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Guidelines on Flood Adaptation for Rehabilitating Historic Buildings

Greek Revival house Greek Revival house after flood adaptation
This Greek Revival house sits close to the ground, with little visible foundation. A 2011 flood inundated the first floor (photo below). The house was substantially elevated to reduce future flood risk.
The house was raised on a new foundation with flood vents, and a change in the stair design and materials breaks the stairs into two smaller runs. Plantings and new fill also help disguise the change in height.
Greek Revival house in a flood.
All photos courtesy of Julie Nucci and James Overhiser, Owego, New York

Flooding risk has long been a major challenge for many historic properties. Changing weather patterns, stronger hurricanes and other extreme weather events, sea level rise, increased nuisance flooding, king tides, and continuing development in floodplains are some of the factors increasing the risk of flooding events, both in terms of their frequency and magnitude. Some historic properties that have never flooded before may now be exposed to this risk, and those that flooded infrequently in the past may experience more instances of flooding or of water reaching higher levels than ever before.

The goal of the Guidelines on Flood Adaptation for Rehabilitating Historic Buildings is to provide information about how to adapt historic buildings to be more resilient to flooding risk in a manner that will preserve their historic character and that will meet The Secretary of the Interior’s Standards for Rehabilitation. These guidelines should be used in conjunction with the Guidelines for Rehabilitating Historic Buildings that are part of The Secretary of the Interior’s Standards for the Treatment of Historic Properties with Guidelines for Preserving, Rehabilitating, Restoring & Reconstructing Historic Buildings. Like the Guidelines for Rehabilitating Historic Buildings , these guidelines are intended to focus primarily on historic buildings and their site and setting.

The treatments described in the Guidelines may be considered as means for preserving historic properties located in floodplains and making them more resilient to flooding hazards. While many of these treatments can be undertaken with minimal effects on the historic character of a property, some may require more change than would normally be acceptable in other contexts. Consequently, only buildings with a demonstrable risk of flooding should be using the adaptive treatments described in the Guidelines. Adaptation treatments should reduce the risk of flood damage as much as possible, but should do so without destroying significant historic materials, features, or spaces.

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Watch this introductory webinar to learn why the National Park Service developed the Guidelines and how you can use them.

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FAQs - Flooding Adaptation, Climate Change & Sustainability

Flooding risk has long been a major challenge for many historic properties. Changing weather patterns, stronger hurricanes, other extreme weather events, sea level rise, nuisance flooding, king tides, and continuing development in floodplains are some of the causes of flooding. Flooding events are occurring at increased frequency and magnitude. Some historic properties that have never flooded before may now be exposed to this risk, and those that flooded infrequently in the past may experience more instances of flooding or of water reaching higher levels than ever before.

The Guidelines on Flood Adaptation provide information about how to adapt historic buildings to be more resilient to flooding risk in a manner that preserves their historic character. In this context, resilience means the capacity of a historic property to withstand and recover from a flooding event. These Guidelines were developed to help guide flood adaptation projects to make a building more resilient to flooding while meeting The Secretary of the Interior’s Standards for Rehabilitation and preserving the property’s historic features, spaces, materials, site, and setting. 

The Guidelines were specifically developed as a means of preserving historic buildings located in flood-prone areas and making them more resilient to flooding hazards. Flood events can be particularly destructive to historic buildings and therefore may require greater adaptive treatments. While many of these treatments can be undertaken with minimal effects on the historic character of a property, some may require more change than would normally be acceptable in other contexts in order to address the flooding risk and help ensure the continued preservation of the property. 

Achieving greater resilience and reducing flood risk must be balanced with economic and technical feasibility while minimizing the impacts to the historic character of the building. These Guidelines are designed to help identify and evaluate the different adaptation options in order to select a treatment that preserves the historic character, site, and setting of the historic building.

The Guidelines on Flood Adaptation were developed for historic properties with an established risk of flooding. They can be used by property owners of historic buildings, design and construction professionals, Federal, state, and local agencies, local planning and preservation commissions, non-profit organizations, real estate professionals, and the general public. Local communities may also wish to use these Guidelines to develop their own set of guidelines tailored to the characteristics of their own historic properties and flood adaptation plans.  

While the Guidelines were specifically developed for use with historic buildings, property owners of any existing building may find the Guidelines useful in understating how to adapt their buildings to be more resilient to flooding.   

The Guidelines provide a basis for how to adapt historic buildings to be more resilient to flooding risk in a manner that preserves their historic character. Because every historic property and flood adaptation project is different, the Guidelines discuss different approaches to making a property more resilient to flooding and provide a framework to evaluate the different impacts of such treatments on the historic character of the historic building. 

The impacts of the different adaptation treatments will vary greatly depending on multiple factors such as location and site conditions of a property, historic significance, flood risk, physical and structural attributes, and its features, materials, and architectural style. For example, elevating a building on a new foundation 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. 

The purpose of the Guidelines is to help guide adaptation projects to make a building more resilient to flooding risks while minimizing the impacts to its historic character, site, and setting. These Guidelines are intended to assist property owners undertaking a flooding adaptation project, recognizing that, as with any rehabilitation project, there are always other design, programmatic, financial, and regulatory requirements that must also be considered in planning such projects. 

The Secretary of the Interior’s Standards for Rehabilitation were developed to help guide work undertaken on a historic property to meet continuing or changing needs or uses while retaining the property's historic character. The ten Standards are a series of basic principles about maintaining, repairing, and replacing historic features and materials, as well as designing new additions or making alterations. The Standards are inherently flexible in order to apply to historic properties of all types, materials, construction, sizes, and use and are to be applied in a reasonable manner, taking into account economic and technical feasibility.

Guidelines like the Guidelines on Flood Adaptation offer general design and technical recommendations to assist in applying the Standards for Rehabilitation to a specific property. The Guidelines give more detailed, best-practice advice, specific to the types of alterations and changes necessary to make a historic property more resilient to flooding risk consistent with the Standards. Together, the Standards and the Guidelines provide a framework and guidance for decision-making about work or changes to a historic property. 

The Guidelines on Flood Adaptation are designed to help identify and evaluate the different adaptation options in order to select a treatment that meets the Standards for Rehabilitation. Wherever possible, the Guidelines provide “Recommended” methods of implementing each type of adaptation in order to preserve as much of the historic character of a building and its site and setting as possible. However, the Standards and Guidelines should be applied on a “cumulative effect basis”: a project meets the Standards when the overall effect of all work on the property is one of consistency with the property’s historic character, and not necessarily based on the effects of an individual treatment or treatments.

In addition to the Guidelines on Flood Adaptation, the NPS has issued a more general, comprehensive set of Guidelines for Preserving, Rehabilitating, Restoring, & Reconstruction Historic Buildings, corresponding with the four sets of the Secretary of the Interior’s Standards for the Treatment of Historic Properties. The NPS has also issued a separate set of Guidelines, the Guidelines on Sustainability, focused on how to make historic buildings more energy efficient and sustainable. The Guidelines on Sustainability are part of the larger four-treatment set of guidelines.   

Last updated: June 8, 2021