The following guidance is adapted from the “Resilience to Natural Hazards” section (p.24) in The Secretary of the Interior’s Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring and Reconstructing Historic Buildings (2017) and from The Guidelines on Flood Adaptation for Rehabilitating Historic Buildings (2021).
For more contextual and detailed information and discussion of this topic and the terminology used, please consult these two publications. The Treatment Guidelines also include a “Resilience to Natural Hazards” section with recommended and not recommended work in each of the four sets of treatment guidelines.
Resilience to Natural Hazards
The potential future impacts of natural hazards on a historic building should be carefully evaluated and considered. If foreseeable loss, damage, or destruction to the building or its features can be reasonably anticipated, treatments should be proactively undertaken to avoid or minimize the impacts and to ensure the continued preservation of the building and its historic character. In other instances, the effects may be minimal or more gradual and the impacts unknown or not anticipated to affect the property until some future time, but they should still be considered. In all instances, an historic building should be maintained in good condition and monitored regularly, and historic documentation should be prepared as a record of the building and to help guide future treatments.
Some impacts of natural hazards may be particularly sudden and destructive to a historic building (such as riverine flash flooding, coastal storm surge, earthquakes, or tornadoes) and may require adaptive treatments that are more invasive than would be acceptable in other contexts.
When an adaptive treatment is proposed that would significantly affect the building’s historic character, feasible alternatives that require less change should always be considered first. Many treatments can be undertaken with minimal effects on the historic character of a property.
In other instances, a greater degree of impact on a building’s historic character may be necessary to ensure its retention and continued preservation. Such treatments may be acceptable in the context of making an historic building more resilient to natural hazards than would generally be acceptable in other contexts. Achieving greater resilience must likewise be balanced with economic and technical feasibility while minimizing the impacts to the historic character of the building.
An historic building may have existing characteristics or features that help to address or minimize the impacts of natural hazards. Some historic buildings may also have been altered previously or be in regions where it has been traditional to adapt buildings frequently subject to damage from natural hazards, such as flooding.
All these factors should be taken into consideration when planning adaptive treatments. The goal—the “intersection” in the diagram above—should always be to adapt the historic building to be more resilient to natural hazards while maintaining its historic character and avoiding destroying distinctive historic materials, features, and spaces.
Planning and Assessment to Reduce Risk
The Guidelines on Flood Adaptation for Rehabilitating Historic Buildings, while developed specifically in response to flood risk, provide a framework that can be adapted for use in the planning, assessment, and evaluation of risks for other types of natural hazards as well as recommended and not recommended actions. See the Flood Adaptation Guidelines for more detailed information and definitions of the terminology used.
The impacts of adaptation treatments to an historic building will vary greatly depending on multiple factors such as location and site conditions of a property, historic significance, the natural hazard(s) and type of risk(s), physical and structural attributes, and the building’s historic features, materials, and architectural style. For example, elevating a building on a new foundation to address flood risk may have a minimal impact on one building’s historic character, yet for another property the same treatment may change the building’s historic character significantly and not meet the Secretary of the Interior’s Standards. Selecting more than one treatment or combining treatment approaches may also be necessary to make the building more resilient and/or to minimize the impacts to the historic character and appearance of the property.
Before undertaking any work to adapt an historic building to be more resilient to potential natural hazards, research about the actual risks and the nature of the risks as well as about the historic property itself must be undertaken. Proposed alterations to adapt the property will need to be adequate to address the identified risks. As with any rehabilitation project, there are also always other design, programmatic, financial, and regulatory requirements that must also be considered in planning such work, including applicable Federal, state, and local code requirements and regulations.
Prior to undertaking any work, the property’s historic spaces, features, materials, and finishes affected by the natural hazards or the proposed adaptive treatment should be documented. The property’s existing capacity to sustain and recover from the natural hazards, as well as its physical condition and use, should be evaluated. Those spaces, features, and materials that are important to the historic character and significance of the property should be identified for retention and preservation. Existing materials and features that already provide resiliency may also be considered for retention, improvement, or enhancement. In regions where buildings were historically adapted to address natural hazards such as frequent flooding, traditional treatment approaches should be learned from and considered.
All planning and assessment for reducing risks to natural hazards should include the following, which are further discussed in the Flood Adaptation Guidelines:
- Identify the historic property’s risks and vulnerabilities to natural hazards and any existing capacity for resilience.
- Monitor the condition of the property and regularly reevaluate its risks and vulnerabilities to natural hazards.
- Document the historic property. Preservation Brief 43: Preparation and Use of Historic Structure Reports can serve as a guide.
- Review and understand any Federal, state, and local compliance requirements and regulations.
- Identify and assess all feasible adaptation treatment options to determine how they will address the identified risks.
- For each treatment option, evaluate the impacts of any potential alterations to the historic property’s character-defining spaces, features, and materials, and its site and environment. See Identifying Primary and Secondary Interior Spaces in Historic Buildings, Preservation Brief 17: Architectural Character: Identifying the Visual Aspects of Historic Buildings as an Aid to Preserving their Character, Preservation Brief 18: Rehabilitating Interiors in Historic Buildings: Identifying and Preserving Character-Defining Elements, and other available information on character-defining features.
- Consideration should be given to how local communities have decided to adapt to the identified risks and natural hazards and treat historic properties impacted by these risks. Also consider the future viability of community infrastructure, such as roads, sewers, and other utilities and services.
- Select the time frame for which the adaptation treatment is expected to adequately reduce the risk. This could be tied to, e.g., the length of a mortgage or some other point in the future.
- Always select an adaptive treatment that minimizes the impacts to the historic character and appearance of an individual property as much as possible while making the property as resilient as possible.
Property owners of historic buildings should engage in active decision-making about how to adapt their historic buildings to be more resilient to the risks of natural hazards. Evaluation, documentation, and planning are critical for timely and purposeful decision-making. Factors including the severity and type of risk(s), economic and technical feasibility, and the historic character of the property should inform and be appropriately balanced in the decision-making process.
The decision should result in an adaptive treatment and implementation plan for the property or documentation explaining why no action is currently necessary along with a schedule for regular monitoring. Good stewardship requires making a choice.
April 2024
Last updated: April 12, 2024