water cannot pass through, which includes paving. A design can satisfy the coverage cap and fail the impervious one, particularly when a new driveway is part of the work.