ADU Builder Altadena.
Architect-led ADU design and permitting in Altadena. Fixed-fee design, streamlined permits, and free site evaluations.
Our completed and upcoming projects near Altadena, CA.
Information for Victims of the 2024 Altadena Fire
If your home was damanged in the 2024 Altadena Fire, a new ADU can be built on a property if a household wants to temporarily occupy it while they wait for a replacement primary dwelling unit to be built on the same property.
The new ADU will not be considered a temporary structure and will not need to be removed from the property at a future time.
LA County will require an application and permits for the new ADU, which will be expedited. The new ADU will need to comply with current Zoning Code and State law requirements.
For more information, visit LA County Recovers or contact us for assistance.
Schedule a free site visit to get started
30 minutes. We walk the property, figure out what's feasible, and answer any questions you have.
ADU Regulations in Altadena
Last updated 2026-05-27. Always verify with your local building department.
Full rules breakdown for AltadenaADU Permits in Altadena
Based on LA County Building & Safety permit records. Comparing full calendar years 2025 vs 2024.
| Year | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | 2026* |
|---|---|---|---|---|---|---|---|---|---|
| Permits | 51 | 92 | 129 | 163 | 161 | 136 | 132 | 1,073 | 325 |
| Median valuation | $80k | $82k | $80k | $110k | $93k | $120k | $125k | $235k | $470k |
* Year-to-date
Note: permit data for this area includes Eaton Fire (January 2025) rebuild applications. The spike in 2025 largely reflects disaster-recovery activity rather than organic ADU growth.
Source: LA County Building & Safety public permit records, deduplicated by case number (methodology). Explore the data →
ADU rules in Altadena, answered.
Common questions about ADU permits, setbacks, fees, and timelines in Altadena. Always verify with your local building department before submitting.
The maximum size for a detached ADU in Altadena is 1,200 sq ft.
A licensed engineer on your lot, free.
30 minutes. We walk the property, figure out what's feasible, and answer any questions you have.
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Explore all of our services.
One accountable team for every step of your ADU project — from initial sketches and city permits to financing, construction, and legalization.
ADU Design
Our ADU design team works closely with each client to create adaptable layouts that fit your site, lifestyle, and goals.
Learn more →ADU Building Permits
We manage every ADU building permit, drawing, document, and approval with your city and county — start to finish.
Learn more →Legalizing Unpermitted ADUs
We help you navigate the legalization process for your existing ADU, ensuring compliance and securing permits.
Learn more →ADU Construction
We oversee the full construction process with care, skill, and clear communication, turning your plan into a beautiful ADU.
Learn more →Prefab ADUs
Save money and build faster with a modular ADU. Factory-built, site-installed, and ready in months — not years.
Learn more →ADU Financing
We work with multiple ADU-specific lenders so you can find the right financing — HEA, HEI, HELOC, or construction-to-perm.
Learn more →