<photo>Detail of window arches above a rehabilitated storefront;  Link to National Park Service
<photo>detail of historic building with compatible new addition

Although the work in these sections is quite often an important aspect of rehabilitation projects, it is usually not part of the overall process of preserving character-defining features (maintenance, repair, replacement); rather, such work is assessed for its potential negative impact on the building's historic character. For this reason, particular care must be taken not to obscure, radically change, damage, or destroy character-defining features in the process of rehabilitation work.

Placing functions and services required for the new use in non-character-defining interior spaces rather than constructing a new addition.

Constructing a new addition so that there is the least possible loss of historic materials and so that character-defining features are not obscured, damaged, or destroyed.

photo of compatible new library addition on a prominent downtown Chicago library

This downtown Chicago library was expanded in 1981 when additional space was required with light and humidity control for the rare book collection. The compatible 10-story wing was linked to the historic block on side and rear elevations. Its simple design is compatible with the historic form, features, and detailing; old and new are clearly differentiated. Photo: Dave Clifton.

Designing a new addition in a manner that makes clear what is historic and what is new.

Considering the design for an attached exterior addition in terms of its relationship to the historic building as well as the historic district or neighborhood. Design for the new work may be contemporary or may reference design motifs from the historic building. In either case, it should always be clearly differentiated from the historic building and be compatible in terms of mass, materials, relationship of solids to voids, and color.

photos of two historic buildings that were successfully  joined during rehabilitation by a small glass connector addition

As part of this rehabilitation, two historic buildings were successfully joined by a new addition. The small glass connector between the two buildings (see photo, right) is appropriately set back. Photo: Martha L. Werenfels, AIA.

Placing a new addition on a non-character-defining elevation and limiting the size and scale in relationship to the historic building.

Designing a rooftop addition when required for the new use, that is set back from the wall plane and as inconspicuous as possible when viewed from the street.

Not Recommended
Expanding the size of the historic building by constructing a new addition when the new use could be met by altering non-character-defining interior spaces.

Attaching a new addition so that the character-defining features of the historic building are obscured, damaged, or destroyed.

Duplicating the exact form, material, style, and detailing of the historic building in a new addition so that the new work appears to be part of the historic building.Imitating a historic style or period of architecture in a new addition.

photo of a highly visible new rooftop addition that is also replicative in design; it does not meet the Standards for Rehabilitation

This highly visible new rooftop addition appears to be part of the historic building because of its replicative design and historicized detailing, such as the arched windows. This approach does not meet the Standards for Rehabilitation. Photo: NPS files.

Designing and constructing new additions that result in the diminution or loss of the historic character of the resource, including its design, materials, workmanship, location, or setting.

Designing a new addition that obscures, damages, or destroys character-defining features of the historic building.

Constructing a rooftop addition so that the historic appearance of the building is radically changed.


The Approach

Exterior Materials
Architectural Metals

Exterior Features
Entrances + Porches

Interior Features
Structural System Spaces/Features/Finishes
Mechanical Systems



Special Requirements
Energy Efficiency
New Additions
Health + Safety

The Standards



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Historical Overview