Costa Mesa Building Permit Guide
Everything you need to know about building permits in Costa Mesa: fees, timelines, required drawings, and the city-specific quirks that trip up most homeowners. 2026 data.
Drafted from public city data for 2026 — verify current fees and timelines with the Costa Mesa Building Division before final planning. Last updated: 2026-04-10.
City of Costa Mesa Development Services — Building Division
$2,200 – $13,000
Costa Mesa fees are among the more reasonable in coastal OC. Kitchen/bath remodels: $2,200–$4,800. Additions: $5,000–$10,000. ADUs: $5,500–$12,000 including impact fee offsets under state law.
Costa Mesa closes Fridays, so effective review weeks are 4 business days. ADUs move through the fastest of any OC city we work with because Costa Mesa adopted the streamlined state ADU rules aggressively.
Contractor's Take
“Costa Mesa is the easiest coastal OC jurisdiction we work in for ADUs. If your lot fits the criteria, the city will move you through in 60 days. The Friday closure is the one scheduling quirk to watch — submit early in the week so correction responses have full 4-day windows to be processed.”
Permit Submission Process
- 1Submit plans through the OpenCounter online portal
- 2First-round plan check runs 10–15 business days
- 3Respond to correction letters (typically 1–2 rounds)
- 4Pay fees and receive permit
- 5Schedule inspections via the portal
Common Reasons Permits Get Rejected
- •R-1 zone setback encroachment in small Westside lots
- •Older-home electrical or plumbing not brought up to current code where work occurs
- •ADU parking exemption not properly documented (even though state law allows it)
- •Eastside Costa Mesa design review standards not met
- •Roof pitch or material change not matching neighborhood character in Mesa Verde
Costa Mesa-Specific Quirks
Costa Mesa has adopted the streamlined state ADU review rules aggressively. Detached ADUs under 800 sq ft can move through in 60 days or less.
Eastside Costa Mesa has more stringent design review for exterior changes because of the cottage/bungalow character of the neighborhood.
The building department is closed on Fridays, so effective review week is only 4 days — plan accordingly.
Mesa Verde and some other tract neighborhoods have loose HOAs that may still request plan review but carry less weight than Irvine villages.
Smaller Westside lots (5000–6000 sq ft) make ADU siting tight but not impossible.
Permit Notes by Project Type
Kitchen Remodels
Straightforward unless the home is in the Eastside cottage overlay, which adds exterior design review.
Bathroom Remodels
Fast-track for simple remodels. Older homes may trigger drain line or venting upgrades.
ADUs
Costa Mesa is the OC gold standard for streamlined ADU review. Detached units under 800 sq ft clear in 60 days.
Additions
Eastside Costa Mesa additions need to match neighborhood character — expect design review. Other neighborhoods are more flexible.
Example Recent Permit
Detached 650 sq ft ADU
- Scope
- One-bedroom detached ADU, new utility connections, concrete pad
- Fees Paid
- $7,200 city (school fees offset under state law)
- Total Timeline
- 9 weeks
Frequently Asked Questions
How long does a Costa Mesa ADU permit take?
Costa Mesa has adopted the streamlined state ADU review rules. Detached ADUs under 800 sq ft typically permit in 60 days or less once plans are complete.
What days is Costa Mesa building department open?
Monday through Thursday 7:30 AM – 5:30 PM. The building department is closed on Fridays. Effective plan check review weeks are 4 business days, so plan submissions for early in the week.
Does Costa Mesa have design review for remodels?
Most neighborhoods do not require design review for standard remodels. Eastside Costa Mesa has design review for exterior changes because of the cottage/bungalow character of the area.
Tools & Related Resources
Permit Timeline Estimator
Get a realistic timeline and fee estimate for your specific project in Costa Mesa.
Interactive QuizADU Feasibility Quiz
Find out if your lot can support an ADU in under two minutes.
LocationCosta Mesa Overview
Stone Development supports Costa Mesa homeowners who need kitchen remodels, ADUs, bathrooms, and broader renovation scopes planned around real lot and neighborhood dynamics.