Local zoning · Suisun City

Suisun City — Historic Preservation

Q: Where are the Waterfront District design criteria I must follow?

The ARB requires work on local-register properties in the DWSP to follow the design criteria established by the Waterfront District Specific Plan; the ARB chapter references Chapter 18.26 as the implementing design text (see § 18.78.020.A and § 18.78.030 ). The explicit DWSP/Chapter 18.26 text was referenced but was not reproduced in the retrieved materials — verify with Development Services and request Chapter 18.26 /DWSP design guidelines .

Historic Preservation under the Suisun City local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

This page summarizes how Suisun City’s zoning code treats historic resources, local historic designation, and the review rules that apply when you alter, demolish, or add to structures in historic areas. Key policy lives in the Waterfront District Specific Plan and the Architectural Review Board chapters of Suisun City's Title 18 (Zoning); site plan / architectural review, ADU exceptions, solar-on-historic rules, and SB 9 carve-outs also interact with preservation rules. See the sections cited below for the precise legal language and to confirm parcel-specific applicability. Verify with the jurisdiction for parcel-level status and map boundaries.

Where preservation rules live (short guide to the ordinance)

The city’s zoning regulations are in Title 18 - ZONING; the list of zoning districts (including DWSP, RL, RM, RH1, RH2, RMU, CR, CMU, APS, PQP) is in § 18.06.010 . Link: Suisun City zoning & planning overview and Suisun City Zoning.
Waterfront-specific preservation policy and the Architectural Review Board (ARB) appear in Chapter 18.78 (notably § 18.78.010, § 18.78.015, § 18.78.020, § 18.78.030) and tie preservation to the DWSP. These are the controlling local preservation provisions .
Site plan and architectural review rules that trigger design scrutiny across multiple zones are in Chapter 18.76 (e.g., § 18.76.030–.050) ; see Suisun City Design Review and Suisun City Development Standards.
Accessory dwelling (ADU) rules include explicit treatment of historic districts and ministerial exceptions in § 18.30.170; ADU parking and ministerial rules reference historic districts (ADU rules may treat historic areas differently) . Link: Suisun City ADUs.
Solar on historic buildings is addressed in § 18.60.090 (standards to avoid altering character-defining features) .
SB 9 ministerial urban-lot-split projects are explicitly barred on parcels located within a historic district or city landmark by § 18.08.080 (historic-district exclusion) .
Variances and appeals (including local variance authority relevant to historic properties) are handled under Chapter 18.80 (e.g., § 18.80.010–.020) .
Where state-level building-code treatment for historic buildings is referenced, the ordinance expects use of the state Historical Building Code where appropriate; see § 18.78.030 (local register / CHBC eligibility) . Link: California Building Standards Code.

District-by-district breakdown (preservation-relevant districts)

DWSP — Waterfront District Specific Plan (Waterfront)

Purpose: Explicit preservation objective — the ARB and the DWSP are intended to "recognize the interdependence of land values, preservation of historic structures and aesthetics" and to preserve historic structures in the DWSP area § 18.78.010 .
Typical review process: The Planning Commission serves as the Architectural Review Board (ARB) for applications in the DWSP; the ARB reviews alterations, additions, demolitions, removals, and signs within the DWSP, and may approve, modify, or disapprove (or forward advisory recommendations to council where required) § 18.78.015–.020 .
Key standards and where it applies: The ARB maintains and updates the city's local register of historic properties, recommends additions/deletions to the local register, and requires work on listed properties be undertaken "in accordance with the design criteria established by the waterfront district specific plan" § 18.78.020.B and § 18.78.030 . The ARB's authority inside the DWSP is tied to Chapter 18.26 (DWSP design criteria) as incorporated by the ARB chapter § 18.78.020.A . (Text of Chapter 18.26 itself was referenced but not reproduced in the retrieved materials; Verify with the jurisdiction.)
Practical guidance: If your property is in the DWSP, expect ARB review for exterior work, and prepare DWSP-specific design statements and elevations tied to the waterfront design criteria. See Suisun City Design Review.

RM, RH1, RH2, RMU — Medium/High density residential and Residential Mixed-Use

Purpose: Standard residential and mixed-use zones; preservation requirements are not unique to these zones but site plan and architectural review may apply to projects that alter building exteriors or are non-minor § 18.76.030–.050 .
Typical permitted uses: Residential, multi-family, and mixed-use as listed in the use tables (see Table references in Title 18) .
Dimensional standards (decision-relevant examples): setbacks, maximum heights, and lot coverage tables apply by zone (see Tables 18.31.01 and 18.33.01 for specifics) — e.g., RM recommended usable open space standards are in § 18.31.010 .
How preservation triggers operate: Projects that require site plan and architectural review (per § 18.76.030) must show elevations, materials, landscaping, parking layout, and exterior lighting; when the work affects a property that is already on the local register or within a designated historic district, review will emphasize preservation of character-defining features § 18.76.030–.040 . ADU ministerial approvals note exceptions where properties are in an "architecturally and historically significant historic district" — see § 18.30.170 O for ADU parking and ministerial language . Link: Suisun City ADUs and Suisun City Parking.

APS, CR, CMU, PQP and other non-residential zones

Purpose and uses: Civic, commercial, agricultural production, and public/quasi-public functions are governed by the district tables in Title 18 § 18.06.010 and specific development standards in Chapters 18.28–18.33 .
Preservation relevance: Where historic structures are located in these districts, Chapter 18.76 site plan and architectural review may apply; the DWSP rules may also overlay waterfront parcels in commercial designations. SB 9 and ministerial projects are explicitly prevented on parcels designated as historic or within a city landmark/district § 18.08.080 . Link: Suisun City Overlay Districts.

Quick reference table — decision‑relevant rules and who enforces them

Topic	What the code requires / effect	Code reference
Local register / eligibility for State Historic Code	Establishes a Local Register and states listed structures may be eligible as "qualified historic building" for state Historical Building Code treatment; work on certified properties must follow DWSP design criteria where applicable	§ 18.78.030
Who does design review in DWSP	Planning Commission serves as ARB; ARB reviews alterations, demolitions, signs in DWSP; can delegate administrative approvals	§ 18.78.015–.020
Site plan & architectural review triggers	Projects subject to site plan/architecture review must submit site plan, elevations, parking, landscaping; major projects go to Planning Commission; director handles administrative review	§ 18.76.030–.050
ADU exceptions / historic areas	ADU parking exceptions and ministerial treatment note properties inside an "architecturally and historically significant historic district" — ADU rules require recordation and ministerial timelines	§ 18.30.170 (O, R)
Solar on historic buildings	Solar allowed where it does not alter character-defining features; examples of acceptable siting (not visible from R.O.W., behind parapet, BIPV) are listed	§ 18.60.090
SB 9 exclusion for historic property	Two-unit SB 9 projects are not permitted on parcels located within a historic district or designated as city landmark/historic property	§ 18.08.080
Variance authority	Director may grant variances subject to findings and appeal; variances require specific findings showing special circumstances	§ 18.80.010–.020

Checklist — what an applicant must prepare for a preservation‑sensitive project

Confirm parcel status: Is the property on the Local Register or inside the DWSP or other historic district? Check with Development Services (local register maintained via ARB updates) § 18.78.020.B . Verify with the jurisdiction.
Determine review path: Does the project trigger site plan & architectural review (submit per § 18.76.030)? Prepare required materials (site plan, elevations, materials, parking layout, landscape, lighting) . Link: Suisun City Design Review and Suisun City Development Standards.
If in DWSP, prepare a DWSP design narrative tied to the waterfront design criteria; expect ARB review (§ 18.78.015–.020) .
For ADUs: if you propose an ADU, confirm ADU ministerial criteria and parking exceptions if in a historic district; record required deed restriction before final occupancy § 18.30.170 . Link: Suisun City ADUs and Suisun City Parking.
If solar is proposed on a historic building, document siting to avoid altering character-defining features (use § 18.60.090 standards) .
If relief is needed (setback/height), prepare variance findings per § 18.80.020 and anticipate public notice/hearing § 18.80.040–.050 .
Coordinate with building division early if you intend to claim Historical Building Code treatment (local register eligibility language in § 18.78.030) . Link: California Building Standards Code.

Risks & Ambiguities

Issue	Why it matters	What to verify
Is the parcel actually on the Local Register?	Local-register status changes review path (eligibility for CHBC and greater preservation scrutiny)	Verify listing with Development Services / ARB and check local register updates § 18.78.020–.030
DWSP design criteria text	The ARB requires work in DWSP to follow DWSP design criteria, but Chapter 18.26 text (the DWSP-specific design criteria) was referenced, not fully reproduced in retrieved materials	Confirm and obtain the DWSP / Chapter 18.26 design guidelines from the city (not found in retrieved materials) § 18.78.020.A
Whether proposed changes are "alterations" triggering ARB	Minor vs. major distinctions affect review timeline and appeal rights	Ask Development Services whether the proposal is administrative vs. ARB/planning-commission level under § 18.76.050
ADU parking and ministerial timeline in historic areas	ADU ministerial approval has exceptions for historic districts but requirements are fact-specific (recordation, one-space rules, etc.)	Confirm ADU ministerial criteria and parking exceptions for historic districts under § 18.30.170
SB 9 eligibility if near historic resources	SB 9 ministerial rights are precluded on historic parcels; an incorrect assumption can result in denial	Confirm SB 9 exclusions: § 18.08.080 disallows SB 9 where parcel is in a historic district or designated as a local landmark
Use of the State Historical Building Code	Local register listing can open CHBC relief, but qualification must be confirmed and CHBC application coordinated with building official	Verify CHBC eligibility and the building official’s process; local code anticipates CHBC applicability for listed properties § 18.78.030

Plain-English Summary

If your project affects a building in Suisun City’s Waterfront District or a property listed as a local historic resource, expect Architectural Review Board scrutiny and mandatory design compliance with the Waterfront District Specific Plan; ADU and solar rules contain special provisions for historic areas, and SB 9 lot-split ministerial rights are not available for properties inside historic districts. See the cited ordinance sections and check with Development Services for parcel-level status and the DWSP design criteria.

Source References

Title 18 - Zoning, Table of Zoning Districts and general rules § 18.06.010 . Source (municipal code print export): library.municode.com.
Architectural Review Board / Waterfront District Specific Plan — § 18.78.010, § 18.78.015, § 18.78.020, § 18.78.030 .
Site Plan & Architectural Review — § 18.76.030, § 18.76.040, § 18.76.050 .
Accessory Dwelling Units (ADUs) — § 18.30.170 (ADU ministerial/parking/historic references) .
Solar on Historic Buildings — § 18.60.090 .
SB 9 two‑unit projects historic exclusion — § 18.08.080 .
Variances — § 18.80.010, § 18.80.020, public notice/hearing rules § 18.80.040–.050 .
Suisun City zoning & planning overview: /us/california/suisun-city (internal GoCodebook link). Link: Suisun City Zoning.
Suisun City Design Review: /us/california/suisun-city/design-review; Suisun City Development Standards: /us/california/suisun-city/development-standards; Suisun City ADUs: /us/california/suisun-city/adu; Suisun City Parking: /us/california/suisun-city/parking; Suisun City Overlay Districts: /us/california/suisun-city/overlay-districts; California Building Standards Code: /us/california/building-codes.

Sources

Retrieved passages

Suisun City Zoning Code (§ 3) High relevance
CBC § 3 (§ 3) High relevance
CBC § 3 (§ 3) Medium relevance
Suisun City Zoning Code (Section 18.76.050.) Medium relevance
Suisun City Zoning Code (§ 65915) Medium relevance
CBC § 18955 (Section 18955) Medium relevance
Suisun City Zoning Code (§ 3) Medium relevance
Suisun City Zoning Code (§ 3) Medium relevance
CBC § 1612.1 (Section 1612.1) Medium relevance
CBC § G106 (SECTION G106) Medium relevance
CBC § 7060 (Section 7060) Medium relevance
Suisun City Zoning Code (§ 3) Medium relevance
Suisun City Zoning Code (Section 21155) Medium relevance
Suisun City Zoning Code (Chapter 18.42) Medium relevance

Cited sections

Official Suisun City code library

Frequently asked questions

What triggers architectural review in Suisun City?

Most projects that change site layout, building exteriors, parking, landscaping, or signs must go through site plan and architectural review; the submission requirements and review criteria are in § 18.76.030–.040 and the review authority is spelled out in § 18.76.050 .

Who acts as the Architectural Review Board for the Waterfront area?

The Planning Commission serves as the Architectural Review Board (ARB) for the Waterfront District Specific Plan (DWSP); the ARB reviews additions, alterations, demolitions, and signs within the DWSP per § 18.78.015–.020 .

If my house is on the city’s local register, can I use the State Historical Building Code?

The ordinance states local-register listing is intended to make structures eligible as "qualified historic buildings" for the state Historical Building Code, but you must confirm eligibility and coordinate with the building official; see § 18.78.030 .

Can I build an ADU on a property in a historic district?

ADUs are allowed but the ADU rules include specific ministerial exceptions and parking provisions where the property is in an "architecturally and historically significant historic district"; see the ADU rules at § 18.30.170 for the recordation, parking, and ministerial approval details .

Does the city allow rooftop solar on historic buildings?

Yes, but installations on historic buildings must not alter character-defining features. The code lists siting options (e.g., not visible from the public right-of-way, behind parapet, or building-integrated solar) in § 18.60.090 .

Can I use SB 9 ministerial lot-split rights on a historic parcel?

No; the two-unit SB 9 ministerial process is not allowed on parcels located within a historic district or designated/listed as a city landmark or historic property by local ordinance § 18.08.080 .

If I need a dimensional variance to preserve a historic façade, how does that work?

Variances are possible under local variance rules, but the director/planning commission must make the required findings; use the variance procedures in Chapter 18.80 (§ 18.80.010–.020) and expect public notice/hearing requirements § 18.80.040–.050 .

Where are the Waterfront District design criteria I must follow?

The ARB requires work on local-register properties in the DWSP to follow the design criteria established by the Waterfront District Specific Plan; the ARB chapter references Chapter 18.26 as the implementing design text (see § 18.78.020.A and § 18.78.030). The explicit DWSP/Chapter 18.26 text was referenced but was not reproduced in the retrieved materials — verify with Development Services and request Chapter 18.26/DWSP design guidelines .

Who updates the city’s local register of historic properties?

The ARB is charged with updating the survey and inventory that comprise the local register and makes annual recommendations to the City Council for certification; see § 18.78.020.B .

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