How it works
We handle everything from design to move-in. You just tell us your vision and we build the rest.
Seamless from first call to move-in
Seamless ADU design and construction backed by transparent communication, local expertise, and licensed professionals.
1Step 01 / 05
Consultation & Site Evaluation
We start with a detailed consultation to understand your goals, budget, and property conditions. Our team reviews your site to assess feasibility, setbacks, and city regulations.
2Step 02 / 05
Design & Engineering
Our team develops detailed plans and aligns design with your budget: space-efficient layouts, structural engineering, and energy compliance handled in-house.
3Step 03 / 05
Permitting & Approvals
We prepare and submit all plans for city approval. Our permitting specialists handle every step, from revisions to coordination with city officials and the required documentation.
4Step 04 / 05
Construction
Once approved, our construction team breaks ground and handles the foundation, framing, roofing, plumbing, electrical, and finishes.
5Step 05 / 05
Interiors & Final Delivery
After construction, we coordinate final inspections and walkthroughs to ensure quality and compliance. We deliver your completed ADU move-in ready, with warranties and maintenance documentation.
Testimonials & Reviews
Real reviews from Bay Area homeowners we’ve built for.
“I am so happy to find ADU San Mateo. The crew are nice, professional, doing a great job while pay attention to details, all with a good price. Highly recommend!”
“Finished work in a timely fashion. Quick to respond.”
“Excellent service highly recommended”
“ADU San Mateo went above and beyond our expectations. They were with us every step of the project, making the experience easy and headache free. ADU San Mateo has great attention to detail and abundance of carpentry knowledge. They always answered our calls and ensured the job site was clean and safe before ending the workday. The team was very professional, clean, and respectful. We contracted ADU San Mateo to build our ADU unit and cannot be happier with the outcome. Would definitely recommend to anyone looking for cost-effective get it right the first time company. Definitely would use for our future projects.”
“Dependable, responsive, quality workmanship and dedication to getting the project completed timely and on or under budget. They treated our home as if it was their own. The outcome exceeded my expectations. Would recommend to my friends and family.”
“I would highly recommend ADU San Mateo to all my friends and family. The crew is efficient, polite and hardworking. They are easy to work with and very competitive with pricing. We would definitely recommend and hire again for future projects.”
“Such exceptional work done, I am beyond pleased with the results! Paid close attention to detail and I was always kept informed. High quality work and excellent service gave us the results we expected. I was completely impressed with their professionalism and customer service. I highly recommend this business!”
“I HIGHLY recommend Eli and his team for any home remodeling projects. They did my staircase and completely did what I have envisioned. I am a perfectionist, so I am glad I met them. They are very detailed oriented, very punctual, and there were no delays. He advised me what’s the best route, up to code, and provided recommendations tweaks on my design. I provided a 3D rough draft sketch to them, the measurements were 100% accurate. I can guarantee you that you won’t be disappointed, as I went through roughly 10 contractors and FINALLY found the right team. I am looking forward to seeing how my kitchen tiles turn out.”
“They were responsive and efficient and easy to work with.”
Frequently Asked Questions
Here are some common questions along with their answers to help clear up any confusion.
Still have a questions?
Let’s discuss your goals and find the best ADU solution for your property.
Get a free ConsultationCan I build an ADU on my property in the Bay Area?
In most cases, yes. California state law has made it significantly easier for homeowners to build ADUs, and most single-family and many multi-family properties qualify. However, local zoning rules, lot size, setbacks, utility access, and fire requirements can still impact feasibility.
At ADU San Mateo, we begin every project with a zoning and site feasibility review to confirm what’s possible on your specific property. We’ll give you clear answers upfront so you can move forward with confidence.
Do you offer custom designs or just prefab options?
We specialize in fully custom ADUs designed specifically for your property, lifestyle, and long-term goals.
While prefab solutions can work in some cases, many Bay Area lots have unique constraints, such as narrow widths, slopes, height limits, or strict neighborhood guidelines, that require a tailored architectural approach.
Our design process ensures your ADU feels intentional, efficient, and seamlessly integrated with your existing home.
What’s the cost range for a custom ADU in the Bay Area?
Custom ADUs in the Bay Area typically range from $300,000 to $450,000+, depending on size, site conditions, finishes, and structural complexity.
Factors that influence cost include:
• Sloped or challenging terrain
• Utility upgrades
• Fire sprinklers or access requirements
• High-end finishes or vaulted ceilings
• Local permitting requirements
We provide transparent budgeting early in the process so you understand the full investment before construction begins.
What makes ADU San Mateo different from other firms?
We combine architectural expertise, construction experience, and deep knowledge of Bay Area zoning laws under one roof.
What sets us apart:
• In-house design-build approach
• Extensive experience navigating high-regulation cities
• Clear communication and transparent pricing
• Space-efficient layouts designed for real living
• A streamlined, stress-free process from concept to move-in
Our mission is simple: make building your ADU clear, fast, and well-executed.
How do you maximize space on narrow or sloped lots?
Bay Area properties often come with constraints, and that’s where thoughtful design makes the difference.
We maximize space by:
• Using vertical design strategies and vaulted ceilings
• Designing smart, open layouts with minimal wasted space
• Integrating built-in storage solutions
• Strategically placing windows for light and privacy
• Engineering creative foundation solutions for sloped sites
Our goal is to make smaller footprints feel spacious, functional, and comfortable.
How soon can I start?
Most projects begin with a feasibility consultation and site evaluation. From there, the typical timeline looks like:
• Feasibility & Concept Design: 4–8 weeks
• Permit Preparation & Submittal: 8–12 weeks
• City Review & Approval: 2–6 months (depending on the city)
• Construction: 6–9 months
If you’re ready to explore your options, the best first step is scheduling a consultation so we can assess your property and outline a clear roadmap.
How do you handle permitting in high-regulation cities like Palo Alto or San Francisco?
We have extensive experience navigating complex permitting environments across the Bay Area. Cities like Palo Alto and San Francisco have detailed planning standards, design review requirements, and strict code enforcement.
Our team manages:
• Zoning and setback analysis
• Title 24 energy compliance
• Structural engineering coordination
• Fire and utility approvals
• Plan revisions and city comments
We handle communication with the city on your behalf, keeping the process organized and moving forward while minimizing delays.
Your dream ADU starts here
Free feasibility review, no-obligation consultation, response within 1 business day.