ADU builder · Whittier, CA
ADU builder in Whittier.
Design, permits, financing and construction from one local team. 600+ ADUs delivered across greater LA, including projects in and around Whittier.
Licensed & insured · Construction from $275/sq ft · 5.0★ rated
Building an ADU in Whittier
Whittier has two kinds of lots for ADUs: flatter neighborhoods, where a backyard unit or garage conversion is usually straightforward, and hillside streets where slope and fire zones come into play. The city issued about 105 ADU permits in 2023 and about 86 in 2025, per state housing reports.
ADU Resource Center designs, permits and builds ADUs in Whittier with one in-house team. Here we built a 450 sq ft, 1-bedroom backyard ADU for the owner's father, who is 89. It has a curbless shower, a bedroom door to the outside and a full mosaic kitchen backsplash, all fitted around an oddly shaped yard with avocado trees. Our nearby work includes ADUs in La Habra, Montebello, Bellflower and La Puente, and we also build in Downey.
The fixed quote comes before construction and lists what's excluded, such as third-party inspections. One project manager stays on the job through final inspection, and we can help you line up financing.
ADUs in Whittier: quick facts
Updated November 2026
- Who issues ADU permits
- City of Whittier
- Our construction rates
- $275, $300 or $325 per sq ft (basic, mid-range, luxury); garage conversions $235–$285 per sq ft
- Example cost
- A 600 sq ft one-bedroom runs about $165K–$195K in construction
- Size limits under state law
- Detached ADUs up to 1,200 sq ft on many lots; junior ADUs up to 500 sq ft inside the home
- Permit decision
- State law requires a decision within 60 days of a complete application
- Who builds it
- ADU Resource Center: design, permits and construction by one team, 600+ ADUs delivered, office in Glendale
ADU rules change. We confirm the current rules for your lot on the free consultation.
Real projects in and around Whittier
Our work in and around Whittier.
Hear it from our clients
Homeowners on building their ADU with us
More stories on our testimonials page.
Local know-how
What to know before building in Whittier.
Whittier reviews its own ADUs
Applications go to the City of Whittier's Planning Division, then through building plan check. We take care of the submittal and the corrections.
Hillside fire zones
The hills in Whittier hold thousands of homes in high and very high fire hazard severity zones. Ignition-resistant materials, and sometimes grading or retaining walls, go into the design and the quote.
Plan for inspection costs
Some projects need third-party structural observations at foundation and framing. Those fees sit outside construction, so budget for them separately. Our contracts list them as exclusions.
Designed for aging in place
Curbless showers, wide doors and a second exit help a parent stay independent. Browse our floor plans for single-story layouts that work well.
What it costs
ADU cost in Whittier
We build at a flat rate per square foot: $275 (basic), $300 (mid-range) and $325 (luxury) finishes. Here's what that means for common sizes. Construction only; design, permits and city fees are quoted separately on your consultation.
| ADU size | Basic | Mid-range | Luxury |
|---|---|---|---|
| 400 sq ft studio | ~$110K | ~$120K | ~$130K |
| 600 sq ft 1-bedroom | ~$165K | ~$180K | ~$195K |
| 800 sq ft 2-bedroom | ~$220K | ~$240K | ~$260K |
| 1,000 sq ft 2–3 bedroom | ~$275K | ~$300K | ~$325K |
Get a number for your exact size: ADU cost calculator · Browse ADU floor plans · Converting a garage? See garage conversion cost.
Free consultation
Start your Whittier ADU.
Tell us about your property. We'll confirm what's buildable, give you a real price range and walk through financing within 1 business day.
Questions
Whittier ADU questions, answered.
Still have a question? Ask us during your free consultation.
Who issues ADU permits in Whittier?
Whittier is its own city, so ADU applications go to the City of Whittier's Planning Division and then to building plan check. We prepare the application and plans, submit them and respond to every correction.
Can an ADU work for an aging parent in Whittier?
Yes. Our Whittier ADU is a 450 sq ft one-bedroom built for the owner's 89-year-old father, with a curbless shower and a second exit door from the bedroom. We plan those details in design so the unit works as needs change.
How much does an ADU cost in Whittier?
We build at a flat $275, $300 or $325 per sq ft for basic, mid-range or luxury finishes, so a 600 sq ft one-bedroom runs about $165K–$195K in construction. A 450 sq ft unit costs less, since the rate is per square foot. Hillside sites, utility upgrades and third-party inspections can affect the full project cost, and we list what's included and excluded in the fixed quote.
Is my hillside lot in a fire zone?
It might be. Whittier's hillside neighborhoods include high and very high fire hazard severity zones, with thousands of homes inside them. A lot in the very high zone needs ignition-resistant construction, and a slope can add grading or foundation work. We check your parcel before design starts.
My yard has an odd shape. Can I still build?
Usually. One Whittier owner had an irregular yard and avocado trees he didn't want to crowd, so he sketched his own layout and our team refined it into a working plan. State law allows ADUs on most single-family lots, and we fit the footprint to your yard.
Free consultation
Ready to build your ADU in Whittier?
Tell us about your property and we'll confirm what's buildable, give you a real price range and lay out financing on one free call.
