How much does a home addition cost in Los Angeles?

First-story additions in LA typically run $400–$700/sqft installed. Second-story additions run $550–$900/sqft — they cost more because of the structural work to the floor below.

Can I add a second story to my LA house?

Usually yes, but the existing foundation and first-story framing have to support the load — we engineer the structural retrofit. Hillside Ordinance and view-protection rules can limit height.

Does state ADU law apply in Ventura County?

Yes — every city in the county follows the state floor. Ministerial 60-day review, one detached ADU + one JADU per single-family lot.

Do I need a Coastal Development Permit in Ventura?

Only if the parcel is inside the Coastal Zone — generally the Ventura waterfront and Oxnard's coastal strip. Most inland parcels do not.

Ventura County Home Additions.

Adding space to an existing LA house is a different project than building from scratch — you are tying into 1920s framing, surveying the lot for setbacks, and protecting an occupied home through the build. We design additions that match the original house, hold the existing roofline, and pass LADBS structural review the first time.

Ventura County permits run cleanly under state ADU law. Each city (Oxnard, Camarillo, Thousand Oaks, Ventura) has its own building department, but all hold ministerial review at 60 days from a complete submittal. The variables are the Coastal Zone (waterfront parcels) and Very High Fire Hazard Zones along the foothills.

Ventura County cost band — 2026

$400 – $700 / sqft (first-story); $550 – $900 / sqft (second-story)

Foundation work, roof tie-in complexity, and how much of the existing house you have to touch drive the band.

Ventura County permit clock

6–10 weeks ministerial

Plan on 4–6 months for design + LADBS permit, then 5–8 months on-site for a 500–800 sqft addition.

Scope — start to keys.

Setback / FAR / hillside check before contracting
Architectural design that matches the existing house line
Structural tie-in — footings, framing, roof
Full MEP extension and panel upgrade if required
Finishes, exterior siding/stucco match, paint, landscape repair

What changes about the permit here.

State ADU law guarantees ministerial review on every single-family lot in the county.
Coastal Development Permit may be required on Ventura / Oxnard waterfront parcels.
VHFHSZ areas require Chapter 7A ignition-resistant exterior assemblies.
Thousand Oaks and Conejo Valley HOAs commonly add a parallel architectural review.

What moves the Ventura County number.

Lower labor cost than LA city — typically 8–12% below LADBS-area equivalents.
VHFHSZ Chapter 7A on Conejo Valley / Ventura backcountry parcels adds $18–35k.
Coastal Zone CDP on Ventura / Oxnard waterfront adds $15–35k in soft costs.
HOA architectural review (Thousand Oaks) is fee-light but schedule-heavy.

In short.

How much does a home addition cost in Los Angeles?: First-story additions in LA typically run $400–$700/sqft installed. Second-story additions run $550–$900/sqft — they cost more because of the structural work to the floor below.
Can I add a second story to my LA house?: Usually yes, but the existing foundation and first-story framing have to support the load — we engineer the structural retrofit. Hillside Ordinance and view-protection rules can limit height.
Do I need to move out during a home addition?: Not usually. We sequence and dust-protect so the addition tie-in is the last phase. Most of our LA clients stay in the house the whole project.
Does state ADU law apply in Ventura County?: Yes — every city in the county follows the state floor. Ministerial 60-day review, one detached ADU + one JADU per single-family lot.
Do I need a Coastal Development Permit in Ventura?: Only if the parcel is inside the Coastal Zone — generally the Ventura waterfront and Oxnard's coastal strip. Most inland parcels do not.

More we build in Ventura County.

Home Additions in nearby LA areas.

Got a Ventura County project in mind?

Send us the address and we’ll pull Ventura County zoning, setbacks, and home additions feasibility before you spend on drawings.

Start a Ventura County project →