San Dimas — Historic Preservation

Last reviewed: July 2, 2026

Overview

San Dimas embeds historic-preservation controls inside its development-review, specific-plan, overlay, and sign chapters rather than in a standalone “historic preservation” chapter. The code recognizes a City historic inventory list and designated historic structures, routes changes through the city’s development plan / design-review process, protects “landmark features” in hillside and open-space areas, and provides narrow exemptions for historic signs. See the development-review rules in § 18.12.020 and the review-authority table in § 18.12.050 for the operative framework.

Note: wherever this page mentions processes such as design review, parking, overlay districts, signage, development standards, ADUs, or the California Building Standards Code, those words are linked to the City menu pages for quick navigation: design review, parking, overlay districts, signage, development standards, ADUs, California Building Standards Code. (Each link is used once at its first natural mention.)

How San Dimas treats historic resources (short list)

• Property on the City historic inventory list or a designated historic structure is subject to heightened review authority for additions, exterior changes and demolition (Planning Director or Planning Commission depending on the action). § 18.12.050.
• Demolition of inventory items or designated historic structures requires a historical significance evaluation and escalated review. § 18.12.050.
• “Historic signs” are explicitly recognized and may receive exceptions to normal sign standards with Planning/Director approval. § 18.152.250.
• The Planning Commission’s scope when reviewing development emphasizes conservation of natural and cultural landmarks (trees, rock outcroppings, skylines) in hillside areas and open space. § 18.164.060, § 18.510.190.

District-by-district breakdown

Note: the ordinance distributes preservation responsibilities across base zones, overlays, and specific plans. The subsections below summarize the parts of the code that directly affect historic-preservation outcomes; they cite the controlling sections. Verify parcel-specific application with the Community Development Department.

Creative Growth Zone — Area 3 (Downtown / historic-adjacent)

• Purpose: provide mixed-use downtown development while encouraging traditional architectural design to ensure compatibility with nearby historic neighborhoods. § 18.140.090.
• Typical permitted uses: retail, office, service, eating places (no drive-through), live/work units, multifamily consistent with traditional architectural styles. § 18.140.090.
• Key dimensional / design emphasis: buildings meant to “blend with traditional design standards” and storefronts encouraged; design review required under Chapter 18.12 for projects in this area. § 18.140.090; § 18.12.020.
• Where it applies: downtown San Dimas per the Specific Plan map (see § 18.140.090 exhibit on file). § 18.140.090.

Practical guidance: a property in Area 3 that is on the City’s historic inventory will face design-review expectations aimed at preserving traditional massing and storefront treatments; expect Planning Commission involvement for exterior changes that materially affect appearance. § 18.12.050.

Scenic Highway Overlay — (SHO)

• Purpose: protect visual character and historic/scenic vistas along designated corridors. § 18.108.030.
• Typical permitted uses: uses allowed by the underlying base zone remain permitted; overlay adds development standards. § 18.108.020 / § 18.108.030.
• Key standards: large required landscaped yards adjacent to designated streets (example: 25 ft along Foothill Boulevard; 50 ft along Via Verde in many locations), building siting to protect views/vistas, underground utilities, and street improvements. § 18.108.040.
• Where it applies: properties abutting designated scenic highways (map on the zoning map; SHO appended to base zone on official map). § 18.108.030.

Why it matters for preservation: if a historic building sits within an SHO the overlay’s setback, landscape and visual-protection rules will shape acceptable alterations and site changes. § 18.108.040.

Open Space Zone — OS

• Purpose: preserve open space and areas with outstanding scenic, historic and cultural values. § 18.124.010–§ 18.124.020.
• Typical permitted uses: preservation, recreation, natural-resource conservation; uses compatible with protecting scenic/historic character. § 18.124.020.
• Key standards: development subordinated to open-space purposes; special restrictions on grading and construction where scenic and historic values exist. § 18.124.010–§ 18.124.020.

Practical guidance: projects in OS that might impact historic/cultural landscapes will be assessed against open-space preservation findings and are subject to design/review protocols in Chapter 18.12. § 18.124.020; § 18.12.020.

Specific Plans that emphasize landmark preservation (examples)

• Specific Plan No. 7 (Via Verde area): contains grading and design rules that require preservation of “significant landmark features” (ridges, prominent trees, canyon areas) and restricts grading to blend with natural slopes. § 18.510.190; § 18.510.200.
• Other specific plans (e.g., No. 12, No. 17, No. 26) include tailored architectural guidelines and review procedures that may require Planning Commission or Director review and CEQA analysis for changes affecting historic or scenic resources. § 18.526.130, § 18.520.020, § 18.544.040.

Practical guidance: when a property lies inside a specific plan area, that specific plan’s preservation and architectural guidance govern — these may be stricter than base-zone rules and will control the review route (often Chapter 18.12). § 18.526.130; § 18.12.020.

Most decision-relevant items (quick table)

Checklist

• Confirm whether the property is on the City historic inventory list or is a designated historic structure (verify with Community Development). § 18.12.050.
• If demolition is proposed, prepare a historical significance evaluation per code triggers and expect escalated review. § 18.12.050.
• Prepare and file a complete Development Plan package per § 18.12.030 (site plans, elevations, materials, landscape, grading as required). § 18.12.030.
• If property lies within a Scenic Highway Overlay (SHO), show required landscape yards and siting measures (setbacks such as 25 ft on Foothill Blvd, 50 ft on Via Verde where applicable). § 18.108.040.
• If within a hillside specific plan, include tree plans and preserve identified landmark features; submit tree removal plan when grading is proposed. § 18.510.190, § 18.164.060.
• If proposing sign changes, document whether an existing sign is an identified historic sign and request Director/Planning exemptions if needed. § 18.152.250.
• Expect notice and the ability to appeal Director or Commission decisions under the development-plan chapter; appeals follow Chapter 18.212 timelines. § 18.12.060; § 18.12.050.

Risks & Ambiguities

Plain-English Summary

San Dimas does historic preservation through its development-review rules: if your building is on the City’s historic inventory or is officially designated, exterior changes and demolition trigger higher review (Director or Planning Commission) and a required historical-significance evaluation; hillside, scenic-highway and specific-plan areas add additional protections for visible landmarks and landscapes. Check with Community Development early to confirm inventory status and the exact review path. § 18.12.050, § 18.12.020, § 18.152.250, § 18.108.040.

Source References

• Development plan review / review triggers: § 18.12.020, § 18.12.030, Table § 18.12.050 (Development Plan Review Authority).
• Development-plan findings, notice, appeals, and decision rules: § 18.12.060, § 18.12.090.
• Historic signs and sign exceptions: § 18.152.250.
• Preservation of landmark features and scope of Planning Commission review (hillside/open space): § 18.164.060, § 18.510.190, § 18.510.200.
• Scenic Highway Overlay standards (setbacks, view protection): § 18.108.030, § 18.108.040.
• Open Space zone purpose and uses (including “areas of outstanding scenic historic and cultural values”): § 18.124.010, § 18.124.020.
• Specific Plan architectural guidelines and plan review references (various specific plans cited): § 18.526.130, § 18.520.020, § 18.544.040.

(If you need the exact text or full exhibits/maps for a parcel, request the specific plan exhibit or the City’s historic inventory from Community Development — the ordinance references these exhibits but the exhibits themselves were not included in the retrieved excerpts.) Not found in retrieved materials: explicit local historic-designation procedures, the full content/format required for a “historical significance evaluation,” and a public copy of the City’s historic inventory.

Retrieved passages

• CBC § 223.64 (§ 223.64) Medium relevance show source text
• San Dimas Zoning Code (section shall) Medium relevance show source text
• CBC § 18.510.180 (§ 18.510.180.) Medium relevance show source text
• San Dimas Zoning Code (§ 280.05) Medium relevance show source text
• San Dimas Zoning Code (§ 1) Medium relevance show source text
• San Dimas Zoning Code (chapter provides) Medium relevance show source text
• San Dimas Zoning Code (§ 1) Medium relevance show source text
• San Dimas Zoning Code (§ 18.164.040.) Medium relevance show source text
• San Dimas Zoning Code (§ 2) Medium relevance show source text
• CPC § 1A (§ 1A) Medium relevance show source text
• CBC § 1 (§ 1) Medium relevance show source text

Cited sections

• Development plan review / review triggers: **§ 18.12.020**, **§ 18.12.030**, Table **§ 18.12.050** (Development Plan Review Authority). (§ 18.12.020)
• Development-plan findings, notice, appeals, and decision rules: **§ 18.12.060**, **§ 18.12.090**. (§ 18.12.060)
• Historic signs and sign exceptions: **§ 18.152.250**. (§ 18.152.250)
• Preservation of landmark features and scope of Planning Commission review (hillside/open space): **§ 18.164.060**, **§ 18.510.190**, **§ 18.510.200**. (§ 18.164.060)
• Scenic Highway Overlay standards (setbacks, view protection): **§ 18.108.030**, **§ 18.108.040**. (§ 18.108.030)
• Open Space zone purpose and uses (including “areas of outstanding scenic historic and cultural values”): **§ 18.124.010**, **§ 18.124.020**. (§ 18.124.010)
• Specific Plan architectural guidelines and plan review references (various specific plans cited): **§ 18.526.130**, **§ 18.520.020**, **§ 18.544.040**. (§ 18.526.130)
• SanDimas_ZoningCode.md

• Official San Dimas code library