Land records · Parcel maps · October 5, 2026
What Is Lot Coverage? Zoning Limits Explained
Lot coverage is the share of a lot covered by buildings or impervious surfaces, capped by zoning. How it is calculated, what counts, and why it matters.
What is lot coverage? Lot coverage is the percentage of a lot’s area covered by buildings, and in some codes by all impervious surfaces such as driveways and patios. Zoning codes cap it to control density, preserve open space, and limit stormwater runoff. For example, a 40 percent building coverage limit on a 10,000 square foot lot allows up to 4,000 square feet of building footprint. This page is general land-records background, not legal advice.
How lot coverage is calculated
- Find the lot area from the plat, survey, or assessor record. See how to find acreage of property.
- Add up the covered area as the code defines it, such as footprints of the house, garage, and sheds.
- Divide covered area by lot area and multiply by 100.
Example: a 2,000 square foot house footprint plus a 400 square foot garage on an 8,000 square foot lot is 2,400 ÷ 8,000 = 30 percent coverage.
Building coverage vs impervious coverage
| Measure | What counts |
|---|---|
| Building coverage | Roofed structures, sometimes including covered porches |
| Impervious surface coverage | Buildings plus driveways, patios, walks, pools in some codes |
Codes differ on whether decks, eaves, pools, gravel, and pavers count. Some give credit for permeable pavers.
Lot coverage vs floor area ratio
Lot coverage limits the footprint. Floor area ratio limits total floor space across all stories. A two-story house can have modest coverage but a higher FAR.
Why it matters
- Additions: a new room or garage can push you over the limit.
- ADUs: detached units add coverage. See can I build an ADU on my lot.
- Pools and patios: may count under impervious limits.
- Stormwater: exceeding limits may trigger drainage requirements.
Where to find the limit
Look in the zoning district’s dimensional standards. See what does R1 zoning mean. Some subdivision covenants and shoreland rules set separate limits.
Coverage, setbacks, and buildable area
Setbacks often limit where you can build before coverage does. Check both. See how to find building setbacks.
If you exceed lot coverage
Options include reducing paved areas, using permeable materials if credited, redesigning, or applying for a variance.
Measuring tips
Use a survey or site plan showing building footprints rather than estimating from aerial photos. Measure at the exterior walls, and check how the code treats roof overhangs beyond a certain width. Keep a simple table of each structure and paved area so future projects can be checked quickly against the limit.
Shoreland and special areas
Lakefront and riverfront lots often face stricter impervious surface limits than the base zone, because runoff carries sediment and nutrients into the water. Some shoreland ordinances cap impervious coverage at relatively low percentages and require mitigation, such as rain gardens or buffers, for anything above.
Bottom line
Lot coverage is the percentage of a lot covered by buildings or impervious surfaces, capped by zoning. Calculate it by dividing covered area by lot area, check what your code counts, and consider it before adding rooms, garages, ADUs, or patios. Look up lot size on the Platbookmapper map.
What is lot coverage FAQ
What is lot coverage?
The percentage of a lot covered by buildings or impervious surfaces.
Does a driveway count toward lot coverage?
In codes that regulate impervious coverage, often yes.
What is a typical lot coverage limit?
Many residential zones fall roughly between 25 and 50 percent, but limits vary.
Is lot coverage the same as floor area ratio?
No. Coverage limits footprint; FAR limits total floor area.
Do decks count toward lot coverage?
It depends on the code and deck height.