Unincorporated Marin is the area outside the county's eleven cities and towns, such as Kentfield, Tam Valley, Inverness and Marinwood; San Rafael, Novato and the other towns issue their own permits.
What each job was filed at
"Usual" is the middle permit: half were filed for less, half for more. "Middle half of firms" takes every firm with three or more permits in the trade, finds each firm's usual job, and shows the band the middle 50% of firms sit in; it is the number to hold a quote against. A dash (—) means we don't show that figure: in the firms column, fewer than eight firms had three or more permits, so there is no band; in the days column, too few permits of that type carry a completion date to give a usual figure.
| Job | Usual filed value | Middle half of firms | Permits (share priced) | Usual days to final | Pages |
|---|---|---|---|---|---|
| EV charger | $2,296 | $1,600–$3,000 | 213 (100.0%) | 64 | cost · compare firms |
| Electrical work | $4,000 | $3,250–$5,500 | 1,464 (99.7%) | 124 | cost · compare firms |
| Water heater | $4,200 | $3,263–$5,989 | 470 (99.8%) | 56 | cost · compare firms |
| Plumbing & gas | $4,858 | $3,300–$9,000 | 460 (100.0%) | 53 | cost · compare firms |
| Windows & doors | $12,214 | $10,000–$16,200 | 488 (100.0%) | 94 | cost · compare firms |
| HVAC | $13,261 | $14,000–$19,250 | 1,640 (99.9%) | 96 | cost · compare firms |
| Roof replacement | $20,421 | $16,500–$25,000 | 1,943 (99.8%) | 58 | cost · compare firms |
| Siding & stucco | $25,498 | $34,000–$69,089 | 204 (98.5%) | 119 | cost · compare firms |
| Solar & battery | $29,222 | $17,952–$38,536 | 1,339 (99.7%) | — | cost · compare firms |
| Foundation & retaining wall | $35,000 | $19,750–$75,000 | 248 (99.2%) | 431 | cost · compare firms |
| Kitchen, bath & remodel | $45,000 | $25,000–$75,000 | 640 (98.9%) | 272 | cost · compare firms |
| Deck & stairs | $50,000 | — | 151 (98.7%) | 335 | cost · compare firms |
| Pool & spa | $70,000 | $35,275–$122,000 | 155 (100.0%) | 466 | cost · compare firms |
| ADU | $205,000 | — | 111 (100.0%) | 555 | cost · compare firms |
| Home addition | $250,000 | — | 134 (98.5%) | 701 | cost · compare firms |
Permits here stay open a long time: 701 days for the usual addition and 466 for a pool. Those days run to the final inspection, not to the end of the work.
What moves the price in Marin County
The home. Each cost page splits firms into thirds by the usual value of the homes they work on (Marin County assessed values from MarinMap parcels). Those are Proposition 13 values, which usually sit well below market value; on that basis the single-family figure is $1,017,000.
| Job | Firms on the least expensive third | Firms on the most expensive third |
|---|---|---|
| Kitchen, bath & remodel | $25,000 | $75,000 |
| Home addition | $150,000 | $380,000 |
| Pool & spa | $38,000 | $147,500 |
| Foundation & retaining wall | $32,720 | $53,600 |
| Roof replacement | $19,090 | $25,400 |
| HVAC | $16,200 | $15,892 |
Figures from each cost page, data of 19 October 2026. Remodels triple and pools nearly quadruple with home value; roofs rise by a third; HVAC doesn't move.
The firm. In pools the ten busiest firms usually file $38,000 a permit, while the 80 firms with fewer than ten permits usually file $98,500 (Marin County pool cost page). In remodels it is $26,000 against $50,000 for 374 smaller firms. The big, busy firms here are filing the smaller jobs.
What a Marin County permit costs
The County's fee explanation page (read 22 October 2026) lists these charges that follow the value of the work:
| Charge | Basis |
|---|---|
| Roads Impact Fee | 1% of the value of the proposed improvements, on improvements valued at $10,000 or more |
| Seismic Motion Instrument Program tax (residential) | 0.01% of the value of the proposed improvements, 50 cent minimum |
| Building Standards Commission "green" tax | 0.004% of the value, $1.00 minimum |
| Planning surcharge | 10% of the building permit application and issuance fees |
| Technology enhancement fee | 6% of the building permit application and issuance fees |
The base Building & Safety fee itself is on the County's separate base-fee schedule, which we did not quote. On the usual $45,000 remodel the Roads Impact Fee alone is $450.
Filed value is not the price
- The fee rides on it. A 1% roads fee above $10,000 is a reason not to round a value up.
- Prop 13 home values. The home-value thirds use assessed values that lag the market, so a recently bought house sits higher than a long-held one of the same market value.
- Few firms in some rows. Deck, ADU and addition have no firm band because fewer than eight firms had three or more permits; read those compare pages permit by permit.
Check a quote in five minutes
- Find your job in the table and open its cost page.
- Put your quote against the "middle half of firms" band. Inside it is normal here; above it, ask what the extra covers.
- Open compare firms, find the contractor, and read its usual filed value, permit count and finished share.
- Ask whether the price includes the County's fees and the final inspection; the usual addition here took 701 days to reach final.
Single-job guides: what is an ADU, home addition cost, roof replacement cost. To check a California licence, see how to check a contractor's license in California.
How we know this
Every row is a permit type with a cost page: Marin County issued at least 100 priced permits of it on homes in unincorporated Marin in the window 2023-10 to 2026-09, making up at least 80% of the type. Usual = median of the permits that carry a value; middle half of firms = 25th to 75th percentile of the usual value of firms with three or more permits in the trade (shown when at least eight firms qualify); days = median from permit issue to final inspection. Home-value thirds and busiest-firm figures are copied from each job's cost page and dated. Fee bases are quoted from the County's fee explanation page linked under Sources.
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.
Compare every Marin County remodeler by usual job and finished share →
Questions
- How much does ADU construction cost in Marin County?
In unincorporated Marin the usual ADU permit was filed at $205,000 across 111 permits. Builders on the most expensive third of homes usually file $200,000, against $100,000 on the least expensive third (Marin County ADU cost page). The usual ADU permit took 555 days from issue to final.
- What is the cost of a home renovation in Marin County?
Kitchen, bath and remodel permits were usually filed at $45,000 (640 permits), with the middle half of 56 remodelers between $25,000 and $75,000. Remodelers on the most expensive third of homes usually file $75,000, three times the $25,000 on the least expensive third.
- How much does HVAC replacement cost in Marin County?
HVAC permits were usually filed at $13,261, across 1,640 permits, with the middle half of 44 HVAC firms between $14,000 and $19,250. Firms on cheaper and dearer homes file about the same ($16,200 against $15,892), so the house is not what moves an HVAC quote here.
- How much does foundation repair cost in Marin County?
Foundation and retaining-wall permits were usually filed at $35,000 (248 permits), but the middle half of 22 firms file anywhere from $19,750 to $75,000. The usual permit stayed open 431 days.
- How much is a building permit in Marin County?
The County's fee page lists a Roads Impact Fee of 1% of the value of the proposed improvements on work valued at $10,000 or more, so a remodel at the usual $45,000 pays $450 of it. On top of the base building fee come a 10% planning surcharge and a 6% technology fee, each on the application and issuance fees.
Build your own list
Every firm with that kind of permit on record. Pick what you value. The list moves.
Related guides
- Home improvement costs in Palo Alto, CA (2026): what 12 kinds of jobs were filed at
- Home improvement costs in unincorporated Sacramento County, CA (2026): what 14 kinds of jobs were filed at
- Marin County contractor license lookup: CSLB classifications, County permits and what they show
- Anaheim contractor license lookup: CSLB classifications, the City's permit report and what it shows
- Home improvement costs in San Francisco, CA (2026): what 10 kinds of jobs were filed at
- Marin County Community Development Agency, Building Permits: Fee Explanation (accessed 2026-10-22)