3845 Bloomfield

ownership

7 min read

Ownership — The Mosiman Family

3845 Bloomfield Rd · APN 025-100-006 Pulled: 2026-05-11

Legal title: MOSIMAN STEVEN T TR & MOSIMAN HELEN C TR (Steven Thomas Mosiman + Helen C. Mosiman, as co-trustees of a family trust). Acquired 2008-10-24 for $1,100,000 (Doc # 2008R096841); trust transfer 2009-06-15 (Doc # 2009R057779). Holding period ~17.6 years as of May 2026.

The original briefing premise — “the owners bought the property for the sons to become dirt bikers and now they all are and the owners live in LA and no one really uses the property” — is partially right, partially wrong:

  • ✅ The dirt-bike angle is correct. Both sons are professional motocross/supercross racers, and there is a permit-graded motocross track on the parcel (GRD09-0106 → GRD12-0080 → GRD15-0104, ”@ 100%” complete per the 2015 permit description, engineered by Adobe Associates).
  • ✅ The willingness to sell is the load-bearing piece of info — per the user briefing, Steve and Helen are open to a sale. The off-market path is appropriate.
  • ❌ The “owners live in LA” framing is wrong. The Mosimans live at [residence — see CA SoS officer-address filing] — same 95472 zip code as the subject property, ~3 miles away. Steve runs a $42M Sonoma/Napa-area construction company (Sheehan Construction, Inc.). They are deep-roots locals, not absentee SoCal owners. The “no one uses it” framing is plausible: Michael’s racing career has wound down through injuries, Josh moved into journalism, so day-to-day use of the track has likely dropped significantly from the 2010-2018 peak.

Steven Thomas Mosiman (“Steve”)

Full nameSteven Thomas Mosiman
Date of birthAge 68 (May 2026) — confirmed via public records
Residence[residence — see CA SoS officer-address filing] (CA SoS officer-address for Sheehan Construction)
ProfessionPresident / CEO, Sheehan Construction, Inc.
Origin storyCo-founded Sheehan Construction with Tom Sheehan in November 1998 (“two guys and a big truck”). Steve was running a large framing operation; Tom was running a successful layout business. They merged. Incorporated 1999-05-26 as current entity (CA SoS Doc # 2139847).
Sheehan Construction scale~$42M revenue, ~500 employees, residential framing / single-family housing construction across NorCal
CSLB licenses767115 (Active – General Building), 809970 (Active – General Building), plus older inactive licenses 762230 / 665915 / 653819 / 519338 / 910269
Tom Sheehan (partner)Thomas F. Sheehan — Vice President / Secretary / CFO / Registered Agent / CSLB RMO (Responsible Managing Officer). Sebastopol-based at 8507 Mill Station Rd.
Other Sheehan principalsJeremy James Sheehan and Kevin Brian Sheehan (Sole Owners on BuildZoom roster — likely Tom’s sons; run the Los Gatos operation)

Sheehan Construction offices

LocationAddressPhone
Napa (main)477 Devlin Rd Ste 108, Napa, CA 94558(707) 603-2610
Sebastopol1418 Gravenstein Hwy S, Sebastopol, CA 95472(707) 823-8479
Los Gatos23889 Summit Rd, Los Gatos, CA 95033(408) 569-7293
Principal address (CA SoS)1205 Hwy 116 S, Sebastopol, CA 95472—
Websitewww.sheehanconstruction.com (currently unresponsive to public WebFetch — placeholder; B2B contractor doesn’t need consumer-facing site)—
LinkedInhttps://www.linkedin.com/company/sheehan-construction—

Helen C. Mosiman

Age~55 (per aggregator snippets)
ProfessionNo independent professional record surfaced. Referenced in motocross interviews of her sons as the family’s racing logistics anchor (“Mom has been at every race except Tennessee”).
Residence[residence — see CA SoS officer-address filing] (same as Steven)

The two sons (both public motocross figures)

Josh Mosiman (older son)

  • Former pro Supercross/MX racer. 2018 National #71. Pro debut Hangtown 2016.
  • Currently Assistant Editor / test rider at Motocross Action Magazine (MXA).
  • Married (per 2021 MXA “Flashback Friday” referencing his wife as mechanic at Hangtown 450).
  • Author page: https://motocrossactionmag.com/author/joshm/
  • Public Instagram: @joshmosiman

Michael Mosiman (younger son)

  • Born July 16, 1999, in Sebastopol, CA.
  • Active pro motocross/supercross racer. Factory teams: Rockstar Energy Husqvarna Factory Racing (2017–2020) → Troy Lee Designs Red Bull GasGas (2021–2023) → Monster Energy Star Racing Yamaha (2024–present).
  • 2022 San Diego Supercross 250SX West winner; 3rd in 2022 250SX West championship.
  • Multiple serious injuries — broken neck 2022, head injury 2023, neck fractures 2024; held a retirement party in 2024; cleared and returned to competition 2025; expected to race 2026 250SX West.
  • Wikipedia: https://en.wikipedia.org/wiki/Michael_Mosiman
  • Pro Motocross: https://promotocross.com/rider/michael-mosiman
  • SupercrossLive: https://www.supercrosslive.com/rider/michael-mosiman/
  • Public Instagram: @_michaelmosiman

Contact channels

The Mosimans are willing sellers per the user briefing — this is normal off-market real-estate outreach, not a cold approach to a closed counter-party.

ChannelHow
Steve’s residence — best opener[residence — see CA SoS officer-address filing]. Steve & Helen live here. A hand-written letter, addressed to “Steve & Helen Mosiman,” introducing yourself as the son-in-law of the 4201 Bloomfield owner and asking for a 15-minute conversation is the strongest first move.
Sheehan Construction Napa office477 Devlin Rd Ste 108, Napa, CA 94558 — phone (707) 603-2610. Steve answers business calls. Frame the call: “Hi, this is [name], my in-laws own 4201 Bloomfield Rd next to your Sebastopol property — could I get 15 minutes with Steve about a neighboring-land question?”
Sheehan Construction Sebastopol office1418 Gravenstein Hwy S, Sebastopol — phone (707) 823-8479. Tom Sheehan’s registered-agent address; Steve is often there. Closer to the property.
3845 Bloomfield Rd direct mailLetter addressed to “Steve & Helen Mosiman, Trustees” lands at the property. Trustees check it. Lower-priority than the residence.
Sheehan Construction LinkedInhttps://www.linkedin.com/company/sheehan-construction — formal/slow channel. Limited org footprint on LI (~17 followers, 9 employees listed). Steve does not appear to maintain a personal LinkedIn.
Josh Mosiman (son)Public MXA author email or Instagram @joshmosiman. Useful only for a soft warm-up framed around motocross or the property’s history — not for a real-estate ask.
Mutual neighbors / introducersFurlong (3883, just N — APN 025-100-004), Birse (3858 — APN 025-100-024), LaForge (3225 vineyard, far N — APN 025-100-043). Steve’s been on Bloomfield Rd 17+ years; everyone knows everyone. A coffee at Wischemann Hall, the Freestone bakery, or Wild Flour Bread arranged through any of them would be a natural surface for the conversation.

Tactical note on framing

A spreadsheet-led “we’d like to buy your land below comp” approach to a NorCal construction-industry CEO who has owned, surveyed, engineered, and physically built out this property for 17 years is the wrong way in. The right approach respects:

  1. It’s the family’s training ground. Even with Michael’s career winding down and Josh in journalism, the property holds emotional weight. Don’t dismiss the motocross track as a “negative” to smooth over.
  2. Steve builds for a living. He’ll see through any pitch that under-prices materials or improvements. The on-the-ground value reflects the engineered track, drainage, three structures, and the family’s investment.
  3. He’s locally connected. Word of unprofessional approaches spreads at Sonoma rotary lunches in 48 hours.
  4. He paid $1.1M in 2008. Anchored expectations matter. He’s not going to consider a “below comp” number. The freshest direct comp — your in-laws’ $2.485M Dec 2025 acquisition at 46.15 ac next door — implies a clearing price for 3845 in the $2.5–3.0M range, and he’ll know that math.
  5. The right number, at the right time, through the right introducer. Use the residence letter or neighbor channel first. Failing those, a phone call to Sheehan Napa.

Sources

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