Local zoning · San Carlos

San Carlos — Historic Preservation

Q: Are landscaping rules different for registered historic sites?

Yes — Chapter 18.18 exempts “landscaping that is part of a registered historic site” from some of the landscape standards; you must document registered historic status to claim the exemption ( § 18.18.020(B) ).

Q: Can the City impose conditions that reduce my allowed FAR or density to protect historic character?

Under § 18.29.080 , the City may impose conditions related to design review, but the review authority may not impose conditions that reduce residential density or floor area ratio below the standards in Title 18 if that would conflict with a valid use permit or variance. Read § 18.29.080 closely and be prepared to appeal.

Historic Preservation under the San Carlos local zoning and planning code, with the controlling citations.

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Last reviewed: July 2, 2026

Overview

San Carlos does not have a standalone "historic preservation" chapter in the uploaded Title 18 materials, but the Zoning Ordinance embeds historic-resource controls and special rules in several places: sign rules for historic sites, eligibility limits for SB 9 subdivisions, exemptions for landscape rules on registered historic sites, and multiple points where design review must consider compatibility with historic or unified visual character. Key controlling provisions include § 18.22.120, § 18.23.310, § 18.18.020, and the design review chapters § 18.29.060–§ 18.29.080.

NOTE: Where the ordinance refers to a City “Historical Resources Survey,” landmark designation, or the State Historic Resources Inventory, the implementing details (how the City adopts a historic district or landmark) are not shown in the retrieved materials. Verify with the jurisdiction for parcel-specific historic designations. Not found in retrieved materials.

How San Carlos’ Title 18 treats historic resources — district-by-district and topic breakdown

Below are the specific places in the Zoning Ordinance where historic-preservation-related rules appear, organized by the district or topic the code actually references.

Parcels designated as a historic district / City or County landmark (designation and status)

Purpose / effect: parcels that are identified as part of a recognized historic district, listed on the State Historic Resources Inventory, or designated as a City/County landmark receive special treatment in other chapters (limitations, exemptions, or eligibility rules). The code treats such parcels as not eligible for certain by-right subdivision/development paths. See § 18.23.310(c).
Typical implications: ineligibility for the Senate Bill 9 (urban infill) subdivision path; eligibility for special historical sign permits (see signs section); landscape exemptions for registered historic sites (see § 18.18.020).
Where it applies: any parcel "located within an historic district or included on the State Historic Resources Inventory, as defined in Section 5020.1 of the Public Resources Code, or a parcel within a site that is designated or listed as a City of San Carlos or San Mateo County landmark or historic property or district" per § 18.23.310(c).

RS-3 and RS-6 (single‑family residential districts) — SB 9 / Urban Infill references

Purpose: the SB 9 / urban infill rules in Chapter 18.23.310 set objective standards for lot splits and small-lot development in single‑family zones (RS-3, RS-6 are the base districts named in that chapter). The code explicitly excludes parcels in historic districts or designated landmarks from eligibility. See § 18.23.310.
Typical permitted uses: standard single‑family uses per the RS district (see base district tables elsewhere in Title 18); SB 9 two‑lot subdivisions are allowed only where the parcel is not within a historic district or listed resource.
Key dimensional standards (as applied to SB 9/urban infill): limits on parcel creation, minimum parcel sizes, and objective setback/coverage standards in Chapter 18.23.310; but if the parcel is in a historic district, SB 9 is disallowed per § 18.23.310(c).

Downtown / Downtown Specific Plan area

Purpose: the Downtown Specific Plan area has its own applicability rules and design expectations; the code calls out the historic train depot and Drake building in gateway design guidance. See § 18.14.1.020 and gateway criteria § 18.11.030.
Typical effect for historic resources: projects in downtown are subject to the general design review chapter and must show compatibility with historic/visual character where applicable (see Design Review below).

G Overlay (Gateway) and other Overlay Districts (e.g., Hillside H, Northeast Area Overlay)

Purpose: overlay districts add design and development standards; the Gateway (G) Overlay mentions proximity to the historic train depot and includes design criteria that emphasize compatibility with local landmarks. See § 18.11.010–§ 18.11.040.
Effect on historic preservation: overlay design criteria are enforced via the design review process; where historic character is a recognized attribute, the design-review criteria require compatibility with it (see § 18.29.060).
The Northeast Area Overlay District requires conditional use permits and design review for many projects while the Specific Plan is pending; historic-property status in overlays may further affect discretionary review. See § 18.14A.020–.040.

Design review (citywide procedural control that protects historic character)

Where it appears: design review is a citywide mechanism in Chapter 18.29. The code requires the design-review authority to determine whether a proposal is compatible with surrounding character; one explicit criterion is that the "proposed design is compatible with the historical or visual character of any area recognized by the City as having such unified character." That language is in § 18.29.060(G) (design criteria) and the required findings for approval are in § 18.29.070; conditions and limits on conditions are in § 18.29.080. See Chapter 18.29.
Practical effect: exterior alterations to buildings that affect historic appearance will typically trigger design review and may be conditioned to preserve character. Design review decisions can be appealed under the general appeals chapter.

Signs on historic properties

Historical signs: the code authorizes an historical sign permit (Planning & Transportation Commission) to allow nonconforming signs with historic value to remain, subject to findings including that the sign is at least 30 years old and structurally sound. See § 18.22.120.

Landscaping rules and registered historic sites

Exemption: Chapter 18.18 (trees/landscaping) expressly exempts “landscaping that is part of a registered historic site” from some of that chapter’s standards. See § 18.18.020(B).

Quick reference table — decision‑relevant standards / uses

Decision‑relevant topic	What the code says (plain)	Code reference
Historical signs — permit to retain historic signs	Historic signs may be permitted if ≥ 30 years old, structurally sound, and visually appropriate; process is a Planning & Transportation Commission use permit	§ 18.22.120
SB 9 / Urban infill exclusions	Parcels in an historic district, on the State Historic Resources Inventory, or designated City/County landmark are ineligible for the SB 9 urban‑infill subdivision path	§ 18.23.310(c)
Design review — historic character criterion	Design review must find the project is compatible with the historical or visual character where the City recognizes such character	§ 18.29.060(G); findings § 18.29.070; conditions § 18.29.080
Landscape exemptions for historic sites	Landscaping that is part of a registered historic site is exempt from certain Chapter 18.18 standards	§ 18.18.020(B)
Downtown gateway / landmarks referenced in design	Gateway criteria call out the historic train depot and Drake building as context for design	§ 18.11.030; Downtown Specific Plan applicability § 18.14.1.020

Checklist — what an applicant must satisfy (historic/resource‑sensitive work)

Confirm whether the parcel is listed on the San Carlos Historical Resources Survey or the State Historic Resources Inventory (verify with City). Not found in retrieved materials for the City's survey list.
If the work involves signs that predate modern rules, prepare an historical sign permit application addressing § 18.22.120 findings (age, structural report, design appropriateness).
If the project is in RS‑3 or RS‑6 and you are pursuing an SB 9 subdivision, confirm the parcel is not in a historic district or a designated landmark per § 18.23.310(c).
Prepare design materials showing compatibility with historic character to satisfy the design‑review criteria in § 18.29.060 and findings in § 18.29.070; be ready for conditions under § 18.29.080. Link your drawings to the design review criteria.
If claiming a landscaping exemption for a registered historic site, reference § 18.18.020(B) and supply documentation of registered historic status.
Confirm whether other overlays (e.g., G Overlay, Northeast Area Overlay) apply to the parcel and their design requirements; see overlay districts and § 18.11 / § 18.14A.
Expect appeals, conditions, and possible requirements for a use permit; see § 18.30.070 for use‑permit conditions where applicable.
Verify whether any proposed physical work triggers the California Building Standards Code (Title 24) or the California Historical Building Code; if so, coordinate with Building Official. (California Historical Building Code reference is in uploaded CHBC extract.)

Risks & Ambiguities

Issue	Why it matters	What to verify
Is my property officially on the City Historical Resources Survey?	Controls such as SB 9 exclusion and sign treatment hinge on formal designation.	Ask Planning/City Clerk for the San Carlos Historical Resources Survey or landmark inventory; verify parcel status. Not found in retrieved materials.
Is a proposed exterior alteration subject to design review or just ministerial review?	Design review is discretionary and allows conditions to preserve historic character; ministerial approvals are faster.	Confirm applicability of design review per Chapter 18.29 and whether the project triggers discretionary permits (see § 18.29.010–.050).
Are historical signs automatically allowed because a sign is old?	No — an historical sign permit requires findings (age, structural soundness, typical design, maintenance).	If the sign is ≥ 30 years, prepare structural documentation and an application per § 18.22.120.
Does SB 9 apply if only part of the parcel is historic?	Chapter 18.23.310 treats parcels located within an historic district or listed resource as ineligible; boundary/parcel specifics matter.	Verify the exact historic‑district boundaries and mapping with Planning.
Which standard controls when site development and building codes conflict?	Title 18 defers to more restrictive provisions; building‑code compliance is still required.	Confirm with Building Official whether California Building Codes or the California Historical Building Code apply. See California Building Standards Code and CHBC extract.
How are “registered historic sites” documented for landscaping exemptions?	The code exempts "landscaping that is part of a registered historic site" but does not show the registration procedure in the retrieved files.	Request documentation from the City on what qualifies as a “registered historic site.” Not found in retrieved materials.

Plain‑English summary

San Carlos spreads historic‑resource rules through its Zoning Ordinance rather than in a single historic‑preservation chapter: old signs can be kept under an historical sign permit (if they meet the 30‑year and safety findings, § 18.22.120), parcels in an official historic district or landmark are excluded from SB 9 urban‑infill parcel splits (§ 18.23.310), and any exterior work that affects visual character will be evaluated through the city’s design review criteria which explicitly require compatibility with recognized historic character (§ 18.29.060–.070). Always verify whether your parcel is on the City’s historic inventory — that status changes what rules apply.

Source References

§ 18.22.120 (Historical signs) — San Carlos Municipal Code excerpt (historical sign permit criteria).
§ 18.23.310 (Urban infill / SB 9 — parcel ineligibility for historic districts and listed resources) — San Carlos Municipal Code excerpt.
§ 18.18.020(B) (Landscape exemptions for registered historic sites) — San Carlos Municipal Code excerpt.
§ 18.29.060, § 18.29.070, § 18.29.080 (Design review criteria, findings, conditions) — San Carlos Municipal Code Chapter 18.29 excerpts.
§ 18.14.1.020 (Downtown Specific Plan applicability) and § 18.11.030 (Gateway design referencing the depot and Drake building) — San Carlos Municipal Code excerpts.
California Historical Building Code (uploaded CHBC excerpt) — for cases where historical-code provisions may apply to qualified historic buildings.
San Carlos Zoning & Planning overview: San Carlos zoning & planning overview
Title‑specific internal resources noted in text: San Carlos Zoning, San Carlos Development Standards, San Carlos Parking, San Carlos Overlay Districts, San Carlos Nonconforming Uses, San Carlos Variances and Exceptions, San Carlos ADUs, California Building Standards Code

Sources

Retrieved passages

San Carlos Zoning Code (title shall) Medium relevance
San Carlos Zoning Code (title or) Medium relevance
CBC § 1 (section states) Medium relevance
San Carlos Zoning Code (§ 3) Medium relevance
San Carlos Zoning Code (§ 1) Medium relevance
CFC § 5020.1 (Section 5020.1) Medium relevance
San Carlos Zoning Code (§ 3) Medium relevance
San Carlos Zoning Code (chapter and) Medium relevance
San Carlos Zoning Code (§ 4) Medium relevance
San Carlos Zoning Code (Chapter 12.28.) Medium relevance
CFC § 5020.1 (section is) Medium relevance
San Carlos Zoning Code (§ 1) Medium relevance

Cited sections

Official San Carlos code library

Frequently asked questions

Do I need design review for work on a house in San Carlos that’s historically significant?

If the work affects exterior appearance or is in an area where the City recognizes a unified historic or visual character, design review is likely required — Chapter 18.29 requires the reviewing body to find compatibility with historical or visual character (§ 18.29.060) and to make the required findings in § 18.29.070. Prepare to submit design drawings and to respond to conditions under § 18.29.080.

Can I use SB 9 (two‑lot split / duplex) on my San Carlos lot if it’s in a historic district?

No — parcels “located within an historic district or included on the State Historic Resources Inventory, or designated as a City/County landmark” are specifically listed as ineligible for the SB 9 urban‑infill subdivision path in § 18.23.310(c). Verify designation status with the City.

I have an old commercial sign from the 1950s — can it stay?

Possibly. The City authorizes an historical sign permit (Planning & Transportation Commission) for nonconforming historic signs if they meet findings such as being at least 30 years old, structurally sound, and visually appropriate (§ 18.22.120). You should expect to submit evidence of age and possibly a structural report.

Does Title 18 tell me how the City designates a "historic district" or a "landmark"?

Not in the retrieved Title 18 excerpts. The code references parcels “located within an historic district” and “listed as a City of San Carlos or San Mateo County landmark,” but the specific designation procedures or the City's formal inventory listing are not included in the materials provided. Verify with the City for the official survey/list and designation procedures. Not found in retrieved materials.

Are landscaping rules different for registered historic sites?

Yes — Chapter 18.18 exempts “landscaping that is part of a registered historic site” from some of the landscape standards; you must document registered historic status to claim the exemption (§ 18.18.020(B)).

If design review approves my alteration with conditions, can I appeal?

Yes — design review approvals and conditions are subject to the ordinance’s appeal provisions; design-review appeals follow the general appeals procedure noted in Title 18 (see § 18.29.090 and the appeal provisions referenced there).

If my historic building needs structural or life‑safety upgrades, do I follow the regular Building Code?

You must comply with applicable building codes; for qualified historic buildings the California Historical Building Code can provide alternate compliance paths. The San Carlos zoning materials acknowledge the need for building‑code compliance and the uploaded CHBC excerpt shows how historical code provisions can apply in those cases. Verify with the Building Official.

If a sign on my property was previously identified on the City historical survey, do I still need a historical sign permit?

If the sign has already been officially identified as an historic resource by inclusion on the San Carlos Historical Resources Survey or by another formal designation, the historical sign permit route in § 18.22.120 does not apply because such signs are considered authorized by their alternate designation. Confirm the sign’s status with Planning.

Can the City impose conditions that reduce my allowed FAR or density to protect historic character?

Under § 18.29.080, the City may impose conditions related to design review, but the review authority may not impose conditions that reduce residential density or floor area ratio below the standards in Title 18 if that would conflict with a valid use permit or variance. Read § 18.29.080 closely and be prepared to appeal.

What if my property’s historic status is ambiguous — who decides?

The City is the decisional body for permits; for discretionary actions the decision‑maker (Director, Planning & Transportation Commission, or City Council) will interpret whether the property qualifies as an historic resource in considering applications and required findings (design review, use permits, etc.). Where the ordinance relies on a formal survey or inventory, ask Planning for the official list. Not found in retrieved materials for the survey itself.

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