Shape Homes · Where we build · Los Altos
ADU and custom home builder in Los Altos
Los Altos caps an ADU at 1,200 square feet and then draws a diagonal line through your site that decides what you can actually build under it.
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We start with your design. Modular is how we build it, not what you settle for.
Shape Homes · Where we build · Los Altos
Los Altos caps an ADU at 1,200 square feet and then draws a diagonal line through your site that decides what you can actually build under it.
Book a consultation| Rule | What it says | Source |
|---|---|---|
| Size, one bedroom | 850 sq ft, attached or detached | LAMC 14.14 |
| Size, more than one bedroom | 1,200 sq ft | LAMC 14.14 |
| JADU | 500 sq ft | LAMC 14.14 |
| Height, detached | One story and 16 ft | LAMC 14.14 |
| Height, attached | The greater of 16 ft or the primary dwelling's limit | LAMC 14.14 |
| Setbacks | 4 ft rear and side, at least 5 ft from the primary dwelling | LAMC 14.14 |
| Daylight plane | Begins at 8 ft at the line, inward at a 6:12 slope | LAMC 14.14 |
| Privacy | Second-story windows within 15 ft of a line need a 5 ft sill | LAMC 14.14 |
| Parking | One additional uncovered space, 9 ft by 18 ft | LAMC 14.14 |
| Review | Zoning clearance letter against objective standards in Ch. 14.06 | LAMC 14.14 |
Sources: City of Los Altos ADU page, Los Altos ADU ordinance, Chapter 14.14, Los Altos Municipal Code, HCD ADU Handbook, California Energy Commission ADU guidance. Rules change often; we confirm them for your lot before design.
Size is rarely the constraint. These are.
It starts at eight feet above the property line and slopes inward at six in twelve. On a narrow Los Altos lot that plane, not the setback and not the height limit, decides your roof form and often your whole footprint. We model it before the first sketch, because a design that ignores it comes back from the counter.
One bedroom gets 850 square feet. More than one gets 1,200. But floor area above 850 counts differently, and on a constrained lot the second bedroom can cost more site area than it appears to. Worth testing both schemes on paper before choosing.
Review is a zoning clearance letter from the Community Development Director measured against the objective design standards in Chapter 14.06. There is no design hearing to win, and no discretion to appeal to. It either meets the standard or it does not, which is good news if you design to it and expensive if you do not.
A North Los Altos or Old Los Altos backyard may be flat and established; a Highlands or Country Club lot can have a more complicated grade. We compare the proposed building with the main home, outdoor seating and the route between them. The survey helps us test the daylight plane and required separations while preserving a usable garden. Bedroom count and footprint are considered together.
Mature trees often shape the best ADU position in Los Altos. We show canopies and likely root areas alongside foundations, utility trenches and construction access, then confirm whether arborist review is required. A neighboring tree can matter too. Moving a trench or delivery route at this stage can protect the landscape without compromising the interior plan or pushing the building into a less useful corner.
Los Altos offers permit-ready ADU options. We compare that route with a library plan or a design adapted to your lot. Prior review of a building design does not settle its placement, foundation, drainage, utility connections or tree impacts. We establish what can remain unchanged and what needs parcel-specific engineering before comparing the approval effort and complete cost of each option.
For a new detached ADU, energy compliance and any applicable solar requirement are part of the permit package. We check the existing electrical service, equipment locations and connection route early. The estimate also needs to account for trenching, drainage and restoration of paving or planting. A straightforward building can still have a long utility run, especially when the preferred garden location is far from the street.
A few more specifics worth knowing before you draw anything.
Most Los Altos single-family lots can add a junior ADU, up to 500 square feet, built inside the existing footprint of the main home, in addition to a full detached ADU in the backyard. That is two income or family units on one lot without touching the detached unit's size allowance. We check whether your home's existing layout can absorb a junior ADU conversion before pricing the detached build.
Los Altos publishes Permit-Ready ADU plans at 525, 854 and 1,190 square feet in three styles, and using one as drawn can shorten the plan-check cycle. The tradeoff is that no changes are allowed to the plan itself. If your lot carries a protected tree, an unusual shape, or a program the stock plan doesn't fit, foundation, drainage and utility work still need a site-specific design no matter which route you choose.
Los Altos' lots are large enough to carry a serious detached unit, and the school district and downtown keep long-term rental demand steady. In practice we see more multigenerational households using the ADU for parents or adult children than short-term renters, which changes the brief: accessible entries, a real kitchen, and a short walk to the main home matter more here than curb appeal alone.
No replacement parking is required anywhere in Los Altos when a garage or carport is converted or torn down to build an ADU. Separately, no parking at all can be required for the ADU itself within a half-mile walk of public transit. The two exemptions overlap on a lot of Los Altos parcels, and we check both during feasibility rather than assuming the standard space is needed.
If a unit on your Los Altos property was built without permits before 2020, state law bars the city from charging impact fees or penalties for it, though the city can still deny a unit that is substantially unsafe. We walk the existing structure, compare it against current code, and scope out what it would take to bring it up to a legal permit before you decide whether to legalize or rebuild.
Planning, permitting and build, in sequence.
| Step | Typical time |
|---|---|
| Planning and building permit | 10–16 weeks |
| Build, from permit | A few months; we confirm the schedule in your agreement |
| Typical city permit fees | $10,000–$16,000 |
Fees are city permit fees only; a Shape Homes construction quote is separate and fixed. Sources: City of Los Altos ADU page, HCD ADU Handbook.
Three from the library, chosen against this town's rules rather than its postcode.
Planning ranges, all in: factory package, delivery, foundation, utilities, permits and site work.
What moves a project inside its range is the lot, not the home. On Los Altos parcels the items above are what usually decide it. A range is not a bid; a fixed price applies only as written in an executed construction agreement. See the plans or how the build works.
A diagonal envelope that begins eight feet above your property line and slopes inward at 6:12. Everything you build has to fit under it. On a typical Los Altos lot it is a stronger constraint than either the height limit or the setback.
850 sq ft for a one-bedroom unit, 1,200 sq ft with more than one bedroom, attached or detached. A junior ADU is capped at 500 sq ft.
Not a hearing. The Community Development Director issues a zoning clearance letter measured against the objective design standards in Chapter 14.06. It is a checklist, not a conversation.
One additional uncovered space, nine by eighteen feet, with the standard state exemptions for conversions, proximity to transit, historic districts, permit-parking areas and car share.
The City offers permit-ready plans, but each project still needs a site-specific review. Placement, foundation engineering, utility connections, drainage and tree protection must be resolved for your property. We compare that option with the Shape Homes plan that best fits your brief.
They can. Excavation, utility trenches and construction access may enter protected root areas. We map the work around both existing and neighboring trees and confirm the arborist requirements before finalizing the foundation and service routes.
Check foundation and drainage work, utility connections, applicable solar and electrical work, permit fees, tree protection and restoration of the garden or driveway. Comparing proposals is easier when each prices the same location and the same site-work scope.
Yes. Flag lots and larger single-family parcels in Los Altos routinely support the full 1,200 square foot detached ADU. We confirm floor area and lot coverage during feasibility before committing to a bedroom count.
A new detached ADU does. Under the 2025 California Energy Code it needs new solar panels, which can be added to an existing system elsewhere on the property instead of the ADU roof. An attached ADU counts as an addition and does not need its own solar.
Only on the new building. The Santa Clara County Assessor does not reassess your existing home. It assesses the ADU at market value once it's finished, or partly on January 1 if construction is still underway.
No. Los Altos's ADU code does not allow separate sale, and the city has not adopted the state's optional condominium route under AB 1033.
Yes. State law lets the city approve both together, and the ADU is still reviewed without discretionary review. When the two are built together, utilities can treat the ADU as new residential use for connection fees, which is worth confirming before you budget the project.
We pull your parcel, the Los Altos ordinance and a street view of the driveway before the call.
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