Local zoning · Portola

Portola — Nonconforming Uses

Q: What is a “nonconforming use” in Portola?

A nonconforming use is a use that was lawful when established but no longer complies with current zoning rules because the zoning changed. The rules governing continuation, limits on enlargement, substitution, and loss of nonconforming status are in § 17.37.020 .

Q: How long before a nonconforming use is considered abandoned?

If a nonconforming use is discontinued for six months , it is deemed abandoned and the property must be used in compliance with current zoning rules going forward, per § 17.37.020(F) .

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

Ask a question free See coverage

Last reviewed: July 2, 2026

Overview

This page explains how the City of Portola regulates nonconforming uses, nonconforming structures, and nonconforming parcels under Title 17 (Zoning). It is strictly tied to the City code: how long a nonconforming use can continue, when expansions or substitutions are allowed, what happens after damage or abandonment, and the special rules for nonconforming parcels. See the City's zoning overview at Portola Zoning for the full map and district context.

Key rules & short summary table

The city’s controlling rules live in Chapter 17.37 (Nonconforming Uses, Structures and Parcels). The most decision-relevant rules are summarized below; each row identifies the controlling code citation.

Rule	What the rule lets/forbids	Code reference
Continuation but no enlargement of nonconforming uses	A lawful pre-existing nonconforming use may continue but cannot be enlarged or extended to occupy a larger area except where the chapter allows specific exceptions.	§ 17.37.020(B)
Residential use in commercial/industrial zones	A pre-existing residential building in a nonresidential district may remain residential but must meet R‑1 residential development standards (see § 17.16.030.A) until removed or converted.	§ 17.37.020(B)(1) and § 17.16.030.A
Expansion of nonresidential nonconforming uses in commercial/industrial zones	Allowed only with a Conditional Use Permit (CUP).	§ 17.37.020(B)(3)
Substitution of a nonconforming use	A different nonconforming use (equal or less intensive) may replace an existing nonconforming use only with a CUP and limited to the same area.	§ 17.37.020(B)(4)
Nonconforming structures — repairs/additions	Residential buildings nonconforming only for height/setback may be altered provided the alteration does not increase the nonconformity; nonresidential alters same, except nonresidential in residential zones is prohibited.	§ 17.37.020(C)
Nonconforming parking	You may reconstruct or alter a building with nonconforming parking so long as use does not expand and trigger additional parking requirements per the parking chapter.	§ 17.37.020(D) and § 17.40.030
Damage and destruction	If damage ≤50% (by building inspector valuation), may reconstruct without increasing nonconformity; if >50%, reconstruction rules differ for nonconforming use vs. nonconforming building (CUP or variance, with time limits). Floodplain restrictions also apply.	§ 17.37.020(E) and § 17.28.020
Abandonment	A nonconforming use that is discontinued for six months is deemed abandoned and loses legal nonconforming status (unless an alternative shorter period appears elsewhere).	§ 17.37.020(F)
Nonconforming parcels (undersized lots)	An existing parcel that fails current lot-size/frontage standards may be used as a building site only if it meets the proof criteria (approved subdivision or other standards in § 17.37.030).	§ 17.37.030

District-by-district breakdown

Below are the Portola zoning districts that most commonly host nonconforming issues. Each subsection gives the district purpose, typical permitted uses and the key dimensional/development standards where found in the code. Where the ordinance text in the uploaded materials did not list a numeric standard, I note that and point you to verify with the jurisdiction.

Note: first mentions include links to related pages — use those links for planning steps (parking, overlays, ADUs, design review, building code).

Residential zones (chapter 17.16) — Rural Residential (RR), LDR, MDR, HDR, and R‑1 reference

Purpose: The residential chapter establishes the residential districts to accommodate different housing types and densities; R‑1 standards are referenced for applying residential development rules to nonconforming residences in nonresidential zones.
Typical permitted uses: Single‑family dwellings, accessory residential uses, home occupations, and accessory dwelling units (ADUs) subject to 17.70; see the ADU rules at Portola ADUs.
Key dimensional standards: The code references § 17.16.030.A (R1 district) as the residential development standard used when an existing residence sits in a nonresidential zone (i.e., a nonconforming residential use may be continued subject to R‑1 standards). Exact numeric setbacks and lot-size fields for R‑1 were not included in the retrieved snippets — verify with the jurisdiction or the full Title 17 table. Not found in retrieved materials for numeric R‑1 table values; see § 17.16.030.A.
Where it applies: Citywide where parcels are mapped as residential per the official zoning map. For ADU interactions, note § 17.70.040(I): ADUs are permitted when the primary structure is nonconforming provided the ADU does not increase the nonconformity (link: Portola ADUs).

Commercial zones — CC, CMU, SC (chapter 17.19)

Purpose: Mixed commercial uses and services to support Portola’s commercial needs.
Typical permitted uses: Retail sales, personal and business services, offices, restaurants (uses vary by subdistrict: CC, CMU, SC — see the use table in Title 17). Example entries show Neighborhood Commercial, Personal Services, Offices as typical permitted types.
Key dimensional standards (from § 17.19.030): Min lot size: 3,125 sq ft; Min frontage: 25 ft; Front setback: 10 ft (CC/SC), 20 ft (CMU); side/rear setbacks vary by adjacency (none if adjacent to commercial/industrial; 10 ft if adjacent to noncommercial). See the commercial standards table for the exact per‑district cells. These numeric development standards are in § 17.19.030.
Nonconforming-use implications: A nonconforming nonresidential use in a commercial zone may be expanded or modified only with a CUP per § 17.37.020(B)(3); substitution also requires a CUP and must not increase the footprint.
Where it applies: Where land is mapped CC, CMU, or SC. If the parcel is in an overlay (e.g., OT Old Town or DC Downtown Core) overlay rules can modify parking or design expectations; see Portola Overlay Districts and Portola Design Review.

Industrial zone — BP/LI (chapter 17.22)

Purpose: Business park and light industrial uses.
Typical permitted uses: Light manufacturing, warehousing, equipment storage, certain vehicle services (some uses conditional). See the Title 17 use table for the full list.
Key dimensional standards (from § 17.22.030): Min lot size: 3,125 sq ft; Min frontage: 25 ft; Front setback: 10 ft (parking/landscaping may project); Site coverage: 60% without a Precise Plan; Height limit: 35 ft; side/rear setbacks vary based on adjacency.
Nonconforming-use implications: Nonresidential nonconforming uses in these zones may be expanded only with a CUP; residential uses present as nonconforming residences remain subject to R‑1 standards per § 17.37.020(B)(1).

Overlay and special-purpose zones — Old Town (OT), Downtown Core (DC), Floodplain (FP) (chapter 17.28)

Old Town (OT) and Downtown Core (DC) overlays: These overlays allow special rules for historic or narrow‑lot areas (modifying parking and design standards where the overlay applies). If a parcel is in an overlay, the overlay standards control where they conflict. For parking waivers or special design expectations see Portola Overlay Districts and Portola Parking.
Floodplain (FP): The FP overlay imposes strict additional limits. In particular, reconstruction after substantial damage that would relocate any portion of a reconstructed building into the floodplain is forbidden; certain reconstructions require CUPs or variances; and fill/excavation have heavy procedural and substantive limits. Always verify floodplain mapping before reconstruction — see § 17.28.020 for floodplain-specific reconstruction and permitted uses. FP rules can supersede nonconforming reconstruction allowances (e.g., no portion of reconstructed nonconforming use may be located within the floodplain).

Practical guidance & plain‑English synthesis (how the rules play out)

If you own or represent a property with a pre‑existing use that no longer fits the zone, you may typically continue that use — but you cannot enlarge it or occupy more area than before unless the code explicitly allows it (e.g., residential in a commercial zone follows R‑1 development standards). § 17.37.020(B) is the anchor rule.
Want to expand a nonconforming business in a commercial or industrial zone? Budget time and materials for a Conditional Use Permit. Expect to prove compatibility with the General Plan, applicable standards, and neighborhood compatibility findings (§ 17.88.060).
If the building is damaged: the city distinguishes ≤50% damage from >50% by value. ≤50% — reconstruction is allowed provided you do not increase the degree of nonconformity; >50% — different approvals (CUP or variance) and time limits to begin reconstruction apply. Check § 17.37.020(E) and floodplain rules if the parcel is in FP.
Nonconforming parking can remain, and you may reconstruct a building with nonconforming parking so long as the use does not expand to require additional spaces (see § 17.37.020(D) and the parking chapter). Before you propose changes, consult Portola Parking standards to confirm whether your change triggers new parking counts.
Nonconforming parcels (lots that are smaller than today’s minimums) may still be used as building sites if they were lawfully created (for example, part of an approved subdivision) or meet the proof criteria in § 17.37.030. Confirm ownership records and subdivision approvals; the applicant bears the burden of evidence.

Checklist — what an applicant must satisfy for a proposed action affecting a nonconforming use/structure

Identify the controlling nonconformity: use vs. structure vs. parcel and confirm pre‑existing lawful status per § 17.37.020(A).
Confirm whether your property lies inside an overlay (OT, DC, FP) — overlays may add or supersede requirements; consult Portola Overlay Districts and Portola Design Review.
If proposing expansion of a nonresidential nonconforming use in commercial or industrial zones, prepare a Conditional Use Permit (CUP) application and the findings required by § 17.88.060 and § 17.37.020(B)(3).
If substituting one nonconforming use for another, verify that the new use is equal or less intensive and prepare for a CUP per § 17.37.020(B)(4).
If the nonconforming issue is parking, check § 17.37.020(D) and Portola Parking to determine whether your proposal triggers additional parking requirements.
If the structure was damaged or destroyed, get an inspection/valuation from the building inspector and follow the procedures and timing in § 17.37.020(E) (≤50% vs >50%). Also verify FP restrictions if in floodplain.
If the use has been discontinued, verify the six‑month abandonment rule in § 17.37.020(F) — if >6 months, the nonconforming status is lost.
For undersized lots, collect subdivision records or other proof required by § 17.37.030 to demonstrate a nonconforming parcel may be used as a building site.

Risks & Ambiguities

Issue	Why it matters	What to verify
Exact numeric R‑1 development standards not located in retrieved snippets	The nonconforming residential-in‑nonresidential rule points to R‑1 standards; without the numeric R‑1 table you cannot confirm setbacks, lot size, height, etc.	Look up § 17.16.030.A and the R‑1 development standards on the official Portola zoning tables or confirm with the Planning Department. Not found in retrieved materials.
Floodplain interactions with reconstruction	Floodplain overlay can restrict reconstruction even where Chapter 17.37 would otherwise allow it; failure to apply FP requirements can block permits.	Confirm floodplain status and applicable FEMA FIRMs and follow § 17.28.020 for encroachment and elevation rules.
Which approvals are required (CUP vs. variance) after >50% damage	The code separates nonconforming use vs nonconforming building for >50% damage with different approval paths (CUP vs variance) and timeframes.	Check § 17.37.020(E) carefully and confirm with building inspector and planning staff before preparing reconstruction documents.
Nonconforming parking reconstruction vs parking table triggers	A building change that appears minor could still increase parking requirements under Chapter 17.40 and thereby invalidate the "no expansion" allowance.	Run a parking count analysis against § 17.40.030 and cite § 17.37.020(D) when submitting plans.
Adult‑oriented business amortization	Separate amortization rules exist for adult‑oriented businesses with stricter abandonment periods and a five‑year phase‑out possibility.	If the nonconforming use is an adult‑oriented business, consult § 17.49.040; special amortization rules may apply.

Plain-English Summary

Portola lets legally existing uses that no longer match current zoning continue, but generally not grow. Nonresidential nonconforming uses in commercial/industrial zones may expand only with a Conditional Use Permit; residences that are out of place must meet the city's R‑1 residential standards. If a nonconforming use stops for six months, it’s gone; if a building is badly damaged, there are strict reconstruct/replacement rules and floodplain checks. Key citations: § 17.37.020 and § 17.37.030.

Source References

§ 17.37.010 – 17.37.030 (Chapter: Nonconforming Uses, Structures and Parcels) — governing purpose, continuation, expansion limits, parking, damage/reconstruction, abandonment, and nonconforming parcels.
§ 17.16.010 (Residential zones purpose; reference to R‑1 standards) — identifies residential districts and points to R‑1 development standards.
§ 17.19.030 (Commercial zone general development standards — CC, CMU, SC) — tables for minimum lot size, setbacks, frontage.
§ 17.22.030 (Industrial zone general development standards — BP/LI) — minimum lot sizes, setbacks, site coverage, height.
§ 17.28.020 (Floodplain FP overlay: permitted uses, encroachment standards) — floodplain rules that can alter reconstruction options for nonconforming buildings.
§ 17.40.030 (Parking Space Requirements by Use Type) — referenced by nonconforming parking rules.
§ 17.70.040 (Accessory Dwelling Unit design & development standards) — includes ADU allowances when the primary structure is nonconforming (§ 17.70.040(I)). See Portola ADUs.
§ 17.49.040 (Amortization of nonconforming adult‑oriented business uses) — special amortization/abandonment rules for adult‑oriented businesses.

Sources

Retrieved passages

Portola Zoning Code (§ 1) High relevance
Portola Zoning Code (Section 17.40.030.) High relevance
Portola Zoning Code (Title 17) High relevance
Portola Zoning Code (Section 17.37.020.C.2) High relevance
Portola Zoning Code (§ 2) High relevance
Portola Zoning Code (Section 17.37.020) Medium relevance
CBC § 1974 Medium relevance
CBC § 66321 (§ 66321) Medium relevance
Portola Zoning Code (Chapter 17.52.) High relevance
Portola Zoning Code (section shall) Medium relevance
Portola Zoning Code (§ 66314) Medium relevance
Portola Zoning Code (§ 66333) Medium relevance
Portola Zoning Code (chapter which) Medium relevance
Portola Zoning Code (Chapter 17.28) Medium relevance
CBC § 66314 (§ 66314) Medium relevance
Portola Zoning Code (title to) Medium relevance
CBC § 1 (Title 24) Medium relevance
Portola Zoning Code (Article II) Medium relevance
Portola Zoning Code (chapter which) Medium relevance
CFC § 600 (Title 24) Medium relevance
Portola Zoning Code (Section 65852.2) Medium relevance

Cited sections

Official Portola code library

Frequently asked questions

What is a “nonconforming use” in Portola?

A nonconforming use is a use that was lawful when established but no longer complies with current zoning rules because the zoning changed. The rules governing continuation, limits on enlargement, substitution, and loss of nonconforming status are in § 17.37.020.

Can I expand a nonconforming business in a commercial zone?

You can only expand a nonconforming nonresidential use in a commercial or industrial zone if you obtain a Conditional Use Permit; the CUP must meet the findings in § 17.88.060 and the limits in § 17.37.020(B)(3).

If my nonconforming building is 60% damaged, can I rebuild?

Damage over fifty percent of the building’s value triggers stricter rules: reconstruction of a building with a nonconforming use may require a CUP or other approvals and is subject to time limits described in § 17.37.020(E); floodplain rules may apply if the parcel is in FP. Verify with the building inspector.

How long before a nonconforming use is considered abandoned?

If a nonconforming use is discontinued for six months, it is deemed abandoned and the property must be used in compliance with current zoning rules going forward, per § 17.37.020(F).

What happens if a residence exists in a commercial zone?

An existing residential building in a nonresidential district may continue as a residence but must meet the R‑1 residential development standards (see § 17.37.020(B)(1) and § 17.16.030.A). Numeric R‑1 standards should be confirmed in the full R‑1 development table.

Can I replace a nonconforming use with a different use?

You may substitute a different nonconforming use only if it is the same or a less intensive use classification and only upon approval of a CUP; the new use must occupy the same area as the existing nonconforming use (see § 17.37.020(B)(4)).

Are undersized (nonconforming) lots buildable?

Yes, an undersized parcel may be used as a building site if you can prove it was lawfully created (e.g., part of an approved subdivision) and meets the criteria in § 17.37.030; the applicant bears the burden of evidence.

Does nonconforming parking prevent reconstruction?

You can reconstruct or alter a building with nonconforming parking provided the project does not expand the use in a way that requires additional parking per § 17.40.030; otherwise you may have to correct parking deficiencies. See § 17.37.020(D).

Are there special rules for adult‑oriented businesses that are nonconforming?

Yes — adult‑oriented businesses have special proximity and amortization rules; nonconforming adult‑oriented uses may be terminated within five years of an ordinance effective date unless extended per § 17.49.040. Check that section if this applies.

If my primary structure is nonconforming, can I add an ADU?

Portola allows an ADU when the primary structure is nonconforming only if the ADU does not increase the degree of nonconformity (see § 17.70.040(I)). Also check state ADU law for additional protections. See Portola ADUs and California ADU law.

Ask about any Portola property

Get a cited, plain-English answer on Portola zoning, setbacks, FAR, ADUs and permits — for any address.

Start Free Trial