Mill Valley 94941 · Tamalpais · APN 048-233-13 · Unincorporated Marin
Zoned RSP-1.5 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 $1,973,000 ($1,736,000–$2,210,000).
Zoned RSP-1.5 supports ministerial ADU/JADU review plus SB 9 both two-unit development and ministerial urban lot split on a 3,223 sq ft lot. Local precedent is active with 4 ADU permits within ¼ mile over the last 36 months.
Source: Unincorporated Marin zoning · CA Gov. Code 66314 & 65852.21
Public building records show issued construction/renovation work on this parcel (3 total permits, latest Mar 8, 2022).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (parcel APN)
50 substantial renovation & housing permits over 24 months (20.5 per 1,000 parcels vs. 16.4 citywide baseline) (#3 of 22 neighborhoods).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (Tamalpais)
Automated synthesis of indexed municipal, county, state, and federal public records — informational context only, not a formal appraisal, survey, or legal/tax determination.
$1,973,000
Benchmark range: $1,736,000 – $2,210,000
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)
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)
New garage / accessory structure (89592): Pending in review for 4.7 yr (10.4× the 164d median) — slower than 90% of new garage / accessory structure permits in Unincorporated Marin (median 164d, 90th pct 485d, n=356).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) (review-time benchmark)
Closest lead: New home at 560 Alta Way (0.36 mi SE, applied). Inspect timeline history before assuming near-term completion.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · HCD APR (½-mile radius)
Since November 2024 within ½ mile: 1 homes completed, 7 permitted, 4 proposed or in review; 3 demolitions.
15 projects with a record in this window, grouped by us from permits and State housing reports. Units are as proposed on each project's latest record and counted at its current stage.
422 permits within ½ mile since November 2024
The map shows new construction, ADUs, demolitions, additions, and renovations. Routine systems work (roofs, HVAC, water heaters) is counted but not mapped. Unit counts are as stated on permits.
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: permits located by parcel, ½ mile radius · Retrieved Nov 13, 2026
Public-records benchmark estimate combining Zillow Home Value Index (Data provided by Zillow), Census ACS 5-year estimates, parcel land-use/lot characteristics, and issued building permits. Not an official appraisal.
Permit counts, by the date issued (or applied, if not yet issued). Lot splits are planning cases, which we don't have.
We read public zoning and hazard maps against state law (ADUs: Gov. Code 66314; SB 9: Gov. Code 65852.21 and 66411.7). Local rules, title, tenancy history and site conditions can change the answer. Check with Unincorporated Marin's planning department before relying on it.
Sources: County of Marin GIS (MarinMap), Zoning (11 cities and unincorporated Marin) (retrieved Nov 13, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the State Responsibility Area (effective 2024-04-01) (retrieved Nov 9, 2026) · CAL FIRE Office of the State Fire Marshal, Fire Hazard Severity Zones in the Local Responsibility Area (map dated 2025-03-24) (retrieved Nov 9, 2026) · FEMA, National Flood Hazard Layer — flood hazard zones (retrieved Nov 9, 2026) · FEMA, National Flood Hazard Layer — FIRM panels (retrieved Nov 9, 2026) · California Geological Survey, Alquist-Priolo Earthquake Fault Zones (retrieved Nov 9, 2026) · Zoning classes: our classification of RSP-1.5 as single-family residential, checked against the zone description on Oct 24, 2026
Chronological history of building permit applications and issuances, snapshot-dated status changes, State housing entitlements, surrounding development within ½ mile, and area home-value trends.
Permit issued and active for 13.2 yr (first record Sep 4, 2013), with no completion or new permit record in 12.5 yr. · 1 unit · $200,000 declared valuation
Permit issued and active for 12.4 yr (first record Jun 2, 2014), with no completion or new permit record in 12.4 yr. · $400 declared valuation
Permit issued and active for 12.4 yr (first record Jun 10, 2014), with no completion or new permit record in 12.3 yr. · $12,500 declared valuation
Permit issued and active for 12.2 yr (first record Sep 10, 2014), with no completion or new permit record in 12.1 yr. · $5,000 declared valuation
Permit issued and active for 12.6 yr (first record Mar 27, 2014), with no completion or new permit record in 12 yr. · 1 unit · $650,000 declared valuation
Permit issued and active for 11.7 yr (first record Mar 9, 2015), with no completion or new permit record in 11.4 yr. · 1 unit · $780,000 declared valuation
Nearby other (529 Brookline Way): First appeared in published agency feed
Record B49083 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (1075 Erica Rd): First appeared in published agency feed
Record B49072 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (1217 Waterview Dr): First appeared in published agency feed
Record 94643 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (908 Vernal Way): First appeared in published agency feed
Record B49065 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (910 W California Ave): First appeared in published agency feed
Record B49064 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby other (1212 El Cide Ct): First appeared in published agency feed
Record B49060 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby windows / doors / siding (875 Chamberlain Ct): First appeared in published agency feed
Record B48958 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Nearby electrical / panel (201 Hawthorne Ave): Description text was updated
Record B48724 · Detected between snapshots
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Snapshot diff within ½ mile
Latest published Zillow Home Value Index (ZHVI) update
Changed from $1,980,059 in September 2025 to $2,181,389 in September 2026.
Source: Zillow Home Value Index (ZHVI) · Data provided by Zillow · Geography: ZIP 94941 (not a parcel appraisal)
200 Chapman Rd (200 A - Adu) · 1 unit · $440,000 valuation
Records span Dec 30, 2025 to Sep 2, 2026 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
351 N Ferndale Ave · $25,000 valuation
Records span May 26, 2026 to Sep 1, 2026 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
328 Melrose Ave (Adu 328a) · 1 unit · $100,000 valuation
Records span Sep 12, 2024 to Aug 26, 2026 (1 permit).
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
916 Valley View Ln · 1 unit · $5,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
81 Skyline Ter · 1 unit · $85,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
526 Alta Way · 1 unit · $550,000 valuation
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) & HCD APR (grouped project within ½ mile)
Cross-referenced intelligence from our historical development graph—connecting parcels, permits, entity-resolved builders, empirical review-time distributions, and neighborhood renovation trends.
Explore full Unincorporated Marin development graph →In "Applied" for 3.3 yr (since Aug 10, 2023), exceeding the 253d median and 686d 90th percentile for new single-family home permits in Unincorporated Marin (n=121). High-impact scale (1 housing unit, $975,000 declared valuation across 1 permit).
Pending in review for 4.7 yr (10.4× the 164d median) — slower than 90% of new garage / accessory structure permits in Unincorporated Marin (median 164d, 90th pct 485d, n=356).
Active in "Issued" for 3.1 yr (first record Oct 12, 2023) with no new permit activity recorded in 2.6 yr. High-impact scale (1 housing unit, $850,000 declared valuation across 1 permit).
Active in "Issued" for 4.3 yr (first record Aug 5, 2022) with no new permit activity recorded in 3.5 yr. High-impact scale (1 housing unit, $950,000 declared valuation across 1 permit).
Active in "Issued" for 11.7 yr (first record Mar 9, 2015) with no new permit activity recorded in 11.4 yr. High-impact scale (1 housing unit, $780,000 declared valuation across 1 permit).
Active in "Issued" for 8.1 yr (first record Oct 1, 2018) with no new permit activity recorded in 7.5 yr. High-impact scale (1 housing unit, $780,000 declared valuation across 3 permits).
Substantial improvements (additions, interior remodels, ADUs, commercial TI, and new builds) across 2,439 parcels
−7.7% YoY
City baseline: 16.4 / 1k
50 in trailing 24m
Includes 16 ADUs
| Builder / contractor | Primary specialty | Here / ½ mi | ½ mi valuation | Citywide 24m trend |
|---|---|---|---|---|
| Solar Technologies | Solar / battery storage | 1 on parcel1 in ½ mi | $20,270 | 0 vs 0 prior |
| Ste Electric | Electrical / panel | 1 on parcel1 in ½ mi | $1,200 | 0 vs 0 prior |
| Owner Builder Recent nearby: 351 N Ferndale Ave (Sep 1, 2026) | Remodel / interior alteration | 59 in ½ mi | $7,295,907 |
| Permit category | Sample (n) | 25th pct | Median (50th) | 75th pct | 90th pct | Recent 24m median |
|---|---|---|---|---|---|---|
| New single-family home | 121 | 166d | 253d | 456d | 686d | 211d(vs 273d prior) |
| New multifamily / condos / mixed-use | 21 | 272d | 292d | 293d | 313d | 293d(vs 197d prior) |
| New garage / accessory structureOn this parcel | 356 | 104d | 164d | 294d | 485d | 159d(vs 205d prior) |
HUD Small Area Fair Market Rent · ZIP 94941
HUD FY 2026 · 40th-percentile gross rentCensus ACS 5-year median gross rent (all bedroom counts combined):
Area home-value benchmarks (not an appraisal)
ZIP & neighborhood mediansUnder California Proposition 13, the seller's historical assessed value does not carry over to a buyer. On sale, the parcel is reassessed at the purchase price: 1.00% base rate ($19,750/yr) + local voter-approved bond debt ($2,963/yr) + fixed direct levies/Mello-Roos ($450/yr).
Mapped hazard zone insurance context on this parcel:
Model adding a backyard ADU or garage conversion under California's Prop 13 blended new-construction assessment (existing house & land tax base stays intact; only ADU build cost is assessed) and SB 13 impact-fee rules.
−$109,615/yr
Cash needed: $434,500
NOI: $10,225/yr
P&I: $9,987/mo
For $0/mo net cash flow
At $3,950/mo gross rent
| Scenario | Assumptions | Year 1 Rent | Year 1 Cash Flow | Cash-on-Cash | Break-Even Rent | Year 5 Cash Flow |
|---|---|---|---|---|---|---|
| Conservative | −8% starting rent, +3% vacancy, +3% combined maintenance/CapEx, 1.5%/yr rent growth | $3,634/mo | −$9,588/mo | -26.5% | $17,018/mo | −$9,613/mo |
| Base (your inputs) | Your entered assumptions, 3.0%/yr rent growth | $3,950/mo | −$9,135/mo | -25.2% | $15,752/mo | −$8,935/mo |
| Optimistic (cap-limited) | +6% starting rent, 3% vacancy, 4.5%/yr rent growth (capped by AB 1482 ceiling of 8.6%/yr) | $4,187/mo | −$8,874/mo | -24.5% | $15,386/mo | −$8,420/mo |
Rental regulatory context (informational only — not legal advice):
California AB 1482 (Tenant Protection Act, Civ. Code § 1947.12) caps annual rent increases at 5% + local CPI (max 10%) on covered properties.
Expand Living Room; Add Bedroom, Bath And Interior Stair @ Basement; Covered Porch; Deck S M F D M V S D
125A to 125A like for like — Service Upgrade
3.27kw Rooftop Photovoltaic
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Geography: parcel (APN) · Retrieved Nov 13, 2026 · Received and issued dates come from the County of Marin. The county publishes no final or expired status, so an issued permit stays 'Issued' after the work is done.
No housing activity reported to the State for this parcel (2018–2025 reports).
Source: California HCD, Housing Element Annual Progress Report — Table A2 · Geography: project (parcel) · Retrieved Nov 9, 2026 · From Unincorporated Marin's Housing Element Annual Progress Reports. A project can appear in several report years as it moves from entitlement to permit to completion.
Source: County of Marin GIS (MarinMap), Zoning (11 cities and unincorporated Marin) · Geography: zoning district polygon at parcel point · Retrieved Nov 13, 2026
0.07 acres
Assessor's classification for assessment purposes. This is not zoning.
1231 WATERVIEW DR
Source: County of Marin GIS (MarinMap), Parcels · Geography: parcel · Retrieved Nov 13, 2026
Search by parcel number 048-233-13. Assessed value is not market value.
Search by parcel number 048-233-13 (Marin County Tax Collector)
Permits issued in unincorporated Marin in the past 48 months. Each city keeps its own records.
The official flood hazard map for this location. Our reading of it is under What could be built here.
This site does not show owner names.
| 226 vs 240 prior−6% |
| Owner Recent nearby: 351 Melrose Ave (Sep 18, 2025) | Remodel / interior alteration | 33 in ½ mi | $2,389,900 | 25 vs 15 prior+67% |
| Foley Built Recent nearby: 328 Ridgewood Ave (Dec 11, 2024) | Addition (adds square footage) | 5 in ½ mi | $1,351,000 | 2 vs 3 prior |
| Spellbound Construction Recent nearby: 124 Reed St (Oct 30, 2014) | Addition (adds square footage) | 4 in ½ mi | $873,000 | 2 vs 1 prior |
| Philip Kline Gen Cont Recent nearby: 206 Hawthorne Ave (Dec 5, 2016) | Remodel / interior alteration | 4 in ½ mi | $223,000 | 0 vs 0 prior |
| Barton Design And Constuction Recent nearby: 1201 Waterview Dr (Jun 4, 2018) | Remodel / interior alteration | 3 in ½ mi | $840,000 | 0 vs 0 prior |
| Gannon Construction Recent nearby: 969 W California Ave (Sep 16, 2026) | Remodel / interior alteration | 3 in ½ mi | $600,000 | 4 vs 4 prior |
| Lamperti Contracting And Design Recent nearby: 1125 W California Ave (Feb 1, 2024) | Remodel / interior alteration | 3 in ½ mi | $344,716 | 2 vs 7 prior |
| Accessory dwelling unit (new or conversion) | 298 | 120d | 204d | 331d | 549d | 214d(vs 181d prior) |
| Addition (adds square footage) | 316 | 103d | 160d | 249d | 440d | 157d(vs 167d prior) |
| Remodel / interior alteration | 1,054 | 36d | 83d | 148d | 266d | 112d(vs 77d prior) |
| Commercial tenant improvement | 81 | 99d | 148d | 233d | 443d | 152d(vs 150d prior) |
| Solar / battery storageOn this parcel | 2,977 | 0d | 0d | 0d | 2d | 0d |
Source: County of Marin Community Development Agency, Building Permits (unincorporated Marin) · Computed from issued permits with recorded application and issuance dates over the trailing 60 months. Categories with fewer than 20 permits are excluded.