Tearing down and rebuilding a house in Los Altos (2026): lot rules, design review, demolition permit, timeline and cost

Step 1: What the lot allows

Most Los Altos houses sit in the R1-10 single-family district. The minimum site is 10,000 sq ft (11,000 sq ft on a corner, 15,000 sq ft on a flag lot) ^[1]. Floor area is capped at 35% of a net lot up to 11,000 sq ft; larger lots get 3,850 sq ft plus 10% of the area above 11,000 sq ft ^[1]. Height is 27 ft and two stories, but two rules cut that back: a flag lot is limited to one story and 20 ft, and any lot whose coverage exceeds 30% may not have a two-story structure and drops to a 20 ft limit ^[1]. A basement does not count as a story ^[1].

Setbacks are 25 ft front, 25 ft rear, 10 ft on interior sides for the first story and 17.5 ft for the second, and 20 ft on the street side of a corner lot ^[1]. On lots 70 ft or wider a daylight plane starts 11 ft up at each side property line and rises at 25 degrees, which is what shapes the upper floor ^[1]. Run these numbers before paying for design: the difference between a one-story and a two-story answer changes the approval path in the next step.

Step 2: Design review

Los Altos tiers its single-family design review by what you are building. A new one-story house under 20 ft gets administrative review by staff. A new two-story house, or a one-story converted to two, must be approved by the Zoning Administrator at a noticed public meeting before a building permit can be issued ^[2]. That structure comes from Ordinance 2025-534, adopted in July 2025 ^[2]. The FY2026-27 fee is $3,637.50 for administrative review of work over 150 sq ft and $6,726.61 for Zoning Administrator review ^[4].

Design review and the demolition permit run on separate tracks, but Planning signs off on both: every demolition, every tree protection plan and every tree removal needs Planning Division approval ^[5].

Step 3: Protected trees

Any tree 12 in. or more in diameter measured 48 in. above grade is protected, as is any native species at 10 in., any heritage tree, and any tree a previous approval required to be kept ^[3]. Removing one needs a permit; the FY2026-27 fee is $314.57 for the first tree ^[4]. Approved removals are generally replaced one for one with at least a 24-inch box tree ^[3]. The demolition application itself must include plans and photos showing tree protection already in place ^[5], so the arborist work comes before the wrecking crew, not after.

Step 4: The demolition permit

A demolition permit is required wherever any building, structure or pool is to be taken down, and it must be finaled before the building permit for the new house can be issued ^[5]. The city’s checklist is specific. Gas and electric service must be terminated at the main, confirmed by a disconnect letter from the utility; water service to the structure is disconnected (the property’s service line may stay); the sewer line is capped with an approved fitting and inspected by Engineering; and a BAAQMD “J number” letter is obtained for the air district ^[5]. Single-family demolitions are exempt from the PCB screening that applies to larger buildings ^[5].

• Residential demolition application, plus a demolition site plan and a construction best-management-practices sheet ^[5]
• Plans and photos of tree protection in place; two copies of a site plan showing every structure and tree to be removed, for Planning approval ^[5]
• Utility disconnect letter (gas and electric), water disconnect, sewer cap inspected by Engineering, BAAQMD J number letter ^[5]
• All demolition material goes to a city-approved recycling facility; weight tickets are submitted before the demolition final ^[5]
• Submit the complete package to bldpermit@losaltosca.gov and allow 48 to 72 hours for processing ^[5]

Step 5: Building permit and plan check

Los Altos takes building permit submittals by email only and does not accept paper plans ^[7]. The city says a submittal is processed within 2 to 4 business days; that is the intake check, not the full review, and plan review does not begin until the plan check fees are paid in full ^[6],[7]. Fees are tiered by project valuation, and for FY2026-27 the valuation of any residential or commercial construction is set at no less than $591.39 per sq ft ^[4]. A 4,000 sq ft house is therefore valued at about $2.37 million for fee purposes, whatever your contract says. Once issued, a permit expires if work has not started or had a signed inspection within 365 days ^[7].

Step 6: Construction hours and neighbors

In single-family zones, construction tools and equipment may not run on weekdays before 7:00 a.m. or after 5:30 p.m., on Saturdays before 9:00 a.m. or after 3:00 p.m., or at any time on Sundays and city-observed holidays ^[8]. The same hours cover deliveries, worker arrival, start-up and shut-down on the site ^[8]. A rebuild in a built-out neighborhood lives or dies on this: the crew that shows up at 6:30 is the one the neighbors report.

Timeline at a glance

What it costs: public ranges

No city publishes construction costs, and no builder we could find publishes Los Altos-specific numbers, so the figures below are what firms publish for neighboring Palo Alto and Menlo Park. Lot sizes, hillside sites and finish levels move the price more than the city line does. Treat them as ranges, not a quote.

Rules and fees change every July with the city’s fee schedule and whenever the council amends the zoning code. Check the linked documents before relying on any figure here.