Do I need a permit in Los Altos, CA?
Los Altos sits at the boundary of two distinct building environments — the Bay Area flatlands with Bay Mud foundations and minimal frost concerns, and the Santa Cruz Mountains foothills with granitic soil, seasonal frost, and steeper grades. Your project's permit requirements hinge on what you're building, where on your lot it sits, and whether you're touching structural elements, electrical, or plumbing. The City of Los Altos Building Department enforces the California Building Code (Title 24), which is more restrictive than the national IBC in several ways — energy code, seismic design, water conservation, and fire hardening are all stricter here. You're allowed to act as an owner-builder on your own property (California Business & Professions Code Section 7044), but you cannot do your own electrical, plumbing, HVAC, or pool work — those require licensed contractors filing subpermits. Most routine residential projects — decks, fences, sheds, room additions, kitchen remodels — require permits. A 90-second call to the Building Department before you start planning can save you thousands in do-over costs. This guide walks you through the Los Altos permit landscape: what triggers a permit, what the local building department wants to see, typical fees and timelines, and what happens if you skip the process.
What's specific to Los Altos permits
Los Altos adopted the 2022 California Building Code with local amendments. This matters because California's Title 24 energy requirements are the nation's strictest — any new wall, window, or HVAC system gets energy-code scrutiny. If you're replacing windows, installing a heat pump, or upgrading insulation, plan-check will require cool-roof coatings, HVAC efficiency documentation, and duct-sealing certification. The state also mandates solar-ready roofs on new residential construction (Title 24 Section 150.1(c)), which can trigger unexpected design requirements even on smaller projects.
Seismic design is enforced more aggressively here than in much of the country. Los Altos sits in USGS seismic zone 4 (active fault risk). Any addition over 500 square feet, any foundation retrofit, and any cripple-wall bracing must meet the California Building Code's seismic standards — which often exceed what the national IBC requires. If your house has a cripple wall (common in older Bay Area homes), the code practically requires seismic strengthening when you pull any major permit.
The Los Altos Building Department processes permits through an online portal. Over-the-counter permits (small sheds, fences, decks under specific thresholds) can sometimes clear faster if you submit complete applications with site plans, but most residential projects require plan review and one or more inspections. Plan review averages 2–4 weeks for straightforward projects; complex additions or remodels can take 6–8 weeks. The department is responsive to pre-application meetings — a 15-minute phone call with the plan examiner before you hire an architect can clarify requirements and save rework.
Fire hardening rules affect any new construction or major renovation. Los Altos sits on the urban-wildfire boundary, and the state fire code (adopted into the California Building Code) requires ember-resistant vents, Class A roofing, 5-foot defensible space, and specific deck materials. If you're building a deck, shed, or doing a roof replacement, expect the plan examiner to verify ember resistance and material listings — standard pressure-treated lumber and vinyl decking sometimes don't meet the standard, and you'll need hardened alternatives.
Water conservation code is strict. New toilets must be dual-flush 1.28 gpf. Landscape irrigation requires smart controllers with moisture sensors. Outdoor water features need recirculation. These aren't usually blockers, but they appear in plan checks and can add cost if you weren't expecting them — a simple toilet replacement might require upgrading to a certified low-flow model, and a new landscape design will definitely need sensor-controlled irrigation.
Most common Los Altos permit projects
These five projects account for the bulk of residential permits in Los Altos. Click each to see the Los Altos-specific breakdown: what the code requires, what the Building Department will scrutinize, typical costs, and what you can do yourself versus where you need a licensed contractor.
Accessory dwelling units (ADUs)
California's ADU laws (Government Code § 66411 et seq.) have made ADUs by-right in most jurisdictions, including Los Altos. New ADU or conversion of existing space — both trigger permits and require plan review, plumbing/electrical subpermits, and foundation inspection.
Decks
Decks over 30 inches above grade require a permit. Los Altos' sloped terrain means frost depth matters in the foothills (footings must be 12–18 inches deep depending on location). Attached decks also need structural tie-down and fire-hardened materials in high-hazard zones.
Fences
Most side and rear fences under 6 feet are exempt. Front-yard fences, masonry walls over 4 feet, and pool barriers always require permits. Los Altos also enforces sight-triangle setbacks at corners — a common rejection reason.
Room additions and remodels
Any new living space, bedroom, or bathroom requires a full permit and plan review. Seismic design kicks in for projects over 500 square feet. Kitchen and bathroom remodels without structural work can sometimes qualify for expedited review if you submit complete electrical and plumbing plans.
Pools and spas
All pools and spas require permits, including barriers, pumps, and bonding. California Building Code Title 24 adds strict energy-efficiency rules — covers, timers, and low-flow jets are often mandatory. Expect 4–6 weeks for plan review and multiple inspections.
Los Altos Building Department contact
City of Los Altos Building Department
Los Altos City Hall, 1 N Santa Cruz Ave, Los Altos, CA 94022
(650) 947-2700 — ask for Building Department
Monday–Friday, 8:00 AM–5:00 PM (verify hours before visiting)
Online permit portal →
California context for Los Altos permits
California's Building Standards Code (Title 24) sets the floor for all local jurisdictions — Los Altos cannot adopt less-stringent rules, only add to them. The 2022 CBC is the current edition, with updates rolling out every three years. Title 24 Division 5 (energy standards) is the strictest in the nation — expect insulation, window, and HVAC requirements to exceed what you'd see in other states. Seismic design (Title 24 Section 1605 et seq.) is mandatory for most projects; the state's fault-line data and earthquake-hazard mapping mean footing depth, cripple-wall bracing, and lateral-load design are non-negotiable. Owner-builder licensing is allowed under B&P Code Section 7044 (you can pull permits as the owner-builder on your own house without a contractor license), but electrical, plumbing, HVAC, solar, and pool work must be done by licensed contractors. Unpermitted work in California can lead to lost homeowner's insurance, title clouds, and forced demolition — the state Department of Licenses and Boards actively investigates tips from neighbors and enforces aggressively. If you find unpermitted work on a property you're buying or already own, get legal advice before trying to remedy it; retroactive permitting is possible but complicated and expensive.
Common questions
Can I do my own electrical or plumbing work in Los Altos?
No. California Business & Professions Code Section 7058.1 prohibits owner-builders from pulling electrical permits; Section 7060 does the same for plumbing and HVAC. You can act as an owner-builder for structural framing, drywall, decking, and finish carpentry on your own home, but licensed contractors must pull and sign off on electrical, plumbing, and mechanical subpermits. This is state law, not a Los Altos-specific rule — it applies everywhere in California.
What's the difference between a permit and a plan review?
A permit is the approval to do the work; plan review is the examination of your drawings before the permit is issued. Los Altos requires plan review for most projects — you submit detailed drawings (or use the city's pre-approved deck/shed plans), the examiner checks them against code, marks up issues or approves them, and then you're issued a permit. Over-the-counter permits (small fences, simple decks on flat lots) sometimes skip formal plan review and go straight to issuance. The Building Department can tell you which path your project will follow.
How much do Los Altos permits cost?
Fees vary by project type and valuation. A fence permit typically runs $150–$300. A deck permit for a 400-square-foot deck might be $400–$800. Room additions and major remodels are usually 1–2% of the estimated project cost — a $100,000 addition could be a $1,000–$2,000 permit fee. The Building Department calculates fees once they review your application; ask for a fee estimate during the pre-application stage. Inspection fees (typically $75–$150 per inspection) are separate and due when inspectors show up.
Do I need a permit to replace my roof?
Yes, but it's usually a quick, over-the-counter permit. Roof replacement requires a permit to verify that the new roof meets current Title 24 cool-roof standards (reflectivity rating of 0.60 or higher in most cases) and that Class A fire-rated shingles or tiles are specified. You'll need a roofing contractor to pull the permit and provide material certifications. The permit itself is typically $100–$200, and inspection happens once work is complete.
What if I build without a permit?
California and Los Altos actively pursue unpermitted work. Neighbors can report violations; homeowner's insurance can deny claims related to unpermitted work; title companies will flag unpermitted structures during a sale and may refuse to insure the title; the city can issue stop-work orders and fines; and you may be forced to demolish the work. The financial and legal risk far exceeds permit costs. If you've already built something without a permit, contact the Building Department immediately about remedial permitting — it's possible but expensive and may require design changes to meet current code.
How long does the permit process take in Los Altos?
Simple projects (fences, small sheds, straightforward decks on flat lots) can get over-the-counter approval the same day or within 2–3 business days. Projects requiring plan review typically take 2–4 weeks for the first review cycle; if the examiner has comments, add another 1–2 weeks for resubmittal and re-review. Complex projects (multi-story additions, pools, ADUs) can take 6–8 weeks or longer. Inspection scheduling depends on inspector availability — routine framing inspections usually happen within a few days of your request, but final inspections can be slower during busy seasons.
Do I need a variance or conditional-use permit for an ADU in Los Altos?
Probably not. California Government Code Section 66411.7 made ADUs by-right in most jurisdictions unless specific state-law criteria are met (zoning conflicts, parking conflicts, etc.). Los Altos generally allows ADUs without discretionary approval, though a second unit or junior ADU still requires a standard building permit and plan review. Call the Building Department before you start design — they'll confirm whether your lot qualifies and what conditions (parking, setbacks, lot size) apply.
What's the frost depth in Los Altos for deck footings?
It depends on where you are. In the flat Bay Area portions (near downtown Los Altos), frost depth is minimal — most code jurisdictions use 12 inches or waive footings entirely and allow slab-on-grade footings. In the foothills (higher elevation), frost depth ranges from 12 to 18 inches, and the code may require deeper footings. The Building Department will specify the required depth for your specific address — don't guess. This is one of the common mistakes homeowners make on DIY deck projects.
Do I need a survey or site plan?
For most projects, yes — or at least a scaled sketch showing property lines, setbacks, and where the work sits relative to the house and easements. The Building Department needs to verify compliance with setback rules, building-height limits, and lot-coverage rules. A professional survey (typically $300–$800) is overkill for a small deck or fence, but a detailed site plan signed by a surveyor or architect is standard for additions and major remodels. Ask the Building Department during pre-application what level of detail they require.
Ready to move forward with your Los Altos project?
Start with a call to the City of Los Altos Building Department at (650) 947-2700 and ask for a 15-minute pre-application conversation. Describe your project, ask whether it needs a permit, and ask what drawings or documentation they want to see. Have your address, lot size, and rough project scope handy. Most conversations take 10 minutes and will save you weeks of rework later. If your project involves electrical, plumbing, or HVAC, also get contractor bids — licensed trades pull the subpermits, and you're responsible for scheduling inspections. Once you've got the green light from the Building Department, you're ready to design or hire a contractor to move forward.