Secretary of the Interior’s Standards

The Secretary of the Interior’s Standards are the federal preservation framework that establishes how historic properties should be treated. They are promulgated by the National Park Service under authority of the National Historic Preservation Act of 1966 (16 U.S.C. §470 et seq.) and codified in two related parts of the Code of Federal Regulations:

• 36 CFR Part 68 — the Standards for the Treatment of Historic Properties (1995), covering all four treatment approaches.
• 36 CFR Part 67 — the Standards for Rehabilitation (1990), the most commonly applied subset, regulatory for the Federal Historic Preservation Tax Incentives program.

The Standards are not, by themselves, an LA-specific document. They are federal. Their relevance to HPOZ work in Los Angeles comes from the explicit reference adopted Preservation Plans make to them and from the way the design guidelines in those Plans are constructed on top of them.

The Standards for the Treatment of Historic Properties define four distinct approaches. One set applies to a property at a time, depending on the property’s significance, physical condition, and the project’s interpretive goals.

• Preservation. Sustaining the existing form, integrity, and materials of a historic property, with limited and sensitive upgrading where required for continued use.
• Rehabilitation. Repair, alteration, and additions necessary for an efficient contemporary use, while preserving those portions and features of the property significant to its historic, architectural, and cultural values. The treatment most commonly applied to HPOZ work, because most HPOZ projects involve continued residential or commercial use rather than museum-grade restoration.
• Restoration. Depicting a property at a particular period of time in its history, while removing evidence of other periods. Less common in HPOZ work; more typical of museum properties or landmark interiors.
• Reconstruction. Re-creating vanished or non-surviving portions of a property for interpretive purposes. Rare in HPOZ work, which typically deals with extant structures.

Per the National Park Service, the Standards are “common sense historic preservation principles in non-technical language” intended as general guidance applicable to all historic property types — buildings, structures, sites, objects, districts, and landscapes.

Adopted Preservation Plans across the LA HPOZ system reference the Standards explicitly. The relationship is foundation-with-override. Per language drawn from adopted Preservation Plans:

“All projects should comply with the Secretary of the Interior’s Standards, and where more specific guidelines have been set forth by this Preservation Plan, the guidelines herein should prevail.”

Two consequences follow.

The Standards are the default framework. Where the local Preservation Plan does not address a specific question, the Standards’ guidance applies. A project navigating an unusual condition — a mass-produced architectural element no one anticipated, a sustainability retrofit, a code-compliance alteration — is generally evaluated against the Standards even when the Plan is silent.

The Plan prevails where more specific. Where the Plan supplies a specific guideline — for example, a particular fenestration pattern, a specific roofing material, an explicit setback — that guideline controls over the more general Standards language. The Standards do not override district-specific guidance.

The hierarchy matches the broader pattern in the system: the citywide HPOZ Ordinance and Chapter 1A procedural framework set the procedural baseline, the Plan supplies district-specific design guidelines that prevail where more specific, and the Survey records the underlying classification each parcel carries. The Standards sit at the foundation of the design-guideline layer.

Adopted Preservation Plans typically restate the Standards as six derived principles applicable to HPOZ review. The six are paraphrased from the federal Standards, scoped to district-level work, and provided as the “basic principles on which these guidelines are based.” Per language drawn from adopted Preservation Plans:

• Principle 1. The historic appearance of the HPOZ should be preserved. This appearance includes both the structures and their setting.
• Principle 2. The historic appearance of contributing structures within the HPOZ should be preserved.
• Principle 3. The historic fabric of contributing structures should be preserved. Repair should be attempted before replacement.
• Principle 4. Replacement elements should match the original in materials, design, and finish as closely as possible.
• Principle 5. If historic design elements have been lost, conjectural elements should not be used. Every effort should be made to ascertain the original appearance of the structure, and to replicate that appearance.
• Principle 6. New additions should be designed to be compatible with the massing, size, scale, and architectural features of a historic structure or site, while clearly reflecting the modern origin of the addition. Additions should be designed to preserve the significant historic fabric of contributing structures or sites.

The six principles are not a substitute for the federal Standards; they are the local distillation. Where a project requires deeper analysis — for example, a complex mixed-use rehabilitation, an archaeological discovery during construction, or a sustainability upgrade with potentially conflicting preservation values — the underlying federal Standards and their accompanying Guidelines for Rehabilitating Historic Buildings provide the more detailed framework staff and the HPOZ Board may consult.

The Standards inform several specific procedural moments in HPOZ review. They are rarely cited by name in Letters of Determination, but they shape the analysis behind the determination.

COA review on Contributing structures applies design guidelines that descend from the Standards. The Plan-specific guidelines control where more specific, but the underlying logic — repair before replacement, in-kind matching, no conjectural restoration, additions clearly distinguishable yet compatible — comes from the Standards.

The Survey’s Contributing-Altered classification depends on whether alterations are “deemed reversible.” Reversibility is a Standards concept: alterations that can be undone without further damaging historic fabric retain Contributing status; alterations that cannot be undone without damage push a structure to Non-Contributing. The classification framework is built on the Standards’ treatment hierarchy.

The citywide ordinance includes an Exempt Work category for work required to comply with the Secretary of the Interior’s Standards (or with the Building Code, Rent Stabilization Ordinance, Housing Code, or other applicable laws), where the compliance could not reasonably have been achieved through Maintenance and Repair. Work qualifying under this exemption is brought to the Department of City Planning for verification before proceeding. The pathway is narrow and verification-dependent, but it exists, and it is one of the few places the citywide ordinance names the Standards directly.

Source: Secretary of the Interior’s Standards for the Treatment of Historic Properties (36 CFR Part 68, promulgated 1995, replacing the 1978 and 1983 versions). Standards for Rehabilitation (36 CFR Part 67, promulgated 1990). Standards published by the National Park Service, Technical Preservation Services (nps.gov/orgs/1739/secretary-standards-treatment-historic-properties.htm). LA HPOZ Preservation Plan citation language, the foundation-with-override hierarchy, and the six derived principles drawn directly from adopted Preservation Plans across the LA HPOZ system. The Exempt Work pathway tied to compliance with the Standards is set in the citywide HPOZ Ordinance (LAMC §12.20.3).