The Secretary of the Interior Standards
The Secretary of the Interior Standards govern the kind of adaptive reuse Michael Stern’s firm says it is drawn to, work that sets an old building and a new one in tension rather than dressing the new in borrowed history, and the people who apply them are not in Washington. One of them was on a scaffold over Times Square. Building Design + Construction recounts the restoration of the Candler Building, a 1912 white terra cotta tower whose skin was failing, and the moment the team chose cast stone, coated to resemble the original, for the pieces that could not be saved.1 The choice was not only about cost. Because the building was listed on the National Register, the standards required that new material match the original in appearance and yet remain identifiable as new to a future restorer, and the consultant, a Columbia preservation professor, called that similar but different mandate a benefit in this case, since matching a century old fired glaze exactly would have been next to impossible anyway.1 That is the standards at work: ten sentences that decide, on a scaffold, what the next hundred years of a wall will be made of.
The text and the hands that use it
The sentences themselves are short. The National Park Service publishes the Standards for Rehabilitation, codified at 36 CFR Part 67, as the regulatory test for the federal historic preservation tax incentives and as the text most often used by local historic district commissions across the country.8 They ask that a property keep its historic use or take a new one that needs minimal change to its defining features; that historic character be retained and later changes that have earned significance kept; that nothing conjectural be added; that deteriorated features be repaired in preference to replacement, and matched on evidence where replacement is unavoidable; that cleaning be done by the gentlest means; and, in the two standards that govern additions, that new work be told apart from the old while remaining compatible with its mass, size, scale and features, and be built so that its removal would leave the historic property unimpaired.8 The Park Service adds that the standards are to be applied in a reasonable manner, taking economic and technical feasibility into account, and that the accompanying Guidelines cannot tell an owner which features matter in a particular building; that judgment belongs to qualified preservation professionals brought in while the project is still being planned.8
The ten standards, grouped
- UseKeep the historic use or find one that needs minimal change to the defining features and site.
- CharacterRetain historic character; avoid removing materials or altering spaces that define it; keep later changes that have earned significance; add nothing conjectural.
- RepairRepair deteriorated features rather than replace them; where replacement is unavoidable, match design, colour, texture and if possible material, on evidence.
- TreatmentUse the gentlest cleaning that works; no sandblasting or treatments that damage historic material; protect archaeology.
- New workAdditions must not destroy historic material, must read as new while fitting the mass, size and scale of the old, and must be removable without impairing the historic property.
The makers, then, are the architects, conservators and tradespeople who translate the ten sentences into a drawing or a mortar mix. The window restorers at Austin Historical describe working to the Park Service’s Preservation Brief 9 under the Interior Department standards, and make the point that the brief is a field guide rather than a philosophy: most historic wooden windows can be repaired, replacement should follow an assessment rather than precede it, and performance upgrades such as weatherstripping and storm sashes are allowed, which matters because replacement is so often justified on energy claims that never considered repair.3 The briefs run to fifty. The Historic Preservation Education Foundation offers continuing education credit to architects who read Brief 17, on identifying the visual aspects of a building that define its character, which is the step the standards assume has been done before any of the ten is applied.7
The field the makers work in is reflecting on its own text. A series of roundtables at the University of Pennsylvania’s Stuart Weitzman School of Design in 2023 and 2024 set the modern framework, the Venice Charter and the National Historic Preservation Act among its foundations, against the pressures of climate and a market that preservation has embraced and must also resist, and heard designers describe caring for aging buildings as a problem of managing change for the health of a whole district rather than freezing a single object.6 The standards are not revised by such conversations, but the professionals who apply them are shaped by them, and the fourth standard, which protects changes that have acquired significance, is already an instruction to read a building as a record of time rather than a design to be returned to.
The credit and the reviewer
The second place the standards are applied is a desk. The federal tax incentive turns on a certified rehabilitation, and the Park Service states the test plainly: the work must be determined by the Secretary to be consistent with the historic character of the structure and, where applicable, of the district, and the standards encompass the exterior, the interior, the site and any attached or related new construction.8 That reach is wider than a city designation’s. 6sqft draws the contrast for New York owners: listing on the National Register is largely honorific and leaves an owner free to alter the property, but it opens access to credits and grants that have turned old factories into housing and revived historic downtowns, and those credits come with the federal review attached.2 Village Preservation adds the eligibility threshold, generally 50 years, and notes that owners of listed properties may claim federal investment tax credits for rehabilitation.5
Two reviews of the same wall
| City landmark review | Federal tax credit review | |
|---|---|---|
| Trigger | Designation by the city | Listing on or eligibility for the National Register |
| Text applied | The report that designated it, plus the Commission's rules | The ten Standards for Rehabilitation and their Guidelines |
| Decision | A permit or a hearing | Certification that the work is consistent with historic character |
| Interior reach | Only a designated interior | The whole building, inside and out |
| What a miss costs | No permit | No credit |
For an owner the two reviews can run at once. A townhouse owner interviewed by Brick Underground describes obtaining her Landmarks approvals in stages over several years, and the same piece notes that credits, and grants from the New York Landmarks Conservancy, are available for architecturally significant rehabilitation, which is to say the city permit and the federal certification can be sought for one project.4 What the applicant shows the reviewer is the same thing the Candler team showed: an assessment of which features define the building, evidence for every replacement, and new work that a future restorer can tell apart from the old and take away without harm. The designation reports entry draws the line between the city’s text and the federal nomination; the entries on facade retention and masonry show the standards’ sixth and ninth sentences carried out in steel, brick and clay.
