Which permit
The County's How to apply for a building permit page (read 23 October 2026) sorts work into three types:
| Job | Permit type | How it works |
|---|---|---|
| Furnace, heat pump, AC or air handler replacement | Mechanical maintenance permit ("ductwork, mechanical appliances, HVAC, exhaust hoods") | Online, no plans |
| New or replaced ductwork | Mechanical maintenance permit | Online, no plans |
| New circuit or service upgrade for the equipment | Electrical maintenance permit ("circuits, outlets, service upgrades") | Online, no plans |
| Gas piping to a new appliance | Plumbing maintenance permit ("gas service/piping") | Online, no plans |
| HVAC as part of an addition or major remodel | Big-job permit with plans | The County says 6 to 8 weeks |
Maintenance permits are for jobs that replace something that already exists. A first-time heat pump in a house that never had central air is a judgment call the page does not settle; ask Building and Safety on 415-473-6550 (Monday to Thursday 8 to 4, Friday 8 to noon). The County permits only the unincorporated area; San Rafael, Novato, Mill Valley and the other cities and towns run their own departments.
How to apply
- Open the County's permit portal, where "All building permits start at the same place."
- Choose a mechanical maintenance permit (and an electrical one if circuits change) and describe the equipment.
- Pay online; the County will never ask for payment by wire, Zelle, Venmo or PayPal.
- Post the job card and keep the inspection card; inspectors sign it as each inspection passes (How permits work).
- Pass the final within the permit's life. "Your permit expires in 1 year", extended a year by each passed inspection.
What it costs
The County's Fee Explanation page (read 23 October 2026) lists the parts:
| Line | How it is calculated |
|---|---|
| Application fee + issuance fee | 77% and 23% of the Building and Safety service fee |
| Planning surcharge | 10% of those two fees |
| Technology enhancement fee | 6% of those two fees |
| Seismic (SMIP) tax | 0.01% of job value, residential |
| Building Standards "green" tax | 0.004% of job value |
| Roads impact fee | 1% of job value, improvements of $10,000 or more |
The usual Marin HVAC permit, at $13,261, is over the $10,000 roads-fee line, which on its own would add about $130 at that value. The page does not say whether maintenance permits are exempt, so check the invoice before you pay. Prices by home value are on the Marin County HVAC cost page.
Who should do it
A contractor with CSLB's C-20 Warm-Air Heating, Ventilating and Air-Conditioning classification (CSLB). Marin permits carry the license number typed on them, so the number on your permit should match your contract; check it on Check A License.
What 1,640 Marin County HVAC permits show
| Measure | Unincorporated Marin HVAC |
|---|---|
| Permits on homes, October 2023 to September 2026 | 1,640 |
| Contractors | 131 |
| Contractors with a permit in the last 12 months of the file | 63 |
| Usual filed value | $13,261 |
| Middle half of contractors' usual value (44 firms) | $14,000 to $19,250 |
| Approved final (tracked permits a year or more old) | 74.8% |
| Usual days from issue to final | 96 |
| 10th / 90th-percentile contractor (10+ permits) | 55.2% / 91.3% |
| Share held by the five busiest | 53.2% |
| Contractors matched to an active CSLB license | 88.5% |
| Busiest / quietest month | December (132) / August (77) |
Marin is a heating market: filings peak in December at index 132 and bottom out in August at 77, the reverse of hot-summer cities. A furnace or heat pump planned for late summer is easier to book than one after the first cold snap. Permits here close slowly: a usual 96 days, with 9 of 25 busy contractors closing under 70%. Five firms hold 53.2% of permits, so the compare list is short at the top.
See every Marin County HVAC contractor by license and permits finaled →
Related
Look contractors up on the Marin County HVAC list and check licenses with the Marin County contractor license lookup. Past permits on your address: Marin County building permit search. Electrical work for a heat pump: Marin County electrical permit. Other places' rules: do I need a permit for HVAC replacement; national prices: HVAC replacement cost; the checklist: hiring an HVAC contractor. Counts by year: Marin County permit statistics.
What this does not tell you
The filed value is what the contractor wrote on the permit. Finish figures come from the County's inspection file. Our license match uses the number on the permit or the business name; 9.9% of contractors did not match. The County's site blocks automated reading, so its pages were read through a page reader.
How we know this
Permit types and steps are quoted from the Marin County Community Development Agency's How to apply for a building permit and How permits work pages, and fee components from its Fee Explanation page, read 23 October 2026. Counts are unincorporated Marin County HVAC permits on homes, October 2023 to September 2026; finished share uses tracked permits a year or more old with an approved final inspection, and license status is our match against CSLB's license file.
Numbers come from Marin County Community Development Agency building permits on homes in unincorporated Marin (the County's open-data permit and inspection files), data through October 19, 2026. Nobody paid to be on this page and nobody can.
Questions
- Do I need a permit to replace a furnace or heat pump in Marin County?
Yes, in unincorporated Marin. The County lists 'ductwork, mechanical appliances, HVAC, exhaust hoods' among its mechanical maintenance permits, issued online with no plans because they replace existing equipment. The cities and towns, such as San Rafael and Novato, issue their own.
- How much is an HVAC permit in Marin County?
The County publishes the parts of the fee, not a flat HVAC amount: state taxes of 0.01% and 0.004% of job value, a 10% planning surcharge and 6% technology fee on the building fees, and a roads impact fee of 1% of value on improvements of $10,000 or more. The portal invoice gives the total.
- How long does an HVAC permit take to close in Marin County?
The permit is issued online. Closing it takes longer: the usual unincorporated Marin HVAC permit in our file reached an approved final 96 days after issue, and 74.8% of tracked permits a year or more old had one.
- Does a heat pump need an electrical permit in Marin County?
If the job adds a circuit or upgrades the service, yes: circuits and service upgrades are on the County's electrical maintenance permit list. Many installers file both on one job.
- How much does a new HVAC system cost in Marin County?
The usual unincorporated Marin HVAC permit was filed at $13,261, and the middle half of contractors usually filed between $14,000 and $19,250. That is the value on the permit, not a quote.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Marin County building permit search: how to look up permits on an address
- Ames building permit search: how to look up permits on an address
- Do I need an HVAC permit in Ames? Yes: what is exempt, homeowner permits, the $56.23 base fee and inspections
- Do I need an HVAC permit in Anaheim? The mechanical permit for a furnace or AC change-out, fees and inspections
- Do I need an HVAC permit in Sacramento County? Yes, and it issues online: who pulls it, inspections, and timing
- Do I need an HVAC permit in Saint Paul? Furnace and AC permits, explained
For one city
- Marin County contractor license lookup: CSLB classifications, County permits and what they show
- Home improvement costs in unincorporated Marin County, CA (2026): what 15 kinds of jobs were filed at
- Do I need an electrical permit in Marin County? Maintenance permits for circuits and panels, minor improvement permits for solar and generators
- How to apply for a building permit — Marin County Community Development Agency (accessed 2026-10-23)
- How permits work — Marin County Community Development Agency (accessed 2026-10-23)
- Building Permits: Fee Explanation — Marin County Community Development Agency (accessed 2026-10-23)
- CSLB Licensing Classifications (2026-10-22)
- Check A License — CSLB (2026-10-23)