Historic-preservation guidance aims to make Nantucket buildings more flood-resilient while protecting character

Holly Backus, Preservation Planner for the Town of Nantucket, told the Coastal Resilience Advisory Committee on May 27 that the town’s Resilient Nantucket design guidelines and toolkit translate federal guidance into island-specific recommendations so property owners and regulators can adapt historic buildings to rising seas without needlessly erasing character.

Why it matters: the entire island sits inside the local historic-district jurisdiction and a large share of structures were judged contributing through a period of significance extended to 1975; Backus said that requires balancing flood adaptation and preservation.

Backus described how the guidelines were developed from National Park Service and FEMA guidance and from local work under the state’s Municipal Vulnerability Preparedness (MVP) program. She said the Historic District Commission adopted Resilient Nantucket after multiple public meetings in June 2021 and that the documents are now available on the town website as both an illustrated design guidance manual and a property-owner toolkit.

“we are 1 of the largest historic districts in the nation,” Backus told the committee, noting the island’s early preservation work and National Historic Landmark designation.

The guidelines address a range of adaptation tactics for contributing historic resources (buildings constructed within the island’s period of significance), including lower-elevation compromises, wet- and dry-floodproofing strategies, relocation practices and choices for paving and permeability. Backus said the guidance recommends a reduced “design flood elevation” in some preservation-sensitive cases — for example, a 4-foot design elevation for certain contributing structures rather than the full, higher FEMA-required elevation — when combined with other mitigation measures intended to preserve a building’s defining features.

Backus and committee members stressed that the guidelines are advisory, not code: “The resilient Nantucket design guidelines is actually an addendum to Building With Nantucket in Mind,” she said, and noted that converting guidance into a bylaw or zoning requirement would require a separate process involving town bodies such as the Planning Board.

Committee members asked whether conflicts arise between preservation guidance and other regulatory programs that impose minimum flood elevations. Backus answered that exemptions that allow lower interventions apply only to contributing historic structures undergoing rehabilitations, not to new construction in flood zones, and said the HDC has approved projects at full FEMA elevation when applicants choose that route.

Several members asked for clearer, short-form outreach materials for property owners; Backus said a two-page Primer and the toolkit exist on the town website and that the illustrated guidelines are intentionally user-friendly with photos and diagrams. She also identified a specific planning area where the committee could help: limiting impervious surfaces. “Having an impervious calculation and trying to limit the amount of hardscaping, I think, would be helpful,” Backus said, pointing to the HDC’s material authority and the possibility of working with other boards to consider bylaw approaches to ground coverage and permeability.

Backus emphasized the overlap between hazard planning and preservation: Nantucket’s hazard mitigation plan (HMP) and its MVP action items both call for historic-resource integration and public education. The design guidelines were funded in part by an MVP action grant and developed with Preservation Institute Nantucket and consultants familiar with NPS/FEMA standards.

Action noted: the Historic District Commission formally adopted the Resilient Nantucket design guidelines in June 2021 after public meetings, and the toolkit and design manual are publicly posted on the town website for applicants, designers and homeowners.

What’s next: Backus recommended continued public education, more coordinated review with permitting boards, and potential collaboration with the committee on policy tools (for example, reduced impervious-surface bylaws) that would further resilience goals without undermining the district’s character.

Ending note: Committee members and staff thanked Backus for the presentation and agreed to use the guidelines in future outreach and review conversations so applicants see resilience and preservation as complementary concerns rather than competing requirements.