Local zoning · Ceres

Ceres — Overlay Districts

Q: What does the Airport Overlay (A‑O) do to building height limits in Ceres?

The A‑O overlay imposes approach‑surface and overlay height limits that can be more restrictive than the base zone; the ordinance requires that no structure or tree exceed the applicable overlay height surfaces shown in the airport approach plan. Verify the exact approach surface that applies to your parcel because the overlay ties to the Modesto City‑County Airport Approach and Clear Zone Plan. § 18.21.010–.020 .

Q: If my site is on the RHNA Overlay list, can I build by‑right?

If your site appears in Table 18.43.020‑1 , you may be eligible for by‑right development only if the project provides at least 20% of units deed‑restricted for low‑ and very‑low income households; the ordinance then removes certain discretionary approvals (e.g., CUP, PUD, discretionary design review) for that project. Confirm the site is on the table and document the deed‑restriction mechanism. § 18.43.020–.030 .

Overlay Districts under the Ceres local zoning and planning code, with the controlling citations.

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Last reviewed: July 1, 2026

Overview

Overlay districts in Ceres are special zoning layers that sit on top of base zones to add or modify development rules for defined areas. The Ceres Municipal Code adopts several overlays by reference (for example, a downtown specific plan), applies airport-related height and safety limits in an A‑O overlay, and establishes a Regional Housing Needs Assessment (RHNA) Overlay that creates by‑right development for qualifying affordable housing projects. See the controlling ordinance text at § 18.36.010, § 18.21.010–.020, and § 18.43.010–.030 for each overlay respectively.

How to read this page

This page covers only what the Ceres zoning code itself says about overlay districts. It does not discuss building code requirements (Title 24) — see the California Building Standards Code for construction regulations — or state housing law except where the Ceres code explicitly cites those requirements. For related local topics referenced in the text, see the City menu pages for development standards, parking, design review, ADUs, and nonconforming uses.

Overlay districts in the Ceres code — district-by-district

Below are the overlays adopted in Title 18 that are explicitly described in the retrieved ordinance file(s). Each subsection lists the purpose, what the ordinance says about typical permitted uses or changes, key dimensional or procedural standards, and where it applies / how its boundaries are defined.

A. A‑O — Airport Overlay Zone

Purpose: The A‑O overlay exists to add property development standards to parcels that lie in the Modesto City‑County Airport approach, transitional, horizontal, and conical zones; its purpose is to prevent hazards to airport users and surrounding properties. § 18.21.010.
Typical effect on uses: The overlay does not create a new base list of permitted uses; instead it imposes additional limitations (most notably height and vegetation/structure clearance) on top of whatever base zone the property is in. § 18.21.010–.020.
Key dimensional standards and controls:
- Height limits and slope surfaces are prescribed for the different airport approach zones; for example, the utility runway visual approach zone establishes a slope limit described in the ordinance language. § 18.21.020.A.
- The chapter treats trees and structures the same as “structures” for the purpose of maximum allowable height in the overlay area. § 18.21.020.
- Where the A‑O imposes a more restrictive height standard than the base zone, the overlay controls (i.e., it limits height further than the base zone). § 18.21.010.
Where it applies / map: The overlay boundaries are those shown on the Modesto City‑County Airport Approach and Clear Zone Plan and may be included in the Stanislaus County Airport Land Use Compatibility Plan. The Ceres ordinance cross‑references that mapping for the overlay area. § 18.21.010.
Practical note: Always check the overlay map when evaluating height, tree planting, antenna, or tower placements; the overlay can reduce allowable height even where a base zone would allow taller construction. Verify with the jurisdiction for parcel‑specific limits.

B. Downtown Specific Plan Overlay Zone (DSP Overlay)

Purpose: The ordinance adopts the city’s Downtown Specific Plan document as an overlay zone to the underlying zoning in the downtown area; the specific plan provides land‑use policies, regulations, and design guidelines for properties inside the DSP boundary. § 18.36.010.
Typical effect on uses: The Downtown Specific Plan supersedes the base zoning where there is a conflict — the code explicitly states that the specific plan controls to the extent of any inconsistency with Title 18. § 18.36.010.
Key dimensional standards and controls:
- The DSP is adopted by reference (the plan dated January 10, 2010, with Appendix A is maintained at the City Clerk), and its maps, allowed uses, and development standards are found in that document rather than repeated in the ordinance text. § 18.36.010.
Where it applies / map: Applies to all parcels inside the downtown specific plan boundaries; the ordinance requires the specific plan document be maintained in the Office of the City Clerk. § 18.36.010.
Practical note: For precise permitted uses, parking, and setbacks within the DSP, consult the Downtown Specific Plan document itself (adopted by reference in § 18.36.010) and confirm whether there are any local design review requirements under the plan.

C. Regional Housing Needs Assessment (RHNA) Overlay District

Purpose: The RHNA Overlay was created to facilitate development of affordable housing on certain previously‑identified housing inventory sites. § 18.43.010.
Applicability and where it applies: The overlay is applicable only to those sites listed in the ordinance table (Table 18.43.020‑1). The table lists specific APNs and the zoning designation for each identified site (e.g., PC‑43, PC‑47). § 18.43.020.
Key procedural standard (by‑right development):
- Projects that provide at least 20% of total units deed‑restricted for low‑ and very‑low income households are eligible for by‑right development within this overlay. § 18.43.010–.030.
- The ordinance defines what “by‑right” removes: no Conditional Use Permit, no Planned Unit Development permit, no discretionary design review other than objective standards, and no other discretionary approvals that would trigger CEQA project review (per the ordinance’s list). § 18.43.030.
Practical note: The RHNA Overlay is site‑specific — check Table 18.43.020‑1 to see whether a parcel is on the list. If it is, conforming affordable projects meeting the 20% deed restriction threshold can use the by‑right pathway described in § 18.43.030.

Quick reference table — decision‑relevant overlay rules

Overlay District	Decision‑relevant standard or effect	Code reference
A‑O (Airport Overlay Zone)	Adds airport approach height limits and prohibits structures/trees exceeding overlay surfaces; overlay controls when more restrictive than base zone	§ 18.21.010–.020
Downtown Specific Plan Overlay	Downtown Specific Plan adopted by reference; where plan conflicts with Title 18, the specific plan controls; plan document held at City Clerk	§ 18.36.010
RHNA Overlay	Sites listed in Table 18.43.020‑1; projects with ≥20% low/very‑low deed‑restricted units are eligible for by‑right development (waives several discretionary approvals)	§ 18.43.010–.030

Practical guidance & synthesis

Overlay vs base zone: An overlay does not replace the underlying base zoning district (for example, C‑2, M‑2, P‑C). Instead, it adds or modifies rules that apply inside the overlay area; when an overlay is more restrictive, the overlay controls (for instance, A‑O height limits override base zone height where applicable). § 18.21.010.
Document adoption by reference: The Downtown overlay is implemented by adopting an external plan as an overlay; that means many of the downtown area’s permitted uses, design controls, and development standards live in the specific plan document rather than repeated in Title 18. § 18.36.010.
Fast‑track path for affordable housing: The RHNA Overlay creates a specific, limited by‑right path for qualifying projects (20% deed‑restricted affordable). If you can meet that threshold, several discretionary reviews are removed — but you still must meet objective development standards and other non‑zoning obligations. § 18.43.030.
Cross‑checks you will need: check parking and access rules (see parking), development setback and lot standards (see development standards), and whether design review or objective standards apply (see design review). If the parcel is in the A‑O, check airport approach maps referenced in § 18.21.010 for height constraints.

Checklist — what an applicant must do for a parcel in an overlay

Confirm whether the parcel lies inside any overlay: A‑O, Downtown Specific Plan, or RHNA Overlay (check City maps and Table 18.43.020‑1). § 18.36.010, § 18.21.010, § 18.43.020.
For parcels in the A‑O, calculate maximum allowable structure height against the overlay surfaces; revise design to meet the overlay slope/height limits. § 18.21.020.
For parcels inside the Downtown Specific Plan Overlay, obtain and follow the Downtown Specific Plan document for permitted uses, design guidance, and development standards; check for any design review triggers. § 18.36.010.
For parcels listed in Table 18.43.020‑1, confirm whether your project can meet the 20% deed‑restricted affordable threshold to qualify for the by‑right pathway; if so, document deed‑restriction mechanism and prepare for ministerial approvals as applicable. § 18.43.010–.030.
Check related standards that overlays do not displace — e.g., setbacks, lot coverage, parking requirements — by consulting the development standards and parking rules.
Coordinate any airport‑related exceptions or variances early with Community Development for A‑O parcels (verify if any federal/County airport compatibility plan reviews are required per § 18.21.010). § 18.21.010.

Risks & Ambiguities

Issue	Why it matters	What to verify
Parcel boundary vs overlay map	Overlay rules only apply inside the mapped overlay; an error in boundary interpretation changes what controls apply	Verify parcel inclusion with City zoning map/Planning Division and the specific plan map (DSP) or Table 18.43.020‑1. § 18.36.010, § 18.43.020.
Specific plan details not restated in Title 18	The Downtown Specific Plan contains the operative use table and design standards — Title 18 only adopts it by reference	Request the downtown specific plan document from City Clerk and confirm which plan provisions control development. § 18.36.010.
Exact overlay height geometry and tree/vegetation rules	Airport overlay uses map and approach surface geometry to set height — wording in code references the Modesto plan and Stanislaus County ALUCP	Confirm the exact overlay surface and any County coordination requirements; measure project elements against the A‑O surfaces. § 18.21.010–.020.
Eligibility for RHNA by‑right treatment	The ordinance limits by‑right to the sites listed and requires 20% low/very‑low deed restrictions — administrative interpretation may be needed on deed‑restriction timing and form	Verify the required deed restriction form, recorded covenant language, and whether design/construction documents meet “objective” standards waived from discretionary review. § 18.43.010–.030.
Conflicts between overlay and base zone	Overlays can be more restrictive (e.g., A‑O height) or provide alternative procedures (RHNA by‑right)	When in doubt, list both the base zone standard and the overlay standard and verify which applies per the controlling code text: overlays control to the extent they conflict. § 18.21.010, § 18.36.010.

Plain‑English summary

Ceres uses overlays to add location‑specific rules: the A‑O (Airport Overlay) limits height and trees near the Modesto airport (check height surfaces), the Downtown Specific Plan Overlay replaces certain zoning rules inside downtown with rules in the adopted downtown plan, and the RHNA Overlay allows specific listed sites to get a by‑right approval if the project sets aside 20% of units as low/very‑low income. Always confirm overlay boundaries for your parcel and follow the overlay chapter cited in the code: § 18.21, § 18.36, and § 18.43.

Source References

Ceres Municipal Code, Title 18 — A‑O, Airport Overlay Zone, § 18.21.010–.020.
Ceres Municipal Code, Title 18 — Downtown Specific Plan Overlay Zone, § 18.36.010.
Ceres Municipal Code, Title 18 — Regional Housing Needs Assessment Overlay District, § 18.43.010–.030 (including Table 18.43.020‑1 listing applicable sites).
Ceres Municipal Code, Title 18 — general procedural chapters on Planning responsibilities and by‑right implementation references used in the RHNA chapter. § 18.03.010–.050 and § 18.43.030.

Sources

Retrieved passages

CBC § 1 (section 18.35.150) Medium relevance
Ceres Zoning Code (chapter 5.15) Medium relevance
Ceres Zoning Code (§ 1) Medium relevance
Ceres Zoning Code (§ 1) Medium relevance
Ceres Zoning Code Medium relevance
Ceres Zoning Code (§ 1) Medium relevance
Ceres Zoning Code (section 5.22.020) Medium relevance
Ceres Zoning Code (§ 1) Medium relevance

Cited sections

Official Ceres code library

Frequently asked questions

What does the Airport Overlay (A‑O) do to building height limits in Ceres?

The A‑O overlay imposes approach‑surface and overlay height limits that can be more restrictive than the base zone; the ordinance requires that no structure or tree exceed the applicable overlay height surfaces shown in the airport approach plan. Verify the exact approach surface that applies to your parcel because the overlay ties to the Modesto City‑County Airport Approach and Clear Zone Plan. § 18.21.010–.020.

Where can I find the rules that apply inside Ceres’s downtown overlay?

The downtown overlay is implemented by adopting the Downtown Specific Plan document by reference; the Ceres zoning code states the plan (dated January 10, 2010, with Appendix A) controls where it conflicts with Title 18 and that a copy is maintained at the City Clerk. For permitted uses and design controls, consult that plan. § 18.36.010.

If my site is on the RHNA Overlay list, can I build by‑right?

If your site appears in Table 18.43.020‑1, you may be eligible for by‑right development only if the project provides at least 20% of units deed‑restricted for low‑ and very‑low income households; the ordinance then removes certain discretionary approvals (e.g., CUP, PUD, discretionary design review) for that project. Confirm the site is on the table and document the deed‑restriction mechanism. § 18.43.020–.030.

Do overlays change parking or setback rules in Ceres?

Overlays can modify or supersede base zoning standards, but whether parking or setbacks change depends on the overlay language. For example, the Downtown Specific Plan controls downtown specifics by reference and may specify different parking/setback rules; the A‑O focuses on height/airspace, not parking. Always check the overlay chapter and the applicable plan. § 18.36.010, § 18.21.010.

How do I confirm whether my parcel is inside an overlay district in Ceres?

Confirm parcel overlay status with the City’s planning/zoning map or by asking the Planning Division; the DSP is mapped in the Downtown Specific Plan and the RHNA Overlay sites are listed in Table 18.43.020‑1 of the code. If maps aren’t conclusive, request an administrative determination from the Director of Community Development. § 18.36.010, § 18.43.020, § 18.03.050.

What does “adopted by reference” mean for the Downtown Specific Plan overlay?

“Adopted by reference” means the Downtown Specific Plan document itself contains the detailed rules and is legally part of the zoning regulations; where the plan’s provisions conflict with Title 18, the plan controls in the DSP area. The Ceres code directs you to the specific plan document maintained at the City Clerk. § 18.36.010.

Are there any overlays in Ceres that remove discretionary review?

Yes — the RHNA Overlay provides a narrowly tailored by‑right pathway that removes several discretionary reviews (Conditional Use Permit, Planned Unit Development, discretionary design review, and other discretionary approvals constituting a CEQA “project”) for qualifying projects meeting the 20% deed‑restriction requirement. § 18.43.030.

How does the A‑O overlay interact with County or regional airport plans?

The A‑O in Ceres references the Modesto City‑County Airport Approach and Clear Zone Plan and may be consistent with the Stanislaus County Airport Land Use Compatibility Plan; the ordinance ties the overlay’s mapping and standards to those airport planning documents. Confirm whether County ALUCP review or coordination is required for your project. § 18.21.010.

Do I still need to follow development standards like setbacks and parking if an overlay applies?

Yes. Overlays supplement or modify base zone rules — they do not generally eliminate basic development standards such as setbacks, lot coverage, or parking unless the overlay or an adopted specific plan explicitly provides alternatives. Always cross‑check the overlay chapter against the development standards and parking requirements. § 18.36.010, § 18.21.010.

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