The National Park Service
Preservation Briefs:
A Practical Preservation Resource
Deborah Slaton, FAPT
Wiss, Janney, Elstner Associates, Inc.
This presentation includes:
ƒ An overview of the National Park Service, its effect on our
industry, and the resources NPS provides
ƒ An introduction to three resources provided by NPS:
ƒ The Secretary of the Interior’s Standards
ƒ The National Register Program
ƒ The Rehabilitation Tax Incentive Program
ƒ An overview of NPS publications, with special attention to the
Preservation Briefs – including examples of several briefs of special
interest to SWRI members, illustrated with examples (both good
and bad)
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The National Park Service
What is the U.S. National Park Service?
Founded in 1916, the US National Park Service is part of the Department
of the Interior. The National Park Service is the United States federal
agency that manages all national parks, many national monuments, and
other conservation and historical properties including historic trails, rivers,
lakeshores, seashores, and battlefields.
The National Park Service was created to "conserve the scenery and the
natural and historic objects and the wild life therein and to provide for the
enjoyment of the same in such manner and by such means as will leave
them unimpaired for the enjoyment of future generations."
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The Cultural Resources branch of the
National Park Service provides guidance in
the stewardship of the nation’s historic
buildings, landscapes, archeological sites,
ethnographic resources, objects and
documents, and structures and districts.
The goal of Cultural Resources programs is
to be sure that these heritage resources are
carefully identified, evaluated, documented,
registered, preserved, and interpreted.
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The Heritage Preservation Services division helps
individuals and communities identify, evaluate, protect and
preserve historic properties for future generations of
Americans. The division provides a broad range of products
and services, financial assistance and incentives,
educational guidance, and technical information in support
of this mission.
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The Secretary of the Interior’s
Standards
Secretary of the Interior's Standards - precepts published by
the National Park Service that provide guidelines for work on
preservation projects.
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The Secretary of the Interior’s Standards
for the Treatment of Historic Properties
The Secretary of the Interior’s Standards provide four distinct, but
interrelated, approaches to the treatment of historic properties.
ƒ Preservation focuses on the maintenance and repair of existing
historic materials and retention of a property’s form as it has evolved
over time.
ƒ Rehabilitation acknowledges the need to alter or add to a historic
property to meet continuing or changing uses while retaining the
property’s historic character.
ƒ Restoration is undertaken to depict a property at a particular period
of time in its history, while removing evidence of other periods.
ƒ Reconstruction re-creates vanished or non-surviving portions of a
property for interpretive purposes.
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Standards for Rehabilitation
1.
2.
3.
4.
5.
A property shall be used for its historic purpose or be placed in a new use that
requires minimal change to the defining characteristics of the building and its site and
environment.
The historic character of a property shall be retained and preserved. The removal of
historic materials or alteration of features and spaces that characterize a property
shall be avoided.
Each property shall be recognized as a physical record of its time, place, and use.
Changes that create a false sense of historical development, such as adding
conjectural features or architectural elements from other buildings, shall not be
undertaken.
Most properties change over time; those changes that have acquired historic
significance in their own right shall be retained and preserved.
Distinctive features, finishes, and construction techniques or examples of
craftsmanship that characterize a historic property shall be preserved.
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Standards for Rehabilitation (continued)
6.
Deteriorated historic features shall be repaired rather than replaced. Where the
severity of deterioration requires replacement of a distinctive feature, the new
feature shall match the old in design, color, texture, and other visual qualities and,
where possible, materials. Replacement of missing features shall be sustained by
documentary, physical, or pictorial evidence.
7. Chemical or physical treatments, such as sandblasting, that cause damage to
historic materials shall not be used. The surface cleaning of structures, if
appropriate, shall be undertaken using the gentlest means possible.
8. Significant archeological resources affected by a project shall be protected and
preserved. If such resources must be disturbed, mitigation measures shall be
undertaken.
9. New additions, exterior alterations, or related new construction shall not destroy
historic materials that characterize the property. The new work shall be
differentiated from the old and shall be compatible with the massing size, scale,
and architectural features to protect the historic integrity of the property and its
environment.
10. New additions and adjacent or related new construction shall be undertaken in
such a manner that if removed in the future, the essential form and integrity of the
historic property and its environment would be unimpaired.
The National Register
of Historic Places
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National Register Program
The National Register of Historic Places is the Nation's official list
of cultural resources worthy of preservation.
Administered by the National Park Service, the National Register
is part of a national program to coordinate and support public and
private efforts to identify, evaluate, and protect our historic and
archeological resources. National Historic Landmarks are the
most significant properties listed on the National Register.
Criteria for Evaluation of Significance
The quality of significance in American history, architecture,
archaeology, engineering, and culture is present in districts,
sites, buildings, structures, and objects that possess integrity
and:
A. that are associated with events that have made a
significant contribution to the broad patterns of our history; or
B. that are associated with the lives of persons significant in
our past; or
C. that embody the distinctive characteristics of a type,
period, or method of construction, represent the work of a
master, possess high artistic values, or represent a significant
and distinguishable entity whose components may lack
individual distinction; or
D. that have yielded or may be likely to yield, information
important in prehistory or history.
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Assessing Integrity
A property is evaluated for integrity of location,
design, setting, materials, workmanship, feeling, and
association.
Integrity is judged by whether the significant features
of the property are present, and whether the property
retains the identity for which it is significant.
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Chicago Park District, Special Collections
LW&Z Joint Venture
The Rehabilitation Tax Credit
Program
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Rehabilitation Tax Credit
Program
Current tax incentives for preservation,
established by the Tax Reform Act of 1986,
include:
ƒ 20% tax credit for the certified
rehabilitation of certified historic structures.
ƒ a 10% tax credit for the rehabilitation of
non-historic, non-residential buildings built
before 1936.
For both credits, the rehabilitation must be
a substantial one and must involve a
depreciable building. For historic
structures, the rehabilitation must follow
the Secretary of the Interior’s Standards.
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The Preservation Briefs
A wealth of knowledge can be found in the NPS Preservation
Briefs. Subjects include:
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Assessing Cleaning and Water-Repellent Treatments
for Historic Masonry Buildings
2
Repointing Mortar Joints in Historic Masonry Buildings
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Conserving Energy in Historic Buildings
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Roofing for Historic Buildings
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The Preservation of Historic Adobe Buildings
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Dangers of Abrasive Cleaning to Historic Buildings
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The Preservation of Historic Glazed Architectural Terra-Cotta
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Aluminum and Vinyl Siding on Historic Buildings: The
Appropriateness of Substitute Materials for Resurfacing
Historic Wood Frame Buildings
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The Repair of Historic Wooden Windows
10 Exterior Paint Problems on Historic Woodwork
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11 Rehabilitating Historic Storefronts
12 The Preservation of Historic Pigmented Structural Glass
(Vitrolite and Carrara Glass)
13 The Repair and Thermal Upgrading of Historic Steel
Windows
14 New Exterior Additions to Historic Buildings: Preservation
Concerns
15 Preservation of Historic Concrete: Problems and General
Approaches
16 The Use of Substitute Materials on Historic Building Exteriors
17 Architectural Character - Identifying the Visual Aspects of
Historic Buildings as an Aid to Preserving Their Character
18 Rehabilitating Interiors in Historic Buildings – Identifying
Character-Defining Elements
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19 The Repair and Replacement of Historic Wooden Shingle
Roofs
20 The Preservation of Historic Barns
21 Repairing Historic Flat Plaster - Walls and Ceilings
22 The Preservation and Repair of Historic Stucco
23 Preserving Historic Ornamental Plaster
24 Heating, Ventilating, and Cooling Historic Buildings:
Problems and Recommended Approaches
25 The Preservation of Historic Signs
26 The Preservation and Repair of Historic Log Buildings
27 The Maintenance and Repair of Architectural Cast Iron
28 Painting Historic Interiors
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29 The Repair, Replacement, and Maintenance of Historic Slate
Roofs
30 The Preservation and Repair of Historic Clay Tile Roofs
31 Mothballing Historic Buildings
32 Making Historic Properties Accessible
33 The Preservation and Repair of Historic Stained and Leaded
Glass
34 Applied Decoration for Historic Interiors: Preserving Historic
Composition Ornament
35 Understanding Old Buildings: The Process of Architectural
Investigation
36 Protecting Cultural Landscapes: Planning, Treatment and
Management of Historic Landscapes
37 Appropriate Methods of Reducing Lead-Paint Hazards in
Historic Housing
38 Removing Graffiti from Historic Masonry
39 Holding the Line: Controlling Unwanted Moisture in Historic
Buildings
40 Preserving Historic Ceramic Tile Floors
40 Preserving Historic Ceramic Tile Floors
41 The Seismic Retrofit of Historic Buildings: Keeping
Preservation in the Forefront
42 The Maintenance, Repair and Replacement of Historic Cast
Stone
43 The Preparation and Use of Historic Structure Reports
44 The Use of Awnings on Historic Buildings: Repair,
Replacement and New Design
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Concrete
Causes of deterioration:
ƒ Environmental factors
ƒ Materials and workmanship
ƒ Improper maintenance
Methods of Repair:
ƒ Cracks – fill or seal, depending
on size
ƒ Spalls – use formed patch of
matching concrete
ƒ Replacement – use proper mix
design and quality control
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Terra Cotta
Types of Deterioration:
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Crazing
Cracking
Spalling
Deterioration of metal anchorage
Deterioration of mortar in joints
Inappropriate past repairs
Maintenance, Repair, and
Replacement:
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Cleaning
Waterproofing
Crack repair – fills and sealants
Spall repair - patches
Anchorage repairs
Pointing
Temporary stabilization
Replacement
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Replacement materials:
ƒ Repair existing original terra cotta where possible.
ƒ If original cannot be repaired, replace with new
terra cotta.
ƒ If this is not possible, select the most appropriate
substitute material.
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Stucco
Guidelines for Repair:
ƒ Understand the original material
ƒ Design an appropriate repair mix,
matching the original stucco in
composition, color, and finish
texture
ƒ Remove deteriorated stucco
ƒ Prepare and clean areas to be
repaired
ƒ Key patches in place; use bonding
agents if appropriate
ƒ Install in layers
ƒ Moist cure
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Cleaning
Inappropriate cleaning can damage
historic masonry.
To ensure proper cleaning:
ƒ Understand the substrate
ƒ Identify prior treatments
ƒ Choose the correct cleaning
materials and methods:
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Water or steam
Chemical (including poultice)
Abrasive or microabrasive
Laser
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ƒ Consider appropriateness to substrate,
history of use, logistics, cost,
availability, and environmental and
safety factors.
ƒ Test cleaning systems prior to full-scale
use.
ƒ Evaluate success of cleaning effort in
terms of appearance, effect on
substrate, and practical considerations.
ƒ Prepare detailed construction
documents and provide quality control
during the work.
Undercleaning is likely to be aesthetically unacceptable,
whereas overcleaning is likely to be damaging to the substrate.
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Pointing
Mortar Mix Design:
ƒ Design the new mortar to match
the historic mortar in color,
texture, and tooling.
ƒ Provide new mortar with greater
vapor permeability and that is
softer than the masonry units.
Joint Preparation and Pointing:
ƒ Remove old mortar to proper
depth, taking care to avoid
damage to adjacent masonry.
ƒ Mix mortar carefully and install in
layers. Tool to match original
profile, and cure properly.
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Moisture Problems
Guidelines:
ƒ Avoid remedial treatments without
prior careful diagnosis.
ƒ In selecting treatments, protect the
historical significance of the
resource.
ƒ Address ground-related moisture
and rain run-off.
ƒ Manage existing moisture
conditions before introducing
humidification or dehumidification.
ƒ Implement a program of ongoing
monitoring and maintenance once
moisture is controlled or managed.
Key Questions to Ask:
ƒ How is moisture draining around
the building and site?
ƒ How does water/moisture appear
to be entering the building?
ƒ What are the principal moisture
dynamics?
ƒ How is the interior climate handling
moisture?
ƒ Is the moisture problem
intermittent, chronic, or related to
specific events (e.g., rainfall)?
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Water Repellent Treatments
Synopsis:
ƒ An overview of cleaning methods:
water, chemical, and abrasive
ƒ The difference between waterrepellent (breathable) coatings
and waterproof (surface-sealing)
coatings
ƒ When these types of
treatments are and are not
appropriate for historic masonry
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Other NPS Publications and Resources
Preservation Tech Notes
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Conference Proceedings
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Other NPS Publications
Parks Canada /
Parcs Canada
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Other Sources of Information
ƒ Association for Preservation Technology International (APT)
ƒ Historic Preservation Education Foundation (HPEF)
ƒ International Working Party for Documentation and Conservation of
Buildings, Sites, and Neighborhoods of the Modern Movement
(DOCOMOMO)
ƒ International Council on Monuments and Sites (ICOMOS)
ƒ US General Services Administration / Public Works Canada
ƒ National Trust for Historic Preservation, Heritage Canada
Foundation, and other nonprofit preservation advocacy organizations
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