Research Local Zoning Requirements
Beyond setbacks, zoning codes limit how much of your lot you can cover with structures and how much total living space you can build. A 30-minute call to your planning department can save you from designing something unbuildable.
Quick Summary
Time needed
1-2 hours
Cost
$0 (free research)
Key contacts
Planning department
Understanding Zoning Limits
There are three main zoning limits that affect how much you can add to your home:
1Lot Coverage (Building Coverage)
The percentage of your lot that can be covered by structures. Typically 35-50% for residential zones. Includes the house footprint, garage, shed, and any roofed structures.
Example Calculation:
- • Lot size: 10,000 sq ft
- • Max coverage (40%): 4,000 sq ft
- • Current footprint: 2,200 sq ft (house + garage)
- • Available for addition: 1,800 sq ft
2Floor Area Ratio (FAR)
The ratio of total building floor area to lot size. A FAR of 0.5 means you can build up to half your lot size in total living space (including all floors). This is the most common limit that restricts additions.
Example Calculation:
- • Lot size: 10,000 sq ft
- • Max FAR (0.45): 4,500 sq ft total living space
- • Current home: 2,800 sq ft (both floors)
- • Available for addition: 1,700 sq ft
Important: FAR typically excludes garage, unfinished basement, and attic without headroom. Check your local definition—it varies by jurisdiction.
3Height Restrictions
Maximum building height, typically measured from average grade to the highest point (usually 28-35 feet for residential). Some areas have additional "daylight plane" or "bulk plane" restrictions near property lines.
Typical Height Limits:
- • Single-family zones: 28-35 feet (2-2.5 stories)
- • Sloped lots: Often measured differently
- • Accessory structures: Usually lower (15-18 feet)
How to Research Your Zoning
Online Research
Search "[your city] zoning code" or "[your city] municipal code Chapter 17" (zoning is often Chapter 17). Look for your zone's development standards table.
Call the Planning Department
Most planning departments will answer basic zoning questions over the phone for free. Have your address ready and ask about lot coverage, FAR, height limits, and any overlay districts that apply.
Schedule a Pre-Application Meeting
Many cities offer free or low-cost ($50-150) pre-application meetings. Bring a sketch of your proposed addition and get official feedback before spending on architectural plans.
Questions to Ask Your Planning Department
- "What zone is [your address] in?"
- "What are the setback requirements for that zone?"
- "What's the maximum lot coverage percentage?"
- "What's the maximum FAR and what's included in that calculation?"
- "What's the maximum building height?"
- "Are there any overlay districts (historic, flood, environmental)?"
- "Does a second-story addition require design review?"
Overlay Districts That Affect Additions
Some properties have additional restrictions layered on top of base zoning:
Historic Districts
Additions must match the architectural style of the original home. May require approval from a historic preservation commission. Adds 2-6 months to timeline.
Flood Zones
Ground-level additions may need to be elevated. Extra engineering required. Flood insurance implications. Check FEMA flood maps for your property.
Hillside/Geological Hazard
Strict rules about grading, retaining walls, and building near slopes. Often requires geotechnical report ($2,000-5,000).
View Preservation
In some coastal and hillside areas, neighbors have legal right to their views. Height and placement may be severely restricted.
Frequently Asked Questions
Can I exceed FAR or lot coverage limits?
Only through a variance, which requires proving "hardship" and typically has low approval rates. Some jurisdictions allow small overages (5-10%) through administrative approval. Your architect can advise based on local practice.
Does basement space count toward FAR?
It depends on your jurisdiction. Many exclude below-grade space if it meets certain criteria (no windows above grade, not habitable space). Some count finished basements. Ask your planning department for the local definition.
What if I'm already over the limits?
If your home already exceeds current limits (it was built before they existed), you're "grandfathered." However, you typically cannot add more space without bringing the entire property into compliance. This can make additions impossible or require reducing elsewhere.
Ready for the Next Step?
Now that you understand your zoning constraints, it's time to decide what type of addition makes the most sense—building up, out, or just a small bump-out.