Los Altos Hills is a rural residential town by design. Lots start at roughly one acre, streets curve without sidewalks, and homes sit back behind oaks, pathways, and long private drives. The architecture skews toward contemporary estates and quiet modern ranches, where clean lines, glass, and natural materials matter more than square footage for its own sake. When a homeowner here wants an accessory dwelling unit, they are rarely looking for a generic backyard box. They want a second structure that reads as part of the estate, holds its own design language, and respects the slope, the trees, and the views that made the property worth buying.
That is the work we do. New Key Construction (New Key Construction) is a Bay Area design-build firm, and this page is about one service specifically: ADU design and construction in Los Altos Hills, handled by a single team from the first sketch to the final walkthrough.
What a Los Altos Hills ADU usually needs to be
On these large lots, an ADU is almost never wedged against a property line the way it might be on a denser suburban parcel. There is room to place it thoughtfully, and that room is the opportunity. A detached ADU here often becomes a guest house, a multigenerational suite for parents or adult children, a pool house with a real kitchen, or a private studio set apart from the main residence. Because the homes are high-end, the bar for finish is high too. The ADU has to match cabinetry quality, window systems, roof lines, and material palette so it never looks like an afterthought parked in the yard.
The terrain shapes everything. Many Los Altos Hills lots slope, and the town pays close attention to grading, drainage, and the pathways that thread through the area. A good ADU plan works with the natural grade instead of fighting it, manages where water goes, and sites the unit so it does not crowd the main house or block the long sightlines people value out here.
The local planning reality, honestly
Los Altos Hills has its own planning and building departments, and it applies town-specific standards on top of California's statewide ADU rules. The things that tend to drive design decisions here are the same things that define the town: the one-acre minimum lot pattern, floor area limits that cap how much total building a property can carry, setbacks, and the grading and pathway requirements that come with rural roads and sloped sites.
In practice that means a few things for your project. Your existing house already uses part of the allowable building footprint, so the ADU has to fit inside what is left. Where you place the unit affects grading, drainage, and how it sits relative to setbacks and easements. And design review and permitting take real time, which is exactly why getting the plan right before you file matters so much. We do not quote you specific fee figures or ordinance numbers on this page on purpose. Those are set by the Town of Los Altos Hills and Santa Clara County, they change, and you should confirm the current requirements for your parcel directly with the town. What we bring is the experience to design a unit that respects those constraints from day one instead of discovering them halfway through.
Why design-build for an ADU here
Most ADU headaches come from the handoff. You hire an architect, get drawings, then shop those drawings to builders and discover the design costs far more than you planned, or cannot actually be built on your slope without expensive changes. Then everyone points at each other.
Design-build removes that gap. With New Key, one team owns design and construction together, so the unit is being priced as it is being drawn. That gives you three things up front:
- One team for design and build. The people drawing your ADU are accountable for building it. No translation loss, no blame between firms.
- Priced options up front. You see real cost ranges tied to real design choices before you commit, so the budget conversation happens early instead of as a surprise.
- 3D renderings before permits. You see your ADU in three dimensions, sited on your actual lot, before any permit is filed. You approve how it looks and feels first, which also makes design review smoother because the intent is clear.
How a New Key ADU project runs
We start with discovery: your goals for the unit, who will use it, and a walk of the property to understand grade, trees, access, and how the ADU should relate to the main house. From there we move into design, where we develop the floor plan and the exterior so the ADU belongs to the estate. You review priced options and 3D renderings, we refine, and only then do we prepare the permit set for the town.
Once approvals are in hand, the same team builds it. Because design and construction never split apart, the unit you approved in renderings is the unit that gets built, on your slope, with your finishes, managed by people who have been on the project since the first conversation.
If you are weighing an ADU on your Los Altos Hills property, the best first step is a property walk and an honest conversation about what fits inside your lot's limits. That is where good ADUs in this town begin.
FAQ
Can I build an ADU on my Los Altos Hills property?
Most single-family lots in Los Altos Hills can accommodate an ADU, but the specifics depend on your parcel: how much of the allowable floor area your existing home already uses, your setbacks, the slope, and grading and drainage on the site. The honest answer is that it is parcel-specific. A property walk and a check of the current Town of Los Altos Hills requirements will tell you what is feasible before you invest in design.
What makes a Los Altos Hills ADU different from a standard backyard ADU?
The lots are large and often sloped, the homes are high-end contemporary estates, and the town cares about grading, pathways, and floor area limits. So the ADU is less about squeezing a unit into a tight corner and more about siting a well-finished second structure that matches the main house and works with the natural grade and views.
What does design-build mean for my ADU?
It means one team handles both the design and the construction of your ADU. You get priced options up front and 3D renderings of the unit on your lot before permits are filed, and the firm that designs it is the same firm accountable for building it. That removes the handoff gap where a separate architect's design turns out to be over budget or impractical to build.
Do you handle permits and town approvals?
Yes. We prepare the permit set and work through the Town of Los Altos Hills design review and building process. Because you have already approved priced 3D renderings, the design intent is clear going in, which helps the review move more smoothly. We do not promise specific timelines or fees, since those are set by the town and depend on your project.
When should I bring you in?
As early as possible, ideally before you have committed to a fixed design or budget. The most expensive ADU mistakes happen when a design is locked in before anyone has checked it against the lot's floor area limits, slope, and grading reality. Starting with a property walk lets us design within those constraints from the first sketch.
