Local zoning · San Ramon

San Ramon — Nonconforming Uses

Q: If my nonconforming building was 60% destroyed in a fire, can I rebuild it as it was?

No — if involuntary damage exceeds 50% of the structure’s current market value, the structure cannot be reconstructed or restored in its nonconforming form except in conformity with the current zone regulations; if damage is ≤50% , reconstruction is allowed if restoration is initiated within 180 days and substantially completed within 12 months. § D7-3.B.1–2

Q: Who decides whether a proposed new use is “similar” to an existing listed use?

The Zoning Administrator can determine that an unlisted proposed use is similar/compatible to a listed use after making specified findings; that determination must be in writing and may be referred to the Commission or appealed. § D2‑2 (use determination procedures) and related administrative provisions apply.

Nonconforming Uses under the San Ramon local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

This page explains how San Ramon’s Zoning Ordinance treats nonconforming uses, structures, and parcels — what can continue, when nonconforming rights end, what repairs or expansions are allowed, and special exemptions. The controlling rules are in Chapter I of Division D7 (Nonconforming Uses, Structures, and Parcels) of the San Ramon Zoning Ordinance (the local Unified Development framework); key procedural cross‑references include Minor Use Permits and other Division D6 procedures. See the ordinance definitions and program structure in § D7-1 through § D7-6 for the controlling language.

What the code says (high‑level)

A nonconforming use or structure that was lawful when established can continue but is subject to rules limiting enlargement, repair, and abandonment; the ordinance's purpose is to discourage permanence of nonconformities while allowing limited continuation. See § D7-1.
A nonconforming use may be changed only to another nonconforming use that is similar or more restricted and may not be intensified without city approval; enlargement of a nonconforming land use (no structure) is prohibited. See § D7-2.
Repairs and rebuilding of nonconforming structures after damage are allowed only within defined limits (50% rule) and otherwise must conform to current zone standards; ordinary maintenance is allowed with limits. See § D7-3.
A parcel that is substandard relative to current zone area/width/depth rules can be treated as a legal building site if it meets established historical/record criteria; splits or lot line adjustments that increase nonconformity are prohibited. See § D7-4.
Exemptions apply (historic resources, single‑family height only nonconformance, certain accessory structures, and replacement rules for involuntarily damaged dwellings). See § D7-5.
Unlawful structures/uses (those established in violation of law) are not “nonconforming” and receive no protection under this Chapter. See § D7-1.D.

District‑by‑district notes (where the nonconforming rules apply)

The Nonconforming Chapter (Division D7, Chapter I) applies across San Ramon’s zoning districts; the ordinance organizes allowable uses and development standards in Division D2 and site/development standards in Division D3. For many district identifiers and mixed‑use zone types the code gives specific names; where the Local Code provides zone‑specific development standards those standards interact with the nonconforming rules described above. The code contains a zoning district key that includes, among others, AG, OS‑1/OS‑2, P, RM / RMH / RH, RC / RE / RS (residential categories), MUX / MUR / DMU‑N / DMU‑S / CCMU (mixed‑use variations), and commercial/industrial categories such as GC, CT, CC, M‑1 / M‑2. See the zoning symbol key and Mixed‑Use development standards.

Note: the chapter D7 rules themselves are zone‑neutral; they limit or allow nonconforming continuation and repair regardless of which zone the property sits in. Zone‑specific dimensional standards (setbacks, FAR, lot coverage, etc.) appear elsewhere in Division D2 and Division D3 and must be consulted when the nonconforming rules require conformance with the “subject zone.” Below are district‑level practical summaries using the actual zone codes that appear in the San Ramon Ordinance.

AG (Agriculture)

Purpose: preserve agricultural uses and open land. See Division D2 allowable‑uses tables.
Typical permitted uses: crop production, grazing, limited agricultural processing (per Division D2 tables).
Nonconforming guidance: agricultural uses that became nonconforming upon rezoning may continue under § D7-2 but cannot be enlarged in area or intensity if they are nonconforming land uses.
Key numeric AG development standards (setbacks, lot size) — Not found in retrieved materials; consult Division D2 zone tables and the Zoning Map to confirm parcel‑specific limits. Verify with the jurisdiction.

OS‑1 / OS‑2 (Open Space)

Purpose: protect parks, creeks, ridgelines and open areas. See Division D2 and the Zoning Map.
Uses permitted and special rules appear in Division D2 tables; nonconforming open‑space uses follow general Chapter D7 rules (e.g., discontinuance rule, no enlargement of nonconforming land uses). § D7-2 applies.

P (Public)

Purpose: public facilities; many utility structures are specifically exempted from the Chapter’s removal/reconstruction limits when they serve the utility function. See § D7-5.I for public utility exceptions.

Residential zones (examples in code: RS / RE / RC / HR / RM / RMH / RH)

Purpose: single‑ and multi‑family housing types; definitions of Multi‑Family and single‑family are in the glossary.
Typical permitted uses: single‑family dwellings, multi‑family housing, accessory dwelling units (ADUs) (ADUs are explicitly included in the land‑use tables as permitted in many zones).
Nonconforming structure repair and rebuild: single‑family and multi‑family dwellings have an explicit exception allowing replacement using the same development standards after involuntary destruction (subject to documentation and time limits). See § D7-5.D.

Mixed‑Use zones (MUX, MUR, DMU‑N, DMU‑S, CCMU)

Purpose and standards: mixed‑use development standards (daylight plane, minimum lot/ density rules determined via subdivision or land‑use review) are in § D2‑14 / § D2‑15; these development standards are referenced when a nonconforming structure or use seeks to rebuild or expand.
Nonconforming implications: expansions of nonconforming uses that would increase nonconformity require a Minor Use Permit (see D7 and D6 cross‑references). See § D7-2 and § D6‑28.

Commercial & Industrial (GC, CC, CT, CR, M‑1, M‑2)

Purpose: retail, office, commerce and manufacturing. Nonconforming uses in these zones follow the same limitations: transfers and continued operation may be allowed but enlargement and intensification are restricted and, for structural changes beyond repair thresholds, reconstruction must comply with zone standards. See § D7-2 and § D7-3.

Key decision‑relevant rules (quick table)

What the applicant needs to know	Short rule	Code Reference
Can I enlarge a nonconforming land use (no structure)?	No — a nonconforming use of land (except accessory structures <400 sq ft) may not be enlarged, extended, or intensified.	§ D7-2.C.1
Can I expand a nonconforming use inside a structure?	Only via Minor Use Permit and only if it does not increase the degree/detrimental effects of nonconformity; Zoning Admin must make findings.	§ D7-2.C.2; § D6-28
What if the building is damaged/destroyed?	If involuntarily damaged ≤ 50% of market value → may be rebuilt if restoration initiated within 180 days and substantially complete within 12 months; if >50% → must conform to current zone.	§ D7-3.B.1–2
How long before nonconforming status is lost for discontinued uses?	Continuous discontinuance of 180 calendar days terminates legal nonconforming status.	§ D7-2.D.1–4
When is a nonconforming parcel a legal building site?	If it was created by recorded subdivision, by deed before the zoning change, resulted from a variance/lot line adjustment, or reduced by public acquisition within limits.	§ D7-4.A
Exemptions (historic, SF height, accessory setbacks)	Historic resources, SF height exceedances, and certain single‑family setback nonconformances are treated as exempt or given specific allowances.	§ D7-5.A–C

Practical guidance & cross‑references (plain‑English interpretation)

If your business/use was lawful before a zoning change and did not require a permit that it lacks today, you generally can keep operating — but you cannot expand the land area or materially increase intensity without city approval (Minor Use Permit) and findings showing no greater detrimental effect. See § D7-2.
For structural repair after damage: document market value and file a complete Building Permit promptly. If damage is ≤ 50% of market value, rebuild to the previous footprint/height if you start within 180 days and finish substantially within 12 months; if damage > 50%, new construction must meet current zone rules (so you may lose a nonconforming setback or height). See § D7-3.B.
When a nonconforming use is only lacking an historic Minor Use Permit or Use Permit that would now be required, the code treats the use as conforming only to its previous scope (hours, site area, etc.), not expanded beyond that historic benchmark. See § D7-2.G.
Be prepared for administrative determinations: the Zoning Administrator has authority to determine discontinuance, similarity to listed uses, and to accept documentation that makes a parcel a legal building site. Appeal paths are available via Division D7 Chapter II. See § D7-4, § D6-29 (variances), and related D6 procedures.
Consult the Division D2 use tables to determine whether a future proposed use is allowed in the zone, and whether a Use Permit, Zoning Clearance, or Minor Use Permit is required; those permit types interact with nonconforming status when changes or expansions are proposed. See Division D2 land‑use tables and permit keys.
Practical cross‑checks: check parking requirements (San Ramon sets zone‑specific parking and has buffers for R zones) — see Parking provisions and landscaping tables when proposing changes to uses that might affect off‑street parking or buffers. For review thresholds, see the procedural chapters on design review, variances, and permits. Link to those departments/pages as you plan an application: San Ramon Parking, Design Review, Development Standards, Overlay Districts, and Variances and Exceptions.

Checklist (what the applicant must satisfy before proposing changes)

Establish whether the current use/structure was lawful when established (collect permits, dated receipts, deeds). See § D7-1.
Determine if the use has been discontinued for ≥180 days (if yes, nonconforming rights terminated). See § D7-2.D.
If proposing expansion of a nonconforming use within a structure, prepare a Minor Use Permit application and show the expansion will not increase the degree or detrimental effects of the nonconformity. See § D7-2.C.2 and § D6-28.
If rebuilding after damage, obtain a licensed appraisal, file a Building Permit promptly (restoration initiated within 180 days if ≤50% damage), and verify whether reconstruction must meet current zone standards (if >50% damage). See § D7-3.
Verify whether your parcel qualifies as a legal building site under § D7-4 (recorded subdivision, deed date, variance/lot line adjustment, or partial govt acquisition).
If your property is an historic resource or in a Landmark District, document eligibility for the D7 historic exemptions and prepare a Minor Use Permit if proposing alteration. See § D7-5.A.

Risks & Ambiguities

Issue	Why it matters	What to verify
Has the nonconforming use been "discontinued"?	Continuous discontinuance ≥180 days terminates nonconforming rights; resuming use after that means you must comply with current zone rules.	Check records for utility disconnection, removal of equipment, tax/business filings; confirm with Zoning Administrator. § D7-2.D
Damage valuation (≤50% or >50%)	The 50% threshold determines whether you can rebuild to prior nonconforming form or must comply with current standards. Market value and timing rules apply.	Obtain licensed appraisal and confirm Building Official’s market value determination. § D7-3.B
"Similar or more restricted" replacement uses	Swapping to another nonconforming use is allowed only if it is similar or more restricted; otherwise it may be treated as a new nonconforming benchmark.	Provide use comparison, anticipated intensity, and show no increased detrimental impacts. § D7-2.B
Parcel legal‑building‑site status	Not all substandard parcels are legal building sites; misclassification risks permit denial.	Produce recorded subdivision/deed evidence or variance/lot line adjustment history. § D7-4.A
Interaction with other code chapters (ADU rules, State law)	State ADU law may limit local authority regarding nonconforming conditions for ADU permitting; San Ramon’s zoning tables treat ADUs as permitted in many zones.	For ADU‑specific nonconforming questions consult both San Ramon ADU rules (Division D2 and D4 references) and State ADU law. Verify with City staff. See § D2 tables and D4 ADU references.

Plain‑English Summary

If your use or building in San Ramon was lawful when it started, it can usually keep operating but you generally cannot expand it, and if you stop operating for 180 days you lose that protection; structural repairs after damage are allowed under a 50% rule and other exceptions for historic or single‑family properties exist. Check § D7‑1 through § D7‑5 for the exact rules and talk to the Zoning Administrator before you rebuild, expand, or change use.

Source References

San Ramon Zoning Ordinance — Division D7, Chapter I (Nonconforming Uses, Structures, and Parcels): § D7-1 through § D7-6.
Nonconforming Uses detailed (replacement, enlargement, discontinuance): § D7-2.
Nonconforming Structures (repair, 50% rule): § D7-3.
Nonconforming Parcels (legal building sites): § D7-4.
Exemptions (historic, single‑family height/setbacks): § D7-5.
Permit and procedural cross‑references, Minor Use Permit and Use Permit: § D6‑28, § D6‑29 (variances).
Division D2 allowable uses and zoning district keys (zone symbols and ADU references): Division D2 tables and Mixed‑Use standards (D2‑III / D2‑IV / D2‑V; § D2‑14 / § D2‑15).
Site standards and development rules referenced by nonconforming provisions: Division D3 (setbacks, fencing, landscaping, signage) — see D3 chapters and tables (e.g., § D3‑10, Table 3‑6, Table 3‑15).
San Ramon ADU and State ADU law summary (context for ADU permitting vs. nonconforming conditions): 2025 ADU handbook excerpt in the record.

Sources

Retrieved passages

San Ramon Zoning Code (Section D6-28.) High relevance
San Ramon Zoning Code (Chapter provides) High relevance
San Ramon Zoning Code (Section and) High relevance
San Ramon Zoning Code (Section D6-28) High relevance
San Ramon Zoning Code (Section D6-28) High relevance
San Ramon Zoning Code (Section D6-28) High relevance
San Ramon Zoning Code (Section D6-28) High relevance
San Ramon Zoning Code (Section D6-28) High relevance
CPC § 228 (Section shall) High relevance
San Ramon Zoning Code High relevance
CBC § 66321 (§ 66321) High relevance
CBC § 500 (Chapter I) Medium relevance
San Ramon Zoning Code (Section D2-4) Medium relevance
San Ramon Zoning Code (Chapter VII) Medium relevance
San Ramon Zoning Code (§ 6) Medium relevance
San Ramon Zoning Code (Section D6.28) Medium relevance
San Ramon Zoning Code Medium relevance
CBC § D6 (Section D6-16) Medium relevance

Cited sections

Official San Ramon code library

Frequently asked questions

How long can a nonconforming use sit idle before it loses protection?

If a nonconforming use is discontinued for a continuous period of 180 calendar days, the legal nonconforming status terminates and the use cannot resume as nonconforming; the Zoning Administrator will consider evidence like removed equipment or disconnected utilities in deciding. § D7-2.D

Can I expand my nonconforming business inside an existing building?

Potentially — an expansion of a nonconforming use within a structure may be allowed only through approval of a Minor Use Permit and only if the expansion does not increase the degree or the detrimental effects of the nonconformity; the Zoning Administrator must make the required findings. § D7-2.C.2; § D6-28

If my nonconforming building was 60% destroyed in a fire, can I rebuild it as it was?

No — if involuntary damage exceeds 50% of the structure’s current market value, the structure cannot be reconstructed or restored in its nonconforming form except in conformity with the current zone regulations; if damage is ≤50%, reconstruction is allowed if restoration is initiated within 180 days and substantially completed within 12 months. § D7-3.B.1–2

Does San Ramon treat historic nonconforming buildings differently?

Yes — historic structures listed or certified as historic resources (or included in a San Ramon Landmark District) may be altered or enlarged with Minor Use Permit approval without conforming to current setbacks, subject to criteria and authenticity requirements in § D7-5.A. § D7-5.A

What makes a substandard parcel a legal building site in San Ramon?

A nonconforming parcel is a legal building site if it was created by a recorded subdivision, by recorded deed before the zoning change, resulted from a variance or lot line adjustment, or was reduced by government acquisition within specified limits; the Zoning Administrator must be satisfied with the evidence. § D7-4.A

Can I change a nonconforming use to any different use?

No — you may change a nonconforming use only to another nonconforming use of a similar or more restricted classification or nature, and the replacement becomes the new benchmark; you cannot later change it to a less restricted classification. § D7-2.B

Are public utilities exempt from nonconforming reconstruction limits?

Yes — the ordinance states that public utility structures directly related to service distribution are not subject to the Chapter’s removal/reconstruction restrictions and may be modernized, expanded, or replaced to serve the utility. § D7-5.I

If I want to subdivide a nonconforming parcel, can I?

No — the code forbids subdivision or lot line adjustments that would increase the nonconformity of an existing parcel or any nonconforming use on the parcel. § D7-4.B

Are accessory dwelling units (ADUs) treated differently when parcels or structures are nonconforming?

San Ramon’s land‑use tables show ADUs as permitted in many residential zones, and State ADU law limits local agencies’ ability to deny ADU permits due to nonconforming zoning conditions in many circumstances; for ADU‑specific nonconforming questions consult both the San Ramon land‑use rules (Division D2 and D4) and State ADU provisions. See Division D2 tables and the ADU summary.

Who decides whether a proposed new use is “similar” to an existing listed use?

The Zoning Administrator can determine that an unlisted proposed use is similar/compatible to a listed use after making specified findings; that determination must be in writing and may be referred to the Commission or appealed. § D2‑2 (use determination procedures) and related administrative provisions apply.

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