With 40% pre-1930 in Berkeley, many properties have room for an ADU alongside the original structure. Brown Shingle cedar siding deterioration and moss growth on north faces often make ADU construction the ideal time to address deferred maintenance on the primary residence.
Now Booking Fall 2026: Schedule Your Consultation
ADU Builder in Berkeley
500+ projects
Since 2018
Limited Lifetime
Select Product Warranties
Get a FREE ADU Consultation
We'll contact you in 3-5 minutes to discuss your ADU project.
Your information is private and secure
For local cost factors and planning, read our ADU construction cost guide for Berkeley.
For detailed ADU pricing factors, use our 2026 Bay Area ADU cost guide.
Your next step
Start Your ADU Consultation Online
Share your property and project goals. Our team will discuss feasibility, design, permits, and the next planning step.
ADU certifications, brands, and contractor credentials
Customer-Service Obsessed
Responsive from consultation through project closeout
Architect and general contractor
One accountable team
Licensed, bonded, and insured
Verified business credentials
ADU Services 
Start With the ADU Service Your Property Needs
Detached ADUs
A new backyard structure planned around the lot, setbacks, access, utilities, fire requirements, privacy, permits, and construction logistics.
ADU Design
Architect-led feasibility and plans shaped by the property, existing home, program, code constraints, utilities, and budget.
ADU Permits
Plan-check coordination for architecture, engineering, energy documents, utility requirements, agency comments, revisions, and inspections.
Garage Conversion ADUs
Conversion planning for the existing slab, framing, ceiling height, fire separation, insulation, utilities, windows, access, and permits.
Berkeley's housing stock spans 40% pre-1930, 20% 1930-1950, 20% 1950-1975. Architectural styles range from Brown Shingle style homes (1890s-1910s) in North Berkeley Hills and Elmwood to 1920s Stucco Tudor and Mediterranean Revival in Thousand Oaks. Each era and style presents different adu requirements — from material compatibility to structural considerations. Our crews know what to expect before they arrive on site.
Berkeley's ADU permitting process reflects the city's commitment to housing production under its Housing Action Plan. The Planning and Development Department has a dedicated ADU webpage with application checklists, approved plan sets, and fee schedules. Berkeley requires a zoning verification letter before ADU plan submission, which adds a step but clarifies site-specific requirements early. Hamilton Exteriors handles the full permitting process, including the zoning verification, design review, and building permit phases.
Berkeley's housing stock is predominantly pre-war, with Craftsman bungalows, brown shingle homes, and Tudor cottages built between 1900 and 1940. Lots in the flatlands neighborhoods of South Berkeley, Lorin, and West Berkeley range from 3,500 to 5,500 square feet, requiring compact ADU designs of 400 to 600 square feet. North Berkeley, Thousand Oaks, and Claremont feature larger lots of 5,000 to 9,000 square feet that accommodate full-sized detached units. The Berkeley Hills have the largest lots, often exceeding 10,000 square feet, but steep terrain requires specialized foundation engineering.
Berkeley's proximity to UC Berkeley drives exceptional rental demand for ADUs. Graduate students, postdoctoral researchers, and university staff represent a reliable tenant pool that values walkable neighborhoods near campus. One-bedroom ADUs in North Berkeley and Elmwood command $2,200 to $2,800 per month, while units in South Berkeley and West Berkeley rent for $1,800 to $2,400. At current rates, annual gross rental income from a Berkeley ADU ranges from $22,000 to $34,000.
Berkeley offers specific ADU-supportive policies beyond state mandates. The city reduced ADU permit fees, waived certain impact fees for units under 750 square feet, and allows reduced parking requirements for ADUs near transit. Berkeley's Measure O housing bond also funds infrastructure improvements that support increased housing density. Hamilton Exteriors stays current on all Berkeley-specific policies and incentives to minimize client costs and streamline the approval process.
Neighborhoods We Serve
ADU Across Berkeley Neighborhoods
Local planning starts with the site, neighborhood context, access, and applicable city review.
Westbrae
Westbrae homeowners frequently choose Hamilton Exteriors for adu. With 40% pre-1930 in Berkeley, many properties have room for an ADU alongside the original structure. With Berkeley's West Berkeley: heavy fog, 60-68°F summers, material selection in Westbrae requires local expertise.
Berkeley Hills
In Berkeley Hills, homes are predominantly 1920s Stucco Tudor and Mediterranean Revival in Thousand Oaks. Brown Shingle cedar siding deterioration and moss growth on north faces often make ADU construction the ideal time to address deferred maintenance on the primary residence. Our crews are familiar with Berkeley Hills's architectural character and building requirements.
North Berkeley
North Berkeley features Craftsman and brown shingle homes on 5,000 to 8,000 square foot lots along streets like Shattuck Avenue and Hopkins. The neighborhood's walkability to the Gourmet Ghetto, North Berkeley BART, and Tilden Park makes ADUs highly desirable. Detached backyard ADUs of 500 to 800 square feet fit well on the typical lot configurations here.
Elmwood
Elmwood's charming commercial district along College Avenue and its 1920s residential architecture create a village atmosphere. Homes sit on 4,500 to 6,500 square foot lots with mature gardens. ADU design in Elmwood requires sensitivity to the neighborhood's architectural character, incorporating Craftsman or shingle-style details that complement existing homes.
Claremont
Claremont's grand homes on 6,000 to 12,000 square foot lots near the Claremont Hotel offer generous space for ADU construction. The neighborhood's hilly terrain provides natural separation between primary homes and ADUs, with many properties offering separate lower-level access points. ADU rents here reach $2,500 to $3,200 monthly, reflecting the premium location.
Thousand Oaks
Thousand Oaks sits between the flatlands and hills, with 1920s to 1940s homes on 5,500 to 7,500 square foot lots. The neighborhood's established oak canopy and quiet streets make it a sought-after residential area. The moderate lot sizes and relatively flat terrain make ADU construction efficient, with backyard units of 600 to 900 square feet being the most common configuration.
West Berkeley
West Berkeley's industrial-to-residential transition has created a dynamic neighborhood with 1920s worker cottages on 3,500 to 5,500 square foot lots. The area's proximity to Fourth Street shopping, the waterfront, and multiple bus lines supports strong rental demand. Compact ADUs and garage conversions are the practical choice here, making the most of tighter lot constraints.
Cragmont
Cragmont perches at the top of the Berkeley Hills with sweeping views from Cragmont Rock Park. Lots range from 6,000 to 12,000 square feet on steep terrain. The neighborhood's established gardens and architectural homes from the 1920s to 1960s require ADU designs that respect the existing landscape. Walk-out lower-level ADUs work especially well on Cragmont's sloped sites.
Project Management How Hamilton Exteriors
How Hamilton Exteriors
Manages Your ADU Project
Property Feasibility
We review the lot, setbacks, existing structures, access, utilities, drainage, fire requirements, and likely permit path.
Design and Permit Coordination
Our team coordinates architecture, engineering, energy documents, utility requirements, submittals, comments, revisions, and approved construction documents.
ADU Construction
We manage site work, foundation, framing, building envelope, mechanical, electrical, plumbing, finishes, inspections, and documented changes.
Final Inspection and Closeout
We coordinate corrections and final inspections, complete the punch list, and organize closeout and applicable warranty information.
Google rating 4.6 ★ from 47 public reviews
ADU Project Reviews
Verified public reviews from homeowners who hired Hamilton Exteriors.
Y
Yaku Escobar
via Google
We worked with Hamilton Exteriors to build a small ADU in our backyard. from the beginning the process felt organized and clear. Alex Lee was very responsive and always kept us in the loop, especially during planning and inspections. The crew was consistent and respectful of the space which we appreciated since we were living there during the build. overall everything moved pretty smoothly and the final result looks exactly like what we had in mind. really happy with how it turned out.
R
Rafa Simons
via Google
My family hired Hamilton after seeing the neigbours new ADU, the whole team were super organized and tecnological and also very patient to undestand my needs before starting the construction. But what i like the best is that they are really preocupated with the final result and they kept us well inform with details and everything. Definitely recomend them.
H
H.T.
via Google
I had a great experience working with Hamilton exteriors. From start to finish, their team was professional, responsive, and detail-oriented. They made the entire process smooth and stress-free, keeping me updated every step of the way. The quality of their work really stands out. Everything was done efficiently and exceeded my expectations. If you’re looking for a reliable company that takes pride in what they do, I highly recommend them!
J
Jessica W.
via BBB
The team was professional, communicative, and completed the job in a timely manner. They kept me informed throughout the entire process and arrived as scheduled. The work was well supervised, and the crew paid close attention to every detail. They left the property clean and organized when the job was finished. Overall, the entire experience was smooth, stress-free, and exceeded my expectations. I would definitely recommend their services to others.
Google rating: 4.6/5 from 47 public reviews
Read reviews on Google Premium Market
ADU Costs in Berkeley
$210,000–$450,000
Median home value in Berkeley: $1,400,000
Prices reflect Berkeley's premium market and Alameda County labor rates. Actual costs depend on home size, materials, and project complexity. We provide free, itemized estimates with no hidden fees.
Get Your EstimateCompare Broad ADU Project Paths
Swipe to compare all options.
| Feature | Detached ADU | Garage Conversion | Junior ADU |
|---|---|---|---|
| Location | Separate backyard structure | Within an existing garage | Within the primary home |
| Existing shell | New foundation and structure | Existing shell requires verification | Existing conditioned structure |
| Main feasibility focus | Lot, access, setbacks, and utilities | Structure, slab, height, and utilities | Interior layout and required shared systems |
| Privacy planning | Separate building and entrance | Entrance and yard relationship | Connection to the primary home |
| Dedicated guide | Detached ADUs | Garage conversions | Start with an ADU consultation |
ADU Financing
Plan Your ADU Project With Approved Credit
Financing may be available for eligible ADU construction projects with approved credit. During feasibility and scope planning, we explain current lender programs, terms, amounts, and payment timing that may apply to the design and construction path.
Ask which current options fit your ADU project scope.
Call Now (650) 977-3351 Frequently Asked Questions
Didn't find the answer to your question? Call Now (650) 977-3351
What areas do you serve?
We serve Northern California across three regions: the San Francisco Bay Area, Greater Sacramento, and the Central Valley. Our published guides cover 14 counties and 88 cities. Our Castro Valley and Sacramento offices support local estimating, permit coordination, and project planning across these regions.
How does billing and financing work?
Financing may be available for eligible projects with approved credit. Available terms depend on lender approval, project scope, and current programs. Your project manager can review the options that apply before work begins. We also accept checks, ACH, and major credit cards.
Are you licensed and insured?
Yes. Hamilton Exteriors holds CSLB License #1078806, active general liability coverage, and the required contractor bond. We also hold GAF Master Elite and James Hardie Elite Preferred credentials. We can provide current proof of coverage before work begins.
Do I need a permit for my exterior project?
Permit requirements depend on the project scope and local jurisdiction. Hamilton Exteriors coordinates required applications, plan documents, corrections, and inspections. Permit fees and allowances appear in the proposal before construction begins.
How much does a 500 sq ft ADU cost in Berkeley?
A 500 square foot detached ADU in Berkeley typically costs $150,000 to $225,000, including design, permits, and construction (Hamilton Exteriors 2024-2026 project data). At $250 to $400 per square foot, the total depends on your site conditions, finish level, and utility connection distances. Garage conversions of similar size run $150,000 to $175,000.
How long does it take to build an ADU in Berkeley?
Plan for 9 to 15 months from signed contract to move-in. Design and engineering take 2 to 4 months. Plan check in Berkeley runs 8 to 12 weeks. Construction takes 4 to 7 months for detached ADUs and 10 to 14 weeks for garage conversions.
Do I need a permit for an ADU in Berkeley?
Yes. All ADUs in Berkeley require a building permit. California state law has streamlined the process, but you still need approved plans and inspections. Building without permits creates code violations, insurance gaps, and complications when you sell. Permitted ADUs add verified value to your property.
Can I build an ADU on my Berkeley property?
If you own a single-family home in Berkeley, you almost certainly can. State law overrides most local zoning restrictions that previously blocked ADUs. Your lot must meet setback requirements, and the ADU cannot exceed certain size limits. A site feasibility review confirms what is possible on your specific property.
What is the cheapest type of ADU to build in Berkeley?
A Junior ADU (JADU) is the most affordable option at $150,000 and up (Hamilton Exteriors 2024-2026 project data). JADUs are created within your existing home footprint, so there is no new foundation, roof, or exterior walls. The next most affordable is a garage conversion at $150,000 to $200,000.
Your Next Step
Plan Your Project With a Clear Scope
Financing may be available with approved credit for eligible projects.
Tell us about your project. We usually call within 3–5 minutes to schedule the next step.
← All services in Berkeley
Also serving Berkeley
Roofing in BerkeleySiding in BerkeleyWindows in BerkeleyCustom Homes in BerkeleyAdditions in BerkeleyDecks in Berkeley
ADUs in nearby cities
21634 Redwood Rd Unit F, Castro Valley, CA 94546
Serving 88 cities across the Bay Area, Greater Sacramento, and Central Valley. Explore all service areas →