Home Additions in Lafayette, CA
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The Two Numbers That Shape a Lafayette Addition
Before we design an addition in Lafayette, we check two numbers: total square footage on the lot and building height. Stay at or under 6,000 sq ft of total structures and 17 feet of height, and a single-family addition can usually avoid a Design Review Permit. Go over either one, and the project needs design review.
In Lafayette’s single-family zones, a Design Review Permit is required when total structures on the lot exceed 6,000 sq ft, or any building is taller than 17 feet, measured from average grade at the lowest foundation wall. Minor projects are decided by the Zoning Administrator; larger ones go to the Design Review Commission. Pending design review and hillside applications need story poles or ground staking, certified by a surveyor or civil engineer and usually up at least 14 days before the hearing. Owners within 300 feet are mailed notice.
Addition Work
Hillsides, Ridgelines and Trees
- Hillside Overlay District: new or modified structures and grading in the overlay need a Hillside Development Permit. Building inside a protected ridgeline setback goes to the Planning Commission.
- Protected trees: native trees with a 12-inch trunk on developed lots need a Category II permit, decided before the building permit is issued.
- Creeks: work near a creek needs a setback determination; an exception requires a soils engineer’s certification and City Council approval.
- Landmarks: exterior changes to a designated historic landmark need a certificate of appropriateness from the City Council.
From Zoning Check to Final
- Zoning plan check with the City through idtPlans: site plan, floor plans and elevations.
- Central San review if the work affects sewer.
- Contra Costa County Fire Protection District review if applicable.
- County building plan check after the City stamps the drawings.
- County inspections and final.
3675 Mt. Diablo Blvd., Suite 210, Lafayette, CA 94549
City Hall (925) 284-1968 · Planning (925) 284-1976
Zoning plan check is submitted online through the City’s idtPlans portal. Counter time is limited and Fridays are by appointment only, so book ahead.
Lafayette contracts with the County for plan check and inspection. Submit the City-stamped plans digitally through the County ePermits Center. County offices: 30 Muir Road, Martinez · (925) 655-2700. Inspections: ePermits or (925) 646-4108.
Fire sprinklers: under the County’s rules, an addition to a home without sprinklers does not trigger them unless at least 50% of the wall length and 50% of the roof are removed or replaced within a year.
Addition or ADU?
Need separate living space? A Lafayette ADU is approved ministerially with no hearing. Compare in ADU vs. home addition.
Explore More
Other Lafayette services: ADUs · Bathrooms · Kitchens · New Homes · Lafayette overview
Same service nearby: Orinda · Moraga · Walnut Creek
See home additions and second story additions.
Lafayette Home Additions FAQ
When does an addition need design review in Lafayette?
When total structures on the lot exceed 6,000 sq ft, or any building is taller than 17 feet from average grade at the lowest foundation wall.
Will I need story poles?
Pending design review and hillside applications require story poles or ground staking, usually installed at least 14 days before the hearing.
Who issues the building permit?
Contra Costa County, after the City of Lafayette stamps the plans.
Does an addition require fire sprinklers?
Not under County rules, unless the project replaces at least half the wall length and half the roof within a year.