ADU Builders in Los Altos Hills
Get a Free Los Altos Hills ADU Site Assessment
Our Work
One Contractor From Design to Final Inspection
Axiom Renovation designs, permits and builds ADUs in Los Altos Hills, from detached backyard cottages to junior ADUs and garage conversions. You work with one licensed general contractor (CA Lic. #1105006), based in nearby San Jose, from the first site visit through the final inspection.
Los Altos Hills lots are large but often sloped, with long driveways and septic or sewer questions to settle early. Every project starts with a site assessment. We check setbacks, grading, utilities and electrical capacity, and tell you which type of ADU fits your property before you commit.
Tell us about your property and what you want the ADU for, whether that is rental income, a home for family or a home office, and we will schedule a site visit.
What we offer
Types of ADUs We Build
Every lot is different. We build each type of ADU that California allows, and we will tell you plainly which one makes sense for your property and how you plan to use the space.
Beyond the four types below, we also build two-story ADUs and ADUs combined with a garage, which work well on lots where ground-floor area is limited. We also build new homes and ADUs together as one project.
Detached ADUs
Attached ADUs
Junior ADUs (JADUs)
Garage Conversions
Get inspired by the fresh approach to crafting a home that’s uniquely yours
Process
Our ADU Process
Step 1
Initial Consultation
We begin with a thorough initial consultation to understand your needs, assess your space, and discuss your vision, budget, and timeline.
Step 2
Planning and Design
At Axiom Renovation, we understand that the planning and design phase of an ADU project is crucial to its success. Our dedicated project managers will work closely with you to understand your goals, design ideas and budget for the project.
Step 3
Material Selection
We guide you through selecting high-quality materials that fit your design and budget, ensuring durability and aesthetic appeal.
Step 4
Demolition and Preparation
Careful demolition and preparation work are performed to ready the space for construction, minimizing disruptions and ensuring a clean work environment.
Step 5
Construction and Installation
Our skilled craftsmen handle the construction phase, including obtaining permits, scheduling appointments, and the actual construction and installation with precision, building the new space according to the approved design.
Step 6
Electrical and Plumbing Work
Licensed professionals conduct all electrical and plumbing work, ensuring everything is up to code and seamlessly integrated into the new ADU.
Step 7
Painting and Finishing
We pay close attention to detail during the painting and finishing stage, ensuring all surfaces are properly prepared and beautifully finished.
Step 8
Fixture and Appliance Installation
We expertly install all fixtures and appliances, ensuring they function correctly and fit perfectly with the overall design.
Step 9
Final Touches and Clean-Up
Final touches are added, and a thorough clean-up is performed, leaving your new space pristine and ready for use.
Step 10
Final Walkthrough and Client Satisfaction
We conduct a final walkthrough with you to ensure every detail meets your expectations and address any remaining concerns, ensuring your complete satisfaction.
About Us
Why Los Altos Hills Homeowners Choose Axiom for Their ADU
Axiom Renovation is a licensed California general contractor (CA Lic. #1105006) based in San Jose. Our team builds ADUs, additions and new homes across the Bay Area. One team handles design coordination, permits, utility work and construction, so you have a single point of contact for the whole project.
ADUs often need more than framing and finishes. Many need an electrical service or panel upgrade, new sewer and water lines, or coordination with PG&E. We plan for that work from the start so it does not surprise you halfway through the build.
Our History
Quality of Materials and Workmanship
At Axiom Renovation, we believe that using the highest quality materials and employing skilled and experienced craftsmen is essential to delivering exceptional results. Our team of room addition contractors has a deep understanding of the latest materials and construction techniques, and we use only the best products to ensure that your ADU is both beautiful and durable. Our commitment to quality workmanship means that you can trust our ADU construction team to deliver a finished product in a timely manner that will exceed your expectations and stand the test of time.Â
Communication and Coordination with Project Manager
At Axiom Renovation, we understand that clear and open communication is key to the success of any construction project. Our dedicated project manager will keep you informed and involved throughout the entire construction process, ensuring that your vision for your new space is realized. We work closely with all parties involved in the project, including subcontractors, suppliers, and inspectors, to ensure that everyone is on the same page and that the project is completed on time and within budget. With our commitment to communication and coordination, you can be confident that your ADU will be a success.
Clear, Itemized Proposals
Every lot and every ADU is different, so we do not publish one-size-fits-all prices. After the site assessment you receive a written, itemized proposal that shows what is included, what is an allowance, and how payments are scheduled by construction stage.
Current ADU Project: 1,200 sq ft Detached ADU in Los Altos
A 1,200 square foot detached ADU now under construction in Los Altos, permitted through the City of Los Altos. Along with the ADU itself, the scope includes a 200-amp underground electrical service upgrade, with the ADU fed from the main house panel instead of a separate meter, coordinated with PG&E.
See more of our work in our project portfolio.
Los Altos Hills ADU Rules at a Glance (2026)
- Units allowed now: one ADU and/or one JADU on any R-A property with an existing single-family home, regardless of lot size.
- Size: an ADU of up to 800 sq ft; up to 850 sq ft (studio or one bedroom) or 1,000 sq ft (two bedrooms) if your Maximum Development Area (MDA) and Maximum Floor Area (MFA) allow; up to 1,200 sq ft with one on-site parking space and 30 ft side and rear setbacks.
- MDA and MFA: a new ADU of up to 800 sq ft is exempt from both. Area above 800 sq ft counts toward them.
- Height: 16 ft, or 19 ft with an on-site parking space and 30 ft side and rear setbacks.
- Setbacks: 40 ft front; 4 ft side and rear.
- Parking: one on-site space (tandem or in a setback is allowed), with exemptions near transit and for conversions. The ADU must use the existing driveway.
- Where an ADU cannot go: inside a Heritage Oak’s critical root zone, on slopes over 30%, within 25 ft of the top of a creek bank, in a recorded easement, or in a geotechnical or seismic hazard zone.
- Design: exterior materials, windows and roof to match the main house; wall colors with a light reflectivity value of 50 or less and roofs of 40 or less; shielded, downward-facing lighting.
- Process: ministerial, with no Site Development Review. It starts with a pre-application meeting with a Town planner, then a building permit application. Planning: 650-941-7222.
State review of the Town’s ADU rules
In a January 26, 2026 letter, the California Department of Housing and Community Development (HCD) found that parts of the Town’s ADU and SB 9 code do not comply with state law. The issues included the 16 ft height limit for detached ADUs, which must include the state’s 18 and 20 ft exceptions; requiring sprinklers in the existing house when an ADU is added; and the 650 sq ft JADU option. Where the Town’s code is stricter than state law, state law applies. We check the Town’s current code for every project.
Two Detached ADUs from January 1, 2027 (AB 956)
AB 956 raises the number of detached ADUs the Town must approve on a single-family lot from one to two. The Town may limit each to 800 sq ft of living space and apply height limits, and side and rear setbacks can be no more than 4 ft. If two detached ADUs are built, the Town does not have to also approve a JADU. How the Town applies its MDA and MFA exemption to a second ADU will depend on its ordinance update.
- Placement: we map slopes, oak root zones, creek setbacks and easements first, since they decide where two units can sit.
- Driveway and parking: ADUs use the existing driveway, so access and parking for two units have to work from it.
- Sewer or septic: properties near a public sewer must connect, and septic properties need County review. We confirm which applies early.
- Fire safety: parts of the Town are in mapped fire hazard severity zones. Fire access and wildfire-resistant construction shape the design.
- Electrical: two units usually need a load calculation and often a service upgrade. We coordinate PG&E work from the start.
Read our full guide: Two Detached ADUs in Los Altos Hills, the neighboring Los Altos guide, or the AB 956 overview.
ADU Builders Near Los Altos Hills
We also build ADUs in nearby Los Altos, Palo Alto, Mountain View and Los Altos Hills. See all of our Bay Area ADU services.
ADU Questions We Hear Most
Do I need a permit to build an ADU?
Yes. Every ADU needs a building permit from your city or county. Under California law, the city must act on a complete ADU permit application within 60 days, and we prepare and submit the application for you.
How long does it take to build an ADU?
It depends on the type of ADU, the design and how long your city takes to review plans. We give you a written schedule with your proposal so you know what to expect at each stage.
Will I need an electrical panel or service upgrade?
Often, yes. A new ADU adds kitchen, heating and cooling loads, and many existing homes do not have the capacity. We run a load calculation during the site assessment and include any upgrade in the plan.
Can I rent out my ADU?
In most cases, yes. California law allows ADUs to be rented, though cities can require rentals to be longer than 30 days. We can walk you through your city's rules.
Can you build a new home and an ADU together?
Yes. We build new homes and ADUs as a single project, which lets us plan utilities, the driveway and site work once for both buildings.