Local zoning · La Mesa

La Mesa — Historic Preservation

Historic Preservation under the La Mesa local zoning and planning code, with the controlling citations.

Last reviewed: July 2, 2026

Overview

La Mesa’s zoning code treats historic resources as a distinct planning consideration: locally designated historical landmarks and properties on state inventories receive special rules that affect density, accessory dwelling units (ADUs), and the eligibility for certain housing types. Consult the city's base zoning map and development standards before making changes; the code and map are part of the city's zoning program and overview for applicants. § 24.05.026, § 24.05.032, and § 24.05.020 provide the core local rules for historic sites.

(If you need the citywide context before reading this page, see the La Mesa zoning & planning overview.) /us/california/la-mesa

What the La Mesa code actually says (practical synthesis)

Density bonus for local landmarks: a property that contains a locally designated historical landmark may receive an increase of one dwelling unit above the zoning district’s otherwise permitted dwelling count; this bonus is specifically applicable in R zones with the exception noted for R1 lots that already contain an allowed ADU. § 24.05.026.
Two-unit development exclusions: the objective two-unit (ADU/duplex-style) standards explicitly prohibit a two-unit residential development on lots that (a) have a designated historic landmark, (b) are listed on the State Historic Resources Inventory, or (c) lie within a designated historic district. See § 24.05.032.E.1.
ADUs on historic sites: ADUs are allowed on properties that are designated historic or inside historic districts only when the ADU’s location and design meet the historic preservation requirements in place at the time of construction; detached ADUs must generally be located behind the primary/historic structure; ADUs may not remove or alter historically significant features; ADUs must be compatible in style/materials with the historic building; and a Mills Act contract must be amended as needed. These rules are in the ADU chapter. § 24.05.020 D8(c)(i–vi).
Non-residential uses in local landmarks: the residential development standards identify that, when located within a locally designated historical landmark, certain non-residential uses may be allowed (for example, professional offices, retail sales compatible with the building’s historic status, bed & breakfast inns, and restaurants), subject to the usual conditional-use or design-review procedures. § 24.05.030.
Design review and site development: historic-related changes that implicate design or site development review are processed under the city’s site development plan and urban design review rules. See § 24.02.035 (site development plan) and § 24.02.036 (urban design review). If a historic property triggers discretionary review, the planning commission/city council process and findings apply.
Parking and other objective standards: parking reductions or requirements for housing projects must consider historic resource impacts; ADUs and two-unit projects have specific parking rules (including limited or no additional parking required in many cases). See the parking rules tied into the two-unit and ADU sections; consult the city's parking requirements for full details. § 24.05.032.I and § 24.05.020.f. (Also see the city parking chapter for design standards). /us/california/la-mesa/parking
Overlays and historic sites: overlay zones (for example, Scenic Preservation, Urban Design, Hillside) still apply to historic properties where the overlay is mapped; ADU and two-unit rules explicitly cross-reference overlay chapters where relevant. Verify overlay application on the zoning map. (Zone map adoption rules appear in the code.) § 24.01.050 and overlay-related cross-references in the ADU/two-unit chapters. /us/california/la-mesa/overlay-districts
State building standards / historic code: historic structures may qualify for alternate treatment under the State Historical Building Code and related Title 24 provisions; verify building-code compliance with the Building Department and reference the California Building Standards Code. (See the California historical code excerpts incorporated by reference by practice.) Consult the statewide code for life-safety variances that explicitly address historic structures. Not a zoning rule, but relevant to feasibility. /us/california/building-codes
Practical constraint: two-unit development and some ADU paths are explicitly limited on historic lots; at the same time, a local landmark can qualify a site for a one-unit density bonus — those two rules can pull in opposite directions, so plan early and confirm designation status. § 24.05.032.E and § 24.05.026.

(For background on setbacks and dimensional rules referenced below, see the city's development standards.) /us/california/la-mesa/development-standards

District-by-district breakdown (how historic rules interact with La Mesa zones)

Notes: the code’s residential development standards are centralized in the residential chapter; the numeric examples below are taken from the La Mesa table of dimensions. See § 24.05.030 for the full table and explanatory notes.

R1 (single-family residential)

Purpose: typical single-family neighborhood preservation and low-density housing. § 24.05.030.
Typical permitted uses: single-family dwellings; when a building/site is a locally designated historical landmark, compatible non-residential uses (professional office, compatible retail, bed & breakfast, restaurant) may be allowed subject to review. § 24.05.030.
Key dimensional standards (from the residential dimensions table): Front setback: 15 ft (note exceptions), Side setback: 5 ft, Rear setback: 15 ft, Maximum height: 20 ft, Coverage: 40%. § 24.05.030.
Historic specifics: two-unit development is prohibited on R1 lots that are local landmarks or in state inventory; ADUs remain possible only if they comply with the historical-site ADU rules § 24.05.032.E and § 24.05.020 D8(c).

R2 (lower-multiplex/residential)

Purpose: medium-low density multiple dwelling. § 24.05.030.
Typical uses: duplexes, small multifamily; same historic allowances as noted—uses located within a designated historical landmark may be conditionally permitted following the code’s rules. § 24.05.030.
Key dimensional standards: Front setback: 15 ft, Side setback: (5 ft per applicable rules), Height: 20 ft, consult the table in § 24.05.030 for full values.
Historic specifics: two-unit development rules (and the exceptions) are in § 24.05.032; ADU rules still apply but must meet the historical-site ADU subsection.

R3 (higher-density residential)

Purpose: larger apartment scale where allowed. § 24.05.030.
Typical uses: multifamily dwellings, subject to density limits. Historic properties in R3 still carry the same local-landmark protections; ADUs and two-unit rules apply per the cited sections. § 24.05.020, § 24.05.032.

RB (Residential-business zone)

Purpose: mixed residential and neighborhood-serving commercial where compatible. § 24.05.030.
Typical permitted uses: the chapter lists permitted and conditionally permitted uses; specially, when a building/site is a locally designated historical landmark, uses such as professional office, retail, bed & breakfast, and restaurant are possible with appropriate approvals. § 24.05.030.
Dimensional standards: RB-specific values in the residential table (see § 24.05.030 table); height: 30 ft shown for RB in the table excerpt.

Overlay zones (Scenic Preservation / Urban Design / Hillside)

Purpose: overlays modify development rules or add review standards that may affect historic properties; ADU and two-unit provisions expressly reference overlay chapters when applicable (e.g., Scenic Preservation Chapter 24.09; Urban Design Chapter 24.11; Hillside Chapter 24.13). See the ADU subsection cross-references in § 24.05.020 and the zone-map adoption § 24.01.050 for mapping. /us/california/la-mesa/overlay-districts

Quick reference table — decision‑relevant standards & common code citations

Rule / permitted change	Simple rule	Code Reference
Density bonus for local landmark	+1 dwelling unit allowed (R zones; limitation for some R1 lots)	§ 24.05.026
Two‑unit (ministerial duplex/urban‑lot split) on historic lots	Prohibited on lots with a local landmark, on State Historic Resources Inventory, or in a designated historic district	§ 24.05.032.E.1
ADU on historic site	Allowed only if location/design meet historical preservation requirements; detached ADU behind primary/historic structure; no demolition/alteration of significant features	§ 24.05.020 D8(c)(i–vi)
Non‑residential uses in local landmarks	Professional office, compatible retail, bed & breakfast, restaurants may be allowed subject to review	§ 24.05.030
Site development & design review	Major changes may trigger site development plan or urban design review (public notice, findings)	§ 24.02.035 and § 24.02.036
Parking for ADUs / two‑unit projects	Specific exemptions and limited parking requirements; see ADU and two‑unit sections for when parking is not required	§ 24.05.020.f–g, § 24.05.032.I

Checklist (what an applicant must satisfy before proposing changes on a historic property)

Confirm whether the property is a locally designated historical landmark, on the State Historic Resources Inventory, or inside a designated historic district (Verify with the jurisdiction). § 24.05.032.E.1.
If claiming the density bonus for a local landmark, prepare the housing plan showing the +1 unit and follow the density-bonus procedures and any affordable-housing agreement requirements. § 24.05.026.
For ADUs: prepare drawings demonstrating the ADU’s location, materials, and how it preserves historic features (ADU must meet historical preservation requirements and ADU rules). § 24.05.020 D8(c). /us/california/la-mesa/adu
Check whether the project triggers site development plan or urban design review and be ready to submit for § 24.02.035 and/or § 24.02.036 review. /us/california/la-mesa/design-review
Show that the proposal will not demolish, alter, or move the historic building or features (ADUs cannot cause removal of historically significant accessory structures). § 24.05.020 D8(c)(iii–v).
If proposing two-unit/urban-lot-split development, confirm the lot is not excluded by the historic prohibition; if excluded, pursue alternative approaches (ADU where allowed, adaptive reuse, or conditional uses). § 24.05.032.E.
If the property is under a Mills Act contract, confirm/amend the contract as necessary before adding an ADU. § 24.05.020 D8(c)(vi).
Check parking implications early; consult the parking chapter and the ADU/two‑unit parking exemptions. § 24.05.020.f, § 24.05.032.I. /us/california/la-mesa/parking

Risks & Ambiguities

Issue	Why it matters	What to verify
Whether a parcel is “locally designated” vs. merely listed on a state inventory	Controls whether two‑unit development is allowed and whether density bonus applies	Confirm local designation status with Community Development / Planning (designation rolls). § 24.05.032.E.1 and § 24.05.026.
Exact preservation standards that “meet corresponding historical preservation requirements”	Code requires compliance but does not include full treatment standards in the ADU section	Request the city’s historic design guidelines or preservation standards (Not found in retrieved materials). Verify with the jurisdiction.
Whether a proposed ADU’s location is “behind the primary/historic structure”	The phrase is in the ADU rules but site-specific interpretation varies and may trigger discretionary review	Provide site plan, elevations, and photos; ask the planning director for an interpretation. § 24.05.020 D8(c)(ii–v).
Interaction with overlay requirements (Scenic/Urban Design/Hillside)	Overlays can add standards or trigger commission review even if ADU rules allow ministerial approval	Confirm mapped overlays on the property and which overlay chapters apply; see zone map § 24.01.050 and overlay cross-references in ADU chapter.
Whether a Mills Act contract will allow the change (ADU, density bonus)	Mills Act protections and tax implications may require an amended contract	If a property is under Mills Act, coordinate with the City and County, and obtain any required contract amendment. § 24.05.020 D8(c)(vi).

Plain-English summary

If your La Mesa property is a local historic landmark or is listed on the state historic inventory, you cannot use the ministerial two‑unit/urban‑lot‑split pathway there, but the city will allow a one‑unit density bonus for locally designated landmarks and will permit ADUs only if they are sited and designed to preserve the historic building and its character — expect site plans and design-review checks and verify designation and overlays with planning early. § 24.05.026, § 24.05.032, § 24.05.020.

Information Gaps (what the code excerpts did not show)

The local procedure, criteria, and decision body for designating a property as a La Mesa historical landmark (the code references designated landmarks but the designation procedure text was Not found in retrieved materials). Verify with the City’s historic preservation program.
Detailed historic‑preservation design guidelines or a preservation handbook that explain the phrase “meets corresponding historical preservation requirements” (Not found in retrieved materials). Request local design guidelines from the planning department.
A mapped list/online map of locally designated historic resources and historic districts in La Mesa (Not found in retrieved materials). Verify with the Planning Department.

Source References

§ 24.05.026 — Density bonus for historical landmarks.
§ 24.05.030 — Residential development standards and permitted/conditional uses (including uses allowed within locally designated historical landmarks).
§ 24.05.032 — Two‑unit residential development and urban lot split rules, including the prohibition for historic lots.
§ 24.05.020 D8(c) — Accessory dwelling unit rules for historical sites and districts (ADU location, design, and Mills Act cross-reference).
§ 24.02.035 — Site development plan review procedure.
§ 24.02.036 — Urban design review (design review board/urban design program).
§ 24.01.050 — Zoning map adoption and overlay mapping context.
California Historical Building Code excerpts and the CHBC approach to historic structures (for building-code treatment and life‑safety variances; referenced for context).

(If you want the local ordinance pages or the official online code links, request them and I’ll point to the exact La Mesa municipal code web pages or assist with a permit checklist tailored to a specific parcel. Verify all parcel-specific questions with the City of La Mesa Community Development Department.)

Sources

Retrieved passages

La Mesa Zoning Code (§ 5) Medium relevance
CBC § 24.05.032 (title shall) Medium relevance
CFC § 24.05.030 (Section 24.05.030G.) Medium relevance
La Mesa Zoning Code (chapter for) Medium relevance
La Mesa Zoning Code (§ 2) Medium relevance
La Mesa Zoning Code (Chapter 24.13) Medium relevance
La Mesa Zoning Code (chapter for) Medium relevance
La Mesa Zoning Code (Section 24.05.030G.) Medium relevance
La Mesa Zoning Code (§ 1) Medium relevance
La Mesa Zoning Code (Title 22) Medium relevance
La Mesa Zoning Code Medium relevance
La Mesa Zoning Code (§ 65915) Medium relevance
CBC § 66314 (§ 66314) Medium relevance
La Mesa Zoning Code (Chapter 24.09) Medium relevance
CBC § 66321 (§ 66321) Medium relevance
California Fire Code Medium relevance

Cited sections

Official La Mesa code library

Frequently asked questions

What counts as a “designated historical landmark” in La Mesa?

A “designated historical landmark” is a property the city recognizes as historic and that triggers the local protections described in the zoning code; the zoning rules assume the existence of such designations but the code excerpts supplied do not include the local landmark designation procedure itself — verify designation status with La Mesa planning. § 24.05.032.E.1.

Can I build an ADU on a La Mesa house that’s a local historic landmark?

Yes — but only if the ADU’s siting and design comply with the historical-preservation requirements in effect at the time of construction, the detached ADU is located behind the primary historic structure, and the ADU does not remove/alter on-site features that convey historic significance. See § 24.05.020 D8(c)(i–v).

Does a local landmark get any zoning benefit in La Mesa?

Yes — a property containing a locally designated historical landmark may receive a one-unit density bonus above the parcel’s permitted dwelling count in R zones (with R1 exceptions). § 24.05.026.

Am I allowed to do a ministerial two‑unit conversion on a historic lot?

No — the two‑unit residential development pathway is explicitly prohibited on lots that are local landmarks, on the State Historic Resources Inventory, or within a designated historic district. § 24.05.032.E.1.

Do historic properties have to follow overlay (Scenic/Urban Design/Hillside) rules?

Yes — overlay zone rules still apply where mapped; the ADU and two‑unit provisions explicitly cross‑reference overlay chapters, and overlay standards may add requirements or review steps. Verify overlay mapping on the zoning map. § 24.05.020 cross‑references overlays and § 24.01.050 covers the zone map. /us/california/la-mesa/overlay-districts

Will adding an ADU to a historic site trigger a design review?

Possibly — ADU rules allow ministerial approval in many cases but require that ADUs on historic sites meet preservation requirements; the ADU chapter also references overlay chapters and the city’s design-review/site‑development review processes (§ 24.02.035 / § 24.02.036) for projects requiring discretionary review. § 24.05.020 D8(c) and § 24.02.036. /us/california/la-mesa/design-review

If my property is under a Mills Act contract, can I still add an ADU?

Possibly, but the ADU chapter requires that the Mills Act contract be amended as needed to authorize the ADU on the site. Confirm with the City and county tax authority before proceeding. § 24.05.020 D8(c)(vi).

Where are the setback and height numbers I must meet for an ADU on a historic lot?

ADUs must comply with the underlying zone’s development standards unless the ADU provisions provide a specific exception (example: minimum 4‑ft side/rear setbacks for many ADUs). See the residential dimensions table in § 24.05.030 and the ADU setback rules in § 24.05.020. § 24.05.030 and § 24.05.020 D8.b–c. /us/california/la-mesa/development-standards

Are there parking exemptions for ADUs on historic properties?

The ADU chapter states that new or additional parking is generally not required for ADUs in many circumstances, and the two‑unit chapter contains specific parking rules; however, verify any site-specific overlay or design conditions. See § 24.05.020.f and § 24.05.032.I. /us/california/la-mesa/parking

If I want to change the use of a local landmark to a small shop or office, how is that handled?

The residential chapter lists certain non‑residential uses that may be allowed when located within a locally designated historical landmark (e.g., professional offices, compatible retail, bed & breakfast, restaurants), but each use will be subject to the conditional‑use or design review and required findings in § 24.05.030.

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