Do I need a permit for HVAC work in
Los Altos, California?

Los Altos HVAC permits — the key details

Los Altos Building Department enforces the 2022 California Building Code Title 24, Chapter 14 (Mechanical Systems), which requires permits for nearly all HVAC work except like-kind replacements and minor service. A 'like-kind replacement' means you are removing an existing furnace, air conditioner, or heat pump and installing an identical model (same capacity, same location, same ductwork) with no changes to refrigerant charge, efficiency rating, or distribution. However, California Title 24 Part 6 updates every three years, and the current iteration (2022) requires new equipment to meet minimum SEER2 15 for air conditioning and HSPF2 8 for heat pumps in Climate Zone 3 (most of Los Altos coast). This means that even a straight replacement often violates code if the old unit was a 2015 SEER 13 model — you cannot install equivalent efficiency; the new unit must meet 2022 minimums. The result: 'like-kind' exemptions rarely apply in Los Altos for aging systems, and most homeowners end up filing a permit. Refrigerant service (top-ups, leak repair, evacuation) and minor ductwork repairs (tape, caulk, damper adjustment) are exempt from permitting, but if your contractor replaces a refrigerant line set, installs new ductwork, or changes the system configuration, a permit is required.

The Los Altos permit process is entirely online through the city's permit portal. You or your licensed HVAC contractor uploads the mechanical permit application (Form LA-101 or equivalent), a load calculation (Manual J or equivalent), and ductwork plans (if ducts are modified). The city's plan reviewers typically respond within 5–10 business days with either approval, conditional approval (minor revisions), or a request for more information. Common rejection reasons in Los Altos include missing load calculations (required for any system upgrade or new installation), ductwork plans that don't show sealing or wrap (Title 24 Part 6 mandates duct insulation R-6 in unconditioned spaces), and equipment specs that don't list SEER2/HSPF2 ratings. Once approved, you schedule the rough inspection (ductwork, refrigerant lines, supports) and final inspection (operation, filter fit, thermostat function). Most HVAC jobs pass final inspection on the first try because mechanical work is straightforward, but ductwork sealing and insulation failures are the most common deficiencies. The entire permit-to-final-inspection cycle typically takes 2–3 weeks in Los Altos.

Permit fees in Los Altos are assessed on the estimated project cost, not equipment tonnage. The city uses a tiered fee schedule: roughly 1.5–2% of project valuation, with a minimum of $150 for mechanical work. A typical furnace replacement ($4,000–$6,000 all-in) incurs a $150–$200 permit fee; a new system with ductwork ($8,000–$15,000) runs $200–$400. Plan review is included in the permit fee; inspection fees are separate (typically $75–$150 per inspection, two inspections average). Los Altos also requires a copy of the HVAC contractor's license (C-20 or C-16) and proof of workers' compensation insurance on file before permit issuance. If you hire an unlicensed or out-of-state contractor, the permit will be denied. This is a hard rule in Los Altos — the city strictly enforces California Contractors State License Board compliance. Owner-builders can pull their own permits if they are the property owner on the deed, but the HVAC work itself must be performed by a licensed contractor; you cannot do the work yourself.

Los Altos' coastal location (Climate Zone 3B–3C) has specific HVAC implications. The city is in ASHRAE Zone 3C (marine climate), which requires relatively modest cooling capacity but strict ductwork sealing because marine air is corrosive and salt spray accelerates metal fatigue. Los Altos Building Department has flagged premature refrigerant line failure in systems installed with poor ductwork sealing practices, so plan reviewers scrutinize duct work drawings for integrity. Additionally, the city is near the San Francisco Bay National Wildlife Refuge, and some properties in south Los Altos are in flood zones; if your property is in FEMA AE or VE zones, the HVAC equipment must be elevated above the base flood elevation (typically 2 feet above), which may require a mechanical permit addition and revised ductwork routing. The city's Energy Commission office (part of the Building Department) also enforces Title 24 Part 11 (Residential Commissioning) for new systems, meaning you must complete a commissioning checklist with the HVAC contractor to confirm proper refrigerant charge, airflow, and thermostat calibration. This is not a separate permit step, but it is a mandatory final-inspection requirement in Los Altos.

Before filing a permit, confirm that your HVAC contractor is licensed and insured, and request a detailed scope of work. Ask your contractor to specify whether the work is a like-kind replacement (unlikely to qualify), a system upgrade with new ductwork, or a minor repair. If there is any ambiguity, contact the Los Altos Building Department or file a pre-application question through the online portal; most staff respond within 1–2 business days. Have your contractor prepare a Manual J load calculation if equipment capacity is changing, and request a ductwork plan (even a simple sketch) showing duct layout, insulation, and sealing methods if ducts are being installed or modified. Gather the contractor's C-20 or C-16 license number and workers' comp certificate number before work begins, and ensure the contractor submits all documents to the city on your behalf. Most licensed HVAC firms are familiar with Los Altos permitting and will handle this automatically, but confirming upfront saves weeks of delay.

Three Los Altos hvac scenarios

Title 24 Part 6 efficiency standards and Los Altos enforcement — why your old system's specs don't guarantee code compliance

California's Title 24 Part 6 (Energy Standards for Residential and Nonresidential Buildings) is updated every three years, and each iteration raises minimum efficiency thresholds. The current standard (effective January 1, 2023) requires new furnaces to achieve 95% AFUE (Annual Fuel Utilization Efficiency), air conditioners to meet SEER2 15, and heat pumps to hit HSPF2 8 in Climate Zone 3 (most of Los Altos coast). Los Altos Building Department plan reviewers cross-reference every submitted equipment spec sheet against these minimums before approval. A homeowner might find a contractor willing to install a 2018-model 14 SEER AC unit (which was code-compliant in 2018) at a bargain price, but Los Altos will reject the permit because 14 SEER converts to roughly SEER2 11 under the new metric, falling 4 points below the 2023 minimum. This is not negotiable; the city will not approve the permit until equivalent-or-better SEER2 15 equipment is specified. Additionally, Title 24 Part 6 requires ductwork insulation (R-6 minimum in unconditioned spaces) and ductwork sealing for all new systems. Los Altos has increasingly strict ductwork scrutiny because of past disputes over duct leakage — the city mandates a post-installation ductwork leakage test (blower door method, max 8% leakage at 25 Pa) before final sign-off. If the initial test fails, the contractor must re-seal (tape, mastic, or fiberglass tape on seams) and retest. Budgeting for a $300–$500 ductwork sealing and test fee is standard. Plan ahead by confirming that your contractor is fluent in Title 24 Part 6; many older or out-of-state HVAC firms are not, and they submit plans that fail initial review.

Los Altos online permit portal: navigating plan submission and inspection scheduling for HVAC work

Los Altos operates an entirely digital permit system, with no over-the-counter same-day mechanical permits. The city's online portal (accessible via the city website) requires account creation, application form completion (identifying property address, applicant, contractor, and work scope), and upload of supporting documents before submission. For HVAC permits, required uploads typically include the contractor's C-20 or C-16 license copy, proof of workers' compensation insurance, the load calculation (Manual J PDF), equipment specification sheets (download from the manufacturer's website), and ductwork plans (if applicable). Many homeowners expect their contractor to handle this, but if the contractor delays or submits incomplete documents, the city's plan reviewer will issue a 'request for information' (RFI) holding the permit in queue. Response time to RFIs is 5–7 days, so a single missing spec sheet can delay approval by a week. Proactively confirm with your contractor that all documents are ready before submission. Once the permit is approved, the portal generates a permit number and authorization to proceed. Inspection scheduling is also online: the contractor or homeowner logs into the portal, selects an available inspection date (typically 2–5 business days out), and the inspector confirms within 24 hours. For HVAC, rough inspection is typically 2–3 hours (ductwork, refrigerant lines, electrical work are checked), and final inspection is 1–2 hours (operation verification, refrigerant charge, filter fit, thermostat settings). If either inspection fails (e.g., ductwork isn't sealed to code standard), the inspector issues a 'deficiencies' list, and the contractor re-inspects after corrections (usually within 5 business days). Plan on 2–3 weeks total from submission to final approval in Los Altos, longer if there are plan revisions or inspection failures.

Common questions