How Long Does an ADU Take in Los Altos? A 2026 Week-by-Week Timeline

A factory-built ADU in Los Altos typically takes about 5 to 9 months from first call to move-in, and Los Altos sits at the easy end of our service area’s schedule spread: lots are large and mostly flat, access is generous, and the city reviews ADUs ministerially under the state baseline, a decision within 60 days of a complete application, no hearing (Government Code sections 66310 to 66342). The one uncontrollable stays uncontrollable: permitting workload. Everything else on this page is schedulable.

The short version: Weeks 1 to 2 map your (probably spacious) envelope. Weeks 3 to 8 design and prepare plans. Weeks 8 to 20 the city reviews while your home is built in our factory. Delivery is one crane day, then hookups and the final sign-off. Big lots mostly change which model you pick, not how long it takes.

The Los Altos ADU timeline, week by week

Weeks	Phase	What happens
1 to 2	Property analysis	Free 30-minute review: envelope, utilities, placement options
2 to 4	Site visit + feasibility study	No-cost site visit; the feasibility study prices the project and plans utility runs across a larger lot
4 to 8	Design + plans	Model locked, placement optimized for privacy, Title 24
8 to 20	Permit review	60-day ministerial clock from a complete application
10 to 22	Factory build + foundation	Parallel with permitting
Final week	Delivery + finish	Crane set in one day, hookups, final inspection, keys

All in, plan on about 5 months for a smaller model and roughly 9 for the 1,200 square foot homes, compared with the 16 to 24 months a site-built ADU typically requires.

What moves the schedule in Los Altos

Utility runs, not setbacks. On a quarter-acre-plus lot the unit fits easily; the design question is how far power, water, and sewer must travel to reach it. Longer runs cost trench feet, not calendar months, but they belong in the budget on day one, which is what the feasibility study pins down.

Model deliberation. The honest Los Altos schedule risk is the pleasant one: with room for anything from our 450 square foot studio to the 1,200 square foot Twelve Hundred U, families take longer deciding. The ADU Designer by Framework First and a factory tour compress that phase; the permit rules themselves are in our Los Altos ADU permits guide.

The clock waits for a complete package. As everywhere, the 60-day protection attaches to complete applications. Our plan packages are drawn to clear review in one round.

The parallel build

While Los Altos reviews, your home is assembled about 97% complete in our Salinas factory, about 65 minutes away, and the foundation goes in simultaneously. Delivery is one crane morning; on wide Los Altos streets it is among the simplest sets we do.

The total tracks the home you order: the 660 square foot Six Sixty at $309,000, priced with a permitting budget built in, runs about 5 months best case; the 1,200 square foot Twelve Hundred at $549,000 and U-shaped Twelve Hundred U at $599,000 run 7 to 9 months, permitting willing. Larger models rent and appraise accordingly in this market; our guides on ADU appraisal value and multigenerational living cover the two most common Los Altos motivations.

Frequently asked questions

How long does a Los Altos ADU permit take?

State law requires a ministerial decision within 60 days of a complete application, with no hearing. In Los Altos the paperwork is rarely the long pole, since big flat lots make for clean submissions; the wildcard is department workload, so budget 60 to 90 days of total permitting to be safe.

Does a bigger model take longer?

Yes, mostly in the factory: the 1,200 square foot three-bedrooms run about 7 to 9 months end to end versus about 5 for mid-size models. The permit path is the same either way.

Do long utility runs delay the project?

They add trenching days and cost, not months, when planned upfront. Surprises are what cost months, and the feasibility study exists to eliminate them.

What is the fastest realistic Los Altos timeline?

About 5 months for a mid-size model with clean permitting. We schedule to protect that shape and never promise a date, because the review queue is the city’s.

Put a plan on that big lot

Envelope, utilities, and the right model are all knowable this week. Book a free property analysis and our team will map your Los Altos timeline; the half hour costs you nothing.