4201 Bloomfield Road — Pre-Application Feasibility Brief

Our overriding goal is to design something that lands cleanly — we would rather adjust the concept now than discover a classification problem at plan check. This brief states the proposal and lists the determinations we are seeking, organized by topic. We are glad to bring it to a formal Project Review meeting.

The proposal

On a new building pad at the north edge of the parcel's oak grove: three independent, freestanding structures — the ADU and two detached home offices — none sharing a wall or roof, each separated by open space (we intend ≥ 10 ft between structures). Separately, a detached 3-car garage on the eastern part of the parcel, below the hill near the existing developed area.

North pad · dwelling

Main ADU

~1,185 sqft · 2 bed / 2 bath · single story. A ministerial ADU under Gov. Code §65852.2 (we understand the parcel allows up to two ADUs).

North pad · accessory

Office — West

~257 sqft · home office / workspace. Habitable, with a bathroom. No kitchen, no sleeping room.

North pad · accessory

Office — East

~257 sqft · identical to West. Habitable, with a bathroom. No kitchen, no sleeping room.

East · accessory

Garage (3-car)

~700 sqft · vehicle storage. Proposed straw-bale walls on a slab foundation. No kitchen, no sleeping room.

Construction: timber frame (ADU + offices) and load-bearing straw-bale (garage); wood + metal cladding; low-slope roofs; substantial glazing to the northwest view; pier/post or slab foundations on the sloping ground. WUI Chapter 7A-compliant exteriors; Title 24 solar on the ADU. This brief addresses land-use feasibility and classification; interior layouts, finishes, and landscape elements are not part of the question.

Property & existing conditions

Existing structures (to remain): the 1988 single-family dwelling (~3,456 sqft; VR permit ZPE16-0070 was revoked at transfer and is not relied upon); a 1,152 sqft former goat-dairy structure legalized as a non-dwelling (BLD03-1684); the private well; and a septic system documented for 1 unit / 4 bedrooms (SDS #1342, 1988).

Disclosed history (all files closed): two prior code-enforcement cases cited the former dairy barn as an illegal second dwelling (VBU02-0038, VPL02-0039, VBU05-0538). We are aware of this record and specifically want to design the new accessory structures so there is no ambiguity about their non-dwelling status.

What we need confirmed

AUse, classification & densityCentral question

Confirm the two detached office structures qualify as by-right accessory structures — not guest houses or dwellings. We intend two detached buildings used as home offices: habitable, each with a bathroom (needed for the workspace), but with no kitchen (no cooking or food prep/storage) and no sleeping room. Specifically, please confirm:
1. they are permitted by building permit only — no use permit — and with no per-parcel numeric limit;
2. a bathroom alone (no kitchen, no sleeping room) does not reclassify them as a guest house, "guest room," or dwelling unit;
3. the guest-house standards (≈640 sqft cap, one-per-parcel, within 100 ft of the primary dwelling) therefore do not apply; and
4. what specific plan features the County uses to keep such a building unambiguously an office/accessory structure (e.g., closets, extent of plumbing, square footage, finishes), so we can design to that line.

Is there a maximum size and/or height for habitable accessory structures in the LEA district?
Are there limits on the total number of structures or on lot coverage — here we'd have 1 dwelling (ADU) + 3 accessory structures (2 offices, 1 garage), alongside the existing SFD and legalized barn?
Do the existing SFD and the legalized non-dwelling barn constrain any of the above?

BDetached garage & straw-bale construction

Confirm a detached 3-car garage (~700 sqft, vehicle storage, no kitchen / no sleeping room) is a by-right accessory structure at the proposed eastern location (below the hill, near the existing developed area) — building permit only, under LEA accessory-structure setbacks.
1. We intend to build it with load-bearing straw-bale walls on a conventional slab foundation. Please confirm straw-bale is acceptable and the path: the prescriptive CRC Appendix AS (Strawbale Construction) route per Permit Sonoma Technical Bulletin B-31, vs. an engineered design (architect/engineer stamp + special inspections), and how the required plaster skin and WUI Chapter 7A ignition-resistance requirements apply to straw-bale in this Moderate FHSZ / SRA.

CADU specifics (ministerial)

Confirm the size cap (≤1,200 sqft), height limit, and that state ADU setback minimums (we understand 4 ft side/rear) govern the ADU.
Confirm the fee picture (we noted ≈$13K impact + ≈$4–5K review at the counter) and whether the accessory structures carry separate fees.
Confirm the Title 24 solar PV requirement for the ADU and acceptable compliance paths.
Confirm the fire-sprinkler requirement (CRC R313) for the dwelling, and whether the offices or garage require sprinklers.
Confirm the 60-day ministerial review timeline for the ADU.

DSetbacks & separation between structures

Confirm property-line setbacks: ADU under state minimums; accessory structures under LEA base (front 55 ft from road centerline / side 10 ft / rear 20 ft) — and that none are binding given interior siting.
Confirm the minimum separation that keeps each building "detached" (we understand a ≥6 ft open-to-sky yard; we intend ≥10 ft on the north pad).
At our proposed spacing, confirm the building-code fire-separation requirements (CRC R302.1) for exterior-wall rating and window-opening area on facing walls, and that ≥10 ft between buildings permits unprotected glazing.

ECombining districts — OAK · RC50/50 · SR

OAK: the ADU pad sits at the north edge of the oak grove. What triggers oak-woodland review, what is the drip-line standard, and will an arborist report, tree survey, or mitigation be required? Do the offices (sited away from the grove) trigger OAK at all?
RC50/50: please confirm the location of any designated watercourse near the pad and that our structures and access clear the 50-ft riparian setback. May we obtain the GIS overlay layers?
SR: what height, materials, or visibility standards from the Bloomfield Rd scenic corridor apply under ministerial review? Do low-slope, non-reflective, earth-toned structures satisfy them?

FWell & septic

Confirm the well classification (noted as Class 2 at the counter) supports the added demand.
The existing OWTS is documented for 1 unit / 4 BR (SDS #1342). How do the ADU (2 BR) plus the two office bathrooms count toward OWTS design flow, and please confirm a new or expanded OWTS design (Type III findings / perc) is the path. (Our civil engineer, BC Engineering, is engaged.)
Confirm the sanitary setbacks governing siting — well-to-leach-field (we understand 100 ft), tank-to-well, structure-to-components — and point us to the OWTS Manual table.

GBuilding · fire · WUI

Confirm Chapter 7A WUI requirements (ignition-resistant exterior, ember-resistant vents, Class A roof) apply to all four structures.
The ADU pad is adjacent to the protected oak grove. How do we reconcile defensible space (PRC 4291, 100 ft) with the OAK overlay's tree protection — is a vegetation-management plan (limbing + understory reduction, retaining mature oaks) the accepted approach?
What fire-apparatus access / turnaround and any fire-flow or water-storage requirements apply in the SRA (Bloomfield VFC / Cal Fire)?

HGrading & access

Confirm the grading-permit threshold (we noted >50 cy) for the building pad, the garage pad, and pier/post foundations on the sloping site, and the geotechnical expectations (expansive soils, Seismic Design Category D).
Confirm when an Encroachment (ENC) permit is triggered for access work near the Bloomfield Rd right-of-way. (We are also reviewing the recorded 50-ft Pullin easement.)

IProcess, submittal & sequencing

Recommended sequencing: we expect to permit the ADU first (ministerial). May the two offices and the garage be submitted concurrently, or should they follow? Does any element push into discretionary review?
Required electronic submittal format and file-naming convention.
Do you recommend a formal Project Review (pre-application) meeting for this multi-structure plan, and how do we schedule it?

JPrior record

Please confirm the closed violations (VBU02-0038, VPL02-0039, VBU05-0538) and the revoked VR permit (ZPE16-0070) pose no obstacle — and advise what we should proactively document to demonstrate the new offices are genuine accessory structures, not dwelling conversions, given the parcel's history.

The proposal

Property & existing conditions

What we need confirmed

Reference materials we can provide