ADUs on Historic Properties

Article IVH categorically exempts ADUs from the Certificate of Appropriateness requirement. SPMC 2.65(d)(6) reads: “all alterations affecting an existing or proposed accessory dwelling unit” are exempt. There is no qualifier and no carve-out within Article IVH itself.

An owner adding an ADU on a property in the South Pasadena Inventory of Cultural Resources does not need a Certificate of Appropriateness from the Cultural Heritage Commission for the ADU itself.

The zoning code runs a parallel review framework. SPMC 36.350.200(J) — the historic-property provision within the ADU ordinance — establishes objective design standards that ADUs on Inventory properties must meet to qualify for ministerial (staff-level) approval under California’s by-right ADU framework.

The standards address visibility from the public right-of-way; location on the lot; size and height relative to the primary dwelling; setbacks; orientation; materials; roof types and pitches; wall cladding; doors; and windows. The City’s published ADU Design Guidelines for Historic Properties (Architectural Resources Group, November 2021) explains these standards across approximately 90 pages with diagrams and examples.

If the ADU project meets all the objective design standards, it proceeds through ministerial approval. There is no discretionary Cultural Heritage Commission hearing, and no Certificate of Appropriateness is required.

If the project does not meet one or more standards, it requires Cultural Heritage Commission review under the zoning code provision — not under the Article IVH Certificate framework. The Commission then reviews the project against the design guidelines and the Secretary of the Interior’s Standards through the zoning-code track.

The standards consider an ADU “visible from the public right-of-way” if it is visible from the street immediately in front of and within 10 feet on either side of any street-adjacent property line. For corner properties, both adjacent streets are considered. Alleys do not count as public right-of-way for this purpose.

Vegetation, gates, fencing, and other landscaping are not factored into the visibility test — they cannot be relied on to bring an otherwise visible structure under the threshold. ADUs that are not visible by this test are exempt from the design standards entirely.

The ADU paths most commonly available on South Pasadena historic properties are detached new construction, conversion of an existing accessory structure, addition to an existing accessory structure, and a Junior ADU within the existing primary dwelling. The City’s published ADU permit application reflects this set of options for historic-resource projects, and the ARG Design Guidelines develop the design-standards framework for them. The attached-ADU path on historic residences is materially constrained by the design standards at SPMC 36.350.200(J) and the City’s interpretation, consistent with CEQA Guidelines § 15331, that attaching an ADU to a historic dwelling carries review implications beyond what the State’s by-right framework readily accommodates. Before treating an attached ADU on a historic property as a workable path, an owner should confirm the current zoning-code text at SPMC 36.350.200(J) and the City’s most recent application materials with Community Development.

Source: South Pasadena Municipal Code Chapter 2, Article IVH (Cultural Heritage Ordinance, Ord. No. 2315 § 2, 2017), § 2.65(d)(6). SPMC Chapter 36, § 36.350.200(J) (ADU ordinance — historic property provisions). City of South Pasadena, Design Guidelines for ADU Development on Historic Properties, prepared by Architectural Resources Group, November 2, 2021. CEQA Guidelines § 15331. California Government Code § 65852.2.