What Should You Expect From Historic Roof Restoration?

Documentation opens a historic restoration by photographing, measuring, and recording the existing roof — its patterning, coursing, color variation, and material dimensions — so the work matches the original, per NPS Preservation Brief 4. Recording the existing roof before any removal captures the historic detailing that the finished restoration reproduces, and physical samples taken from unweathered areas set the reference for matching replacement material.

Historic Preservation Commission approval runs separately from the construction permit, because a designated landmark or a contributing property in a local historic district requires a Certificate of Appropriateness under N.J.S.A. 40:55D-107 before exterior roof work begins. The Certificate of Appropriateness is issued by the municipal Historic Preservation Commission, while a construction permit is issued under the NJ Uniform Construction Code, and a reroof in a local district commonly requires both. A National or New Jersey Register listing alone places no restriction on a private owner using private funds, per the National Park Service and the NJ DEP Historic Preservation Office, so the binding gate is the local ordinance and its Certificate of Appropriateness.

The Secretary of the Interior's Standards guide the Historic Preservation Commission's decision, directing that deteriorated original features be repaired rather than replaced and that any replacement match the old in design, color, texture, and, where possible, material, per Standard 6. Review timelines vary by municipality, so the schedule depends on the local commission's calendar and the completeness of the documentation submitted with the application.

Period-accurate material is matched to the original by quarry for slate, by alloy for metal, and by species for wood shingle, then sourced from suppliers and salvage yards that stock reclaimed slate and copper. Matching the source matters because natural slate carries color, thickness, and texture tied to its quarry, and the finished restoration reproduces that appearance, per the Secretary of the Interior's Standards, Standard 6, and the National Slate Association.

Compatible substitutes enter only where the original material is unavailable, and the Historic Preservation Commission decides what it accepts, allowing synthetic slate on some non-contributing structures while individually designated landmarks typically require natural material. The commission weighs the substitute against the historic appearance, so a substitute that reads identically from the street can clear review on a less-sensitive building while a landmark holds to the original material.

Fasteners are non-ferrous on slate and clay tile — solid copper or stainless steel — because plain and galvanized steel rust out long before the slate, per NPS Preservation Brief 29. Red cedar, by contrast, never takes copper, since a chemical reaction between cedar and copper shortens the roof life, so cedar fastens with hot-dipped zinc-coated, aluminum, or stainless steel nails, per NPS Preservation Briefs 19 and 30.

The restoration proceeds in sections, with salvageable original material sounded and sorted for reinstallation and new material integrated with the existing surface rather than tearing off the whole roof. Working in sections lets the crew reuse sound slates and tiles and replace only failed elements in kind, per NPS Preservation Brief 29 and the Secretary of the Interior's Standards, Standard 6, keeping as much original fabric on the building as possible.

Flashing is fabricated in period-appropriate metals — copper or lead-coated copper — formed to match the original profiles, because flashing carries a life comparable to the slate it serves, per NPS Preservation Brief 29. Matching the historic flashing profile keeps the restored detail consistent with the building's character, and the completed work is documented so the record matches the pre-restoration survey. A historic roof restoration reproduces these details rather than substituting a modern profile.

The crew does not walk directly on slate or high-profile clay tile, because foot traffic cracks the brittle units, per NPS Preservation Briefs 29 and 30. Roof jacks, ladders, and staging boards distribute weight off the historic surface, protecting the original material that the restoration is working to retain.