Secretary of the Interior's Standards for Rehabilitation: A Bay Area Homeowner's Guide

If your Bay Area home sits in a historic district or is individually listed on a local historic resources inventory, any exterior change you propose will be measured against a single federal framework: the Secretary of the Interior’s Standards for Rehabilitation. These 10 principles, originally developed by the National Park Service in the 1970s and revised in 1990, are the yardstick that cities from San Jose to San Francisco use when deciding whether your project gets approved or sent back for redesign.

Understanding these Standards before you start drawing plans can save months of revision cycles. This guide breaks them down in plain English, explains which ones trip up residential projects most often, and shows how four Bay Area cities apply them in practice.

What Are the Secretary of the Interior’s Standards for Rehabilitation?

The Standards for Rehabilitation are 10 principles published by the U.S. Department of the Interior through the National Park Service. They are codified in the Code of Federal Regulations at 36 CFR Part 67 (for the Federal Historic Preservation Tax Incentives program) and 36 CFR Part 68 (for the broader Treatment of Historic Properties framework).

Their origin traces back to the Tax Reform Act of 1976, when Congress sought to encourage the rehabilitation of historic buildings rather than their demolition. The National Park Service drafted the first version of the Standards in the late 1970s, then revised them in 1990 into the 10-standard format still in use today.

While the Standards were created for federal tax credit projects, their influence extends far beyond that program. Most local historic preservation commissions across the country have adopted them as the criteria for reviewing Certificates of Appropriateness and historic preservation permits. In the Bay Area, San Jose, Redwood City, Palo Alto, and San Francisco all reference these Standards when evaluating proposed changes to historic properties.

The core idea is straightforward: you can update a historic building for modern life, but you must preserve the materials and features that make it historically significant.

The 10 Standards in Plain English

Here is each Standard distilled for residential projects.

Standard 1: Use. Keep the property in its historic use (as a home) or adapt it to a new use that requires minimal change to its defining features.

Standard 2: Historic character. Preserve the building’s historic character. Do not remove or alter features and materials that define it.

Standard 3: No false history. Do not add features from other periods or styles that create a misleading impression of the building’s history. If your 1920s Craftsman never had Victorian gingerbread trim, do not add it now.

Standard 4: Respect later changes. Alterations made over the decades may have become historically significant in their own right. A 1940s porch addition on an 1890s Queen Anne may now be part of the building’s story.

Standard 5: Preserve distinctive features. Protect original finishes, construction techniques, and craftsmanship. Original wood windows, decorative brackets, and shingle patterns all fall here.

Standard 6: Repair before replacing. Fix deteriorated features rather than replacing them. When replacement is unavoidable, the new feature must match the original in design, color, texture, and (where possible) materials. Document the original before removing it.

Standard 7: No damaging treatments. Do not use chemical or physical treatments (such as sandblasting masonry) that damage historic materials.

Standard 8: Protect archaeological resources. If your project disturbs the ground, protect and preserve any significant archaeological resources on site.

Standard 9: New work must be compatible and differentiated. New additions and exterior alterations must not destroy historic materials. New work must be compatible with the historic building in massing, size, scale, and architectural features, yet clearly differentiated from the original construction.

Standard 10: Reversibility. New additions and related new construction must be designed so that if removed in the future, the essential form and integrity of the historic property remains unimpaired.

Standards 9 and 10: The Two That Matter Most for Residential Projects

For homeowners planning additions, window changes, dormers, or ADUs on a historic property, Standards 9 and 10 are where most review conversations begin and most disputes arise.

Standard 9 sets up a deliberate tension. Your new work must be compatible with the historic building: it should respect the original structure’s scale, proportions, and massing. At the same time, it must be differentiated from the old. The addition should read as a product of its own time, not as a fake extension of the original.

What does this look like in practice? A compatible addition might use similar roof pitch and eave height but employ a slightly different material palette or simplified detailing. There is no single formula. A new addition can be traditional, contemporary, or a simplified interpretation of the historic building. What it cannot be is an exact replica that blurs the line between old and new, or a wildly contrasting design that overpowers the original.

Standard 10 requires that your addition be reversible. If someone were to remove it decades from now, the historic building underneath should still be intact. This means additions typically connect at limited points, avoid demolishing original walls where possible, and use construction methods that do not permanently alter the historic structure.

These two Standards are what most commonly trip up homeowners proposing new additions or exterior modifications. A second-story dormer that changes the roofline’s historic profile, replacement windows that do not match the originals in proportion and operation, or a rear addition whose mass dwarfs the original cottage: all of these can trigger denial under Standards 9 and 10.

How Bay Area Cities Use These Standards

Each Bay Area city supplements the federal Standards with its own local guidelines and review process. Here is how four of the most active preservation programs work.

San Jose

San Jose’s Historic Landmarks Commission (HLC) reviews projects on properties listed in the City’s Historic Resources Inventory. The HLC evaluates proposals against both the Secretary of the Interior’s Standards for Rehabilitation and the city’s own design guidelines document, Your Old House: Guide for Preserving San Jose Homes. The Commission holds a public hearing, considers evidence and public comment, and makes a recommendation to the Planning Director. For more detail on San Jose’s permit process, see our guide to historic preservation permits in San Jose.

Redwood City

Redwood City routes historic property reviews through its Planning Division, which may commission a conformance evaluation from a qualified preservation consultant. The consultant prepares a memo assessing the proposed work against the Secretary of the Interior’s Standards, then works with the project architect to identify modifications that would improve conformance. This collaborative, memo-driven approach can help projects reach approval before they ever reach a public hearing.

Palo Alto

Palo Alto’s Historic Resources Board (HRB) reviews projects involving properties on the city’s historic inventory. In the Professorville Historic District, the city adopted dedicated design guidelines in 2016 that are closely based on the Secretary of the Interior’s Standards. Properties classified as Group A resources require review against the Standards for discretionary applications including Individual Review and two-story home review. Notably, Professorville review can extend to interior work and landscaping, which is unusual among Bay Area cities.

San Francisco

San Francisco’s Historic Preservation Commission (HPC), established in 2008, reviews proposed work on designated landmarks and properties within historic districts. The HPC must find that proposed work complies with the Secretary of the Interior’s Standards, the designating ordinance, and any applicable local guidelines.

A shared benefit across all four cities: in California, projects that conform to the Secretary of the Interior’s Standards may qualify for a Class 31 categorical exemption under the California Environmental Quality Act (CEQA). This exemption covers rehabilitation work done consistently with the Standards, which can significantly streamline the environmental review process.

”Your Old House”: San Jose’s Local Companion Resource

San Jose’s Your Old House: Guide for Preserving San Jose Homes deserves special attention because it translates the federal Standards into residential terms specific to San Jose’s housing stock. The guide addresses common housing types found in the city’s historic districts, from Victorian-era cottages to mid-century ranch homes.

The Historic Landmarks Commission uses this document alongside the Secretary of the Interior’s Standards as the basis for reviewing Historic Preservation Permits. While the federal Standards provide the broad principles, Your Old House offers practical, illustrated guidance on topics like appropriate window replacement profiles, porch repair techniques, and compatible addition design for San Jose’s particular architectural context.

If your home is listed on San Jose’s Historic Resources Inventory, reading this guide before you begin your design is one of the most productive steps you can take.

Common Mistakes That Get Applications Denied

Based on how these Standards are applied in Bay Area review processes, certain patterns lead to denial more often than others.

Replacing original materials unnecessarily. Standard 6 requires repair before replacement. Proposing to tear out original wood windows and install vinyl replacements, when the originals could be restored, is one of the fastest ways to receive a denial.

Additions that overpower the original structure. Standard 9 requires compatibility in massing, size, and scale. A two-story addition on a single-story bungalow that doubles the building’s footprint will raise immediate red flags.

Failing to differentiate new from old. The opposite problem: designing an addition that perfectly mimics the original so that the building appears to have always been that size. Standard 3 prohibits creating a false sense of historical development, and Standard 9 requires differentiation.

Ignoring the streetscape context. The Standards protect the historic property “and its environment.” An addition that may be compatible with the house itself but disrupts the visual rhythm of a historic streetscape can still fail review.

Submitting without adequate documentation. Applications that lack historical photographs, material specifications, or a clear explanation of how each Standard is addressed force reviewers to assume the worst. 3D renderings and visual documentation can make a significant difference in how clearly your project communicates compliance.

How to Design Your Project for SOIS Compliance

Designing for Standards compliance does not mean freezing your home in time. It means approaching changes with intention and evidence.

Start with research. Before sketching a single line, document what you have. Photograph every exterior elevation. Identify original materials versus later alterations. Pull any available historic photos from local archives or your city’s planning files.

Hire a preservation-qualified architect. Not every architect has experience with the Secretary of the Interior’s Standards. A preservation architect or one experienced with historic district projects in your area will understand how to balance your goals with the Standards from the first design meeting.

Address each Standard explicitly. When preparing your application, walk through all 10 Standards and explain how your project meets each one. Review bodies look for this level of specificity.

Use the pre-application process. Most Bay Area cities offer informal staff consultations before you file a formal application. In San Jose, staff can flag potential conflicts with the Standards early, when changes are cheap to make. Take advantage of this.

Consider the “reversibility test” for every design decision. For each proposed change, ask: if this were removed in 50 years, would the original building still be intact underneath? If the answer is no, redesign that element.

Invest in quality visual communication. Review commissions evaluate projects from drawings and renderings. High-quality 3D visualizations that show the proposed changes in context, alongside the existing building and neighboring properties, help reviewers see what you see.

Working with a design-build team that understands both the regulatory framework and the construction realities of historic homes can streamline this process significantly. If you are planning changes to a historic property in the Bay Area and want to discuss your project’s feasibility, reach out to our team for an initial conversation.