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

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.

Masonry/Wood/Architectural Metals

Installing thermal insulation in attics and in unheated cellars and crawlspaces to increase the efficiency of the existing mechanical systems.

Installing insulating material on the inside of masonry walls to increase energy efficiency where there is no character-defining interior molding around the windows or other interior architectural detailing.

Not Recommended
Applying thermal insulation with a high moisture content in wall cavities which may damage historic fabric.

Installing wall insulation without considering its effect on interior molding or other architectural detailing.

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Utilizing the inherent energy conserving features of a building by maintaining windows and louvered blinds in good operable condition for natural ventilation.

Improving thermal efficiency with weatherstripping, storm windows, caulking, interior shades, and if historically appropriate, blinds and awnings.

photo showing deteriorated historic steel window units (left) and matching custom-made replacement units (right)

The historic steel window units (left) were in an advanced state of deterioration before rehabilitation. Following a thorough window assessment, they were replaced with custom-made units which matched the configuration, profile, and color of the existing windows and greatly improved the thermal performance. Photos: NPS files.

Installing interior storm windows with air-tight gaskets, ventilating holes, and/or removable clips to ensure proper maintenance and to avoid condensation damage to historic windows.

Installing exterior storm windows which do not damage or obscure the windows and frames.

Not Recommended
Removing historic shading devices rather than keeping them in an operable condition.

Replacing historic multi-paned sash with new thermal sash utilizing false muntins

photo showing inappropriate tinted glazing on a primary elevation

The historic windows (left) on a primary elevation were inappropriately replaced
with tinted glazing (right). Photo: Mike Jackson.

Installing interior storm windows that allow moisture to accumulate and damage the window.

Installing new exterior storm windows which are inappropriate in size or color.

Replacing windows or transoms with fixed thermal glazing or permitting windows and transoms to remain inoperable rather than utilizing them for their energy conserving potential.

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Entrances and Porches

Maintaining porches and double vestibule entrances so that they can retain heat or block the sun and provide natural ventilation.

photo showing how a porch can typically reduce heat gain from the sun

A porch typically reduces heat gain from the sun. Photo: NPS files.

Not Recommended
Changing the historic appearance of the building by enclosing porches.

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Interior Features

Retaining historic interior shutters and transoms for their inherent energy conserving features.

Not Recommended
Removing historic interior features which play an energy conserving role.

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Mechanical Systems

Improving energy efficiency of existing mechanical systems by installing insulation in attics and basements.

Not Recommended
Replacing existing mechanical systems that could be repaired for continued use.

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Building Site

Retaining plant materials, trees, and landscape features which perform passive solar energy functions such as sun shading and wind breaks

photos showing trees that were planted to shade a portion of the Olmsted National Historic Site.

These trees were planted to shade the historic property. Photo: Courtesy, Olmsted

Not Recommended
Removing plant materials, trees, and landscape features that perform passive solar energy functions.

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Setting (District/Neighborhood)

Maintaining those existing landscape features which moderate the effects of the climate on the setting such as deciduous trees, evergreen wind-blocks, and lakes or ponds.

Not Recommended
Stripping the setting of landscape features and landforms so that effects of the wind, rain, and sun result in accelerated deterioration of the historic building.

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New Additions to Historic Buildings

Placing a new addition that may be necessary to increase energy efficiency on non-character-defining elevations.

Not Recommended
Designing a new addition which obscures, damages, or destroys character-defining features.

photo showing highly visible (inappropriate) new skylights on the front and back of a historic building

These new skylights on the front and back of the historic building altered its character from several views in the hilly district. Buildings that have prominent roofs or highly visible roof elevations are usually not good candidates for skylights. Photos: NPS files.



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