21 Elm Ave
Woodacre 94973 · Woodacre · Unincorporated Marin · Coordinates: 38.00573, -122.63286
Executive Verdict · Public-Records Synthesis
Zoned R1-B2-SGV in Unincorporated Marin with likely ADU & SB 9 infill eligibility and mapped CAL FIRE high fire hazard severity zone (state responsibility area) due diligence; benchmark value $1,182,000 ($1,040,000–$1,324,000).
Upsides & Opportunities
- ✓ ADU & SB 9 infill pathways screen as likely eligible
Zoned R1-B2-SGV supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 18,513 sq ft lot.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
- ✓ Documented permitted upgrades (+$5,120 contributory est.)
Public building records show issued construction/renovation work on this parcel (5 total permits, latest Nov 15, 2022).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
Watchouts & Due Diligence
- ! Mapped flood awareness zone (Zone X: minimal flood hazard)
all of the lot of the parcel intersects Zone X: minimal flood hazard. Outside mandatory federal SFHA insurance rules, but check local drainage and finished-floor requirements.
Source: FEMA National Flood Hazard Layer (parcel polygon)
- ! CAL FIRE High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot of lot)
Located in a mapped Fire Hazard Severity Zone. Expect Chapter 7A ignition-resistant building standards, defensible-space inspections, and stricter property insurance underwriting.
Source: CAL FIRE FHSZ (map Apr 1, 2024)
- ! Delayed or open permit activity on this parcel
Plumbing / water heater / sewer (169148): Issued after 2 mo — slower than 90% of plumbing / water heater / sewer permits in Unincorporated Marin (median 0d, 90th pct 0d, n=2,211).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
- ! 4 slow or stalled nearby projects within ½ mile
Closest lead: New home at 80 Fire Rd (0.26 mi NE, issued). Inspect timeline history before assuming near-term completion.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · HCD APR (½-mile radius)
Parcel & Assessor
- Lot size:
- 18,513 sq ft (0.42 ac)
- Assessor use:
- Single-Resid. - Improved
- Addresses on lot:
- 21 ELM AVE
Zoning & Land Use
R1-B2-SGV — Residential Single Family (Unincorporated Marin)
State Housing Pathways Screen (ADU & SB 9)
- ADU or junior ADULikely eligible
Zoned R1-B2-SGV (single-family residential): state law allows ADUs where homes are allowed.
- SB 9: two homes on the lotLikely eligible
Zoned R1-B2-SGV, a single-family residential zone.
- SB 9: split into two lotsLikely eligible
Zoned R1-B2-SGV, a single-family residential zone. The lot is 18,513 sq ft by the assessor, room for two lots of at least 1,200 sq ft, each at least 40% of the original.
Mapped Hazard Zones on This Lot
- CAL FIRE Fire Hazard Severity Zone
- High Fire Hazard Severity Zone (State Responsibility Area) (all of the lot, map Apr 1, 2024)
- FEMA National Flood Hazard Layer
- Zone X: minimal flood hazard (all of the lot) · FIRM panel 06041C0275D, effective May 4, 2009
- CGS Alquist-Priolo Earthquake Fault Zone
- Not in an Alquist-Priolo Earthquake Fault Zone
Surrounding Rent & Value Benchmarks (Public Records)
Range: $1,040,000 – $1,324,000 · Status: Off market
HUD Small Area FMR (ZIP 94973) · FY 2026
Studio $2,080 · 1BR $2,510 · 2BR $3,020 · 3BR $3,860 · 4BR $4,000
Developments Deserving Closer Investigation & Active Area Builders
- Plumbing / water heater / sewer (169148) (Issued)On this parcel
Issued after 2 mo — slower than 90% of plumbing / water heater / sewer permits in Unincorporated Marin (median 0d, 90th pct 0d, n=2,211).
- New home at 80 Fire Rd (Issued)0.26 mi NE
Active in "Issued" for 4.1 yr (first record Sep 28, 2022) with no new permit activity recorded in 3.5 yr. High-impact scale (1 housing unit, $2,000,000 declared valuation across 1 permit).
- New home at 15 Edgewood Dr (Applied)0.39 mi SW
In "Applied" for 6.1 yr (since Oct 22, 2020), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121).
- New home at 10 Holly Ln (Applied)0.45 mi W
Active in "Applied" for 14 mo (first record Sep 17, 2025) with no new permit activity recorded in 14 mo.
Entity-resolved builders & contractors in ½ mile: Owner (1 on parcel, 5 in ½ mi · New garage / accessory structure); Tesla Energy (1 on parcel, 1 in ½ mi · Solar / battery storage); Safe And Warm Chimney Service (1 on parcel, 1 in ½ mi · HVAC / heat pump); Gendron Electric (1 on parcel, 1 in ½ mi · Electrical / panel); Owner Builder (9 in ½ mi · New garage / accessory structure).
Permit & Project History on This Parcel (5 permits, 0 grouped projects)
| Record # | Category | Status | Applied / Issued | Valuation | Description |
|---|---|---|---|---|---|
| B31763 | Electrical / panel | Issued | Iss. Nov 15, 2022 | $1,000 | Replace electrical service wire down mast and replace weather head — Service Upgrade |
| 169148 | Plumbing / water heater / sewer | Issued | Iss. Aug 23, 2021 | $15,400 | Generator |
| 155907 | Solar / battery storage | Issued | Iss. Jul 5, 2017 | $6,253 | P V Sys 4.225 K W - Express - Change To E-Insp 7/17/17 |
| 143453 | HVAC / heat pump | Issued | Iss. Jul 23, 2014 | $5,000 | Install Propane Burning Fireplace Insert |
| 142842 | Plumbing / water heater / sewer | Issued | Iss. Jun 4, 2014 |