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Historic Preservation - Technical Procedures

Spectitle:

Preservation Briefs: 32 Making Historic Properties Accessible

Procedure code:

0110011S

Source:

Preservation Briefs 32, National Park Service, Pad

Division:

General Requirements

Section:

Special Project Procedures

Last Modified:

09/05/2012

Details:

Preservation Briefs: 32 Making Historic Properties Accessible



PRESERVATION BRIEFS 32:  

MAKING HISTORIC PROPERTIES ACCESSIBLE

 

The link immediately below connects to the National Park Service Preservation Brief 32:

 

http://www.nps.gov/history/hps/tps/briefs/brief32.htm


Thomas C. Jester and Sharon C. Park, AIA

This standard includes the bulk of information contained in the
original Preservation Brief developed by the National Park Service.
To obtain a complete copy of this brief, including figures and
illustrations, please contact:  

              Superintendent of Documents
              P.O. Box 371954
              Pittsburgh, PA  15250-7954

              GPO #024-005-01121-8
              $1.50

Please call the Publication Order Information Desk at 202/783-3238
or FAX 202/512-2250 to verify price and availability.  


THE SECRETARY OF THE INTERIOR'S "STANDARDS FOR HISTORIC
PRESERVATION PROJECTS" EMBODY TWO IMPORTANT GOALS: 1) THE
PRESERVATION OF HISTORIC MATERIALS AND, 2) THE PRESERVATION OF A
BUILDING'S DISTINGUISHING CHARACTER.  EVERY OLD BUILDING IS UNIQUE,
WITH ITS OWN IDENTITY AND ITS OWN DISTINCTIVE CHARACTER.  CHARACTER
REFERS TO ALL THOSE VISUAL ASPECTS AND PHYSICAL FEATURES THAT
COMPRISE THE APPEARANCE OF EVERY HISTORIC BUILDING.

***INTRODUCTION***

Historically, most buildings and landscapes were not designed to be
readily accessible for people with disabilities.  In recent years,
however, emphasis has been placed on preserving historically
significant properties, and on making these properties--and the
activities within them--more accessible to people with
disabilities. With the passage of the Americans with Disabilities
Act in 1990, access to properties open to the public is now a civil
right.

This Preservation Brief introduces the complex issue of providing
accessibility at historic properties, and underscores the need to
balance accessibility and historic preservation. It provides
guidance on making historic properties accessible while preserving
their historic character; the Brief also provides examples to show
that independent physical accessibility at historic properties can
be achieved with careful planning, consultation, and sensitive
design. While the Brief focuses primarily on making buildings and
their sites accessible, it also includes a section on historic
landscapes. The Brief will assist historic property owners, design
professionals, and administrators in evaluating their historic
properties so that the highest level of accessibility can be
provided while minimizing changes to historic materials and
features. Because many projects encompassing accessibility work are
complex, it is advisable to consult with experts in the fields of
historic preservation and accessibility before proceeding with
permanent physical changes to historic properties.

Modifications to historic properties to increase accessibility may
Be as simple as a small, inexpensive ramp to overcome one entrance
step, or may involve challenges to exterior and interior features.
The Brief does not provide a detailed explanation of local or State
accessibility laws as they vary from jurisdiction to jurisdiction.
A concise explanation of several federal accessibility laws is
included at the end of this brief.


***PLANNING ACCESSIBILITY MODIFICATIONS***

Historic properties are distinguished by features, materials,
spaces, and spatial relationships that contribute to their historic
character. Often these elements, such as steep terrain, monumental
steps, narrow or heavy doors, decorative ornamental hardware, and
narrow pathways and corridors, pose barriers to persons with
disabilities, particularly to wheelchair users.  A three-step
approach is recommended to identify and implement accessibility
modifications that will protect the integrity and historic
character of historic properties:

    1.   Review the historical significance of the property and
         identify character-defining features;

    2.   Assess the property's existing and required level of,
         accessibility; and

    3.   Evaluate accessibility options within a preservation
         context.


1.   REVIEW THE HISTORICAL SIGNIFICANCE OF THE PROPERTY:

If the property has been designated as historic (properties that
are listed in, or eligible for listing in the National Register of
Historic Places, or designated under State or local law), the
property's nomination file should be reviewed to earn about its
significance. Local preservation commissions and State Historic
Preservation Offices can usually provide copies of the nomination
file and are also resources for  additional information and
assistance. Review of the written documentation should always be
supplemented with a physical investigation to identify which
character-defining features and spaces must be protected whenever
any changes are anticipated. If the level of documentation for a
property's significance is limited, it may be necessary to have a
preservation professional identify specific historic features,
materials, and spaces that should be protected.

For most historic properties, the construction materials, the form
and style of the property, the principal elevations, the major
architectural or landscape features, and the principal public
spaces constitute some of the elements that should be preserved.
Every effort should be made to minimize damage to the materials and
features that convey a property's historical significance when
making modifications for accessibility. Very small or highly
significant properties that have never been altered may be
extremely difficult to modify.

Secondary spaces and finishes and features that may be less
important to the historic character should also be identified;
these may generally be altered without jeopardizing the historical
significance of a property. Non-significant spaces, secondary
pathways, later additions, previously altered areas, utilitarian
spaces, and service areas can usually be modified without
threatening or destroying a property's historical significance.

2.   ASSESS THE PROPERTY'S EXISTING AND REQUIRED LEVEL OF
    ACCESSIBILITY:

A building survey or assessment will provide a thorough evaluation
of a property's accessibility. Most surveys identify accessibility
barriers in the following areas: building and site entrances;
surface textures, widths and slopes of walkways; parking; grade
changes; size, weight and configuration of doorways; interior
corridors and path of travel restrictions; elevators; and public
toilets and amenities. Simple audits can be completed by property
owners using readily available checklists.  Accessibility
specialists can be hired to assess barriers in more complex
properties, especially those with multiple buildings, steep
terrain, or interpretive programs. Persons with disabilities can be
particularly helpful in assessing specific barriers.  All
applicable accessibility requirements--local cades, State codes and
federal laws--should be reviewed carefully before undertaking any
accessibility modification. Since many States and localities have
their own accessibility regulations and codes (each with their own
requirements for dimensions and technical requirements), owners
should use the most stringent accessibility requirements when
implementing modifications. The Americans with Disability Act
Accessibility Guidelines (ADAAG) is the document that should be
consulted when complying with the Americans with Disabilities Act
(ADA) requirements.

3.   IDENTIFY AND EVALUATE ACCESSIBILITY OPTIONS WITHIN A
    PRESERVATION CONTEXT:

Once a property's significant materials and features have been
identified, and existing and required levels of accessibility have
been established, solutions can be developed. Solutions should
provide the greatest amount of accessibility without threatening or
destroying those materials and features that make a property
significant. Modifications may usually be phased over time as funds
are available, and interim solutions can be considered until more
permanent solutions are implemented. A team comprised of persons
with disabilities, accessibility and historic preservation
professionals, and building inspectors should be consulted as
accessibility solutions are developed.

Modifications to improve accessibility should generally be based on
the following priorities:

    1.   Making the main or a prominent public entrance and
         primary public spaces accessible, including a path to the
         entrance;

    2.   Providing access to goods, services, and programs;

    3.   Providing accessible restroom facilities; and,

    4.   Creating access to amenities and secondary spaces.

All proposed changes should be evaluated for conformance with the
Secretary of the Interior's "Standards for the Treatment of
Historic Properties," which were created for property owners to
guide preservation work. These Standards stress the importance of
retaining and protecting the materials and features that convey a
property's historical significance. Thus, when new features are
incorporated for accessibility, historic materials and features
should be retained whenever possible.  Accessibility modifications
should be in scale with the historic property, visually compatible,
and, whenever possible, reversible. Reversible means that if the
new feature were removed at a later date, the essential form and
integrity of the property would be unimpaired. The design
of new features should also be differentiated from the
design of the historic property so that the evolution of the
property is evident.

In general, when historic properties are altered, they should
be made as accessible as possible. However, if an owner or
a project team believes that certain modifications would
threaten or destroy the significance of the property, the
State Historic Preservation Officer should be consulted to
determine whether or not any special accessibility
provisions may be used. Special accessibility provisions for
historic properties will vary depending on the applicable
accessibility requirements.

In some cases, programmatic access may be the only option
for extremely small or unaltered historic properties, such as
a two-story house museum with no internal elevator.
Programmatic access for historic properties refers to
experiences when physical access cannot be provided. It
may mean offering an audio-visual program showing an
inaccessible upper floor of an historic house museum,
providing interpretive panels from a vista at an inaccessible
terraced garden, or creating a tactile model of a historic
monument for people with visual impairments.


***ACCESSIBILITY SOLUTIONS***

The goal in selecting appropriate solutions for specific
historic properties is to provide a high level of accessibility
without compromising significant features or the overall
character of the property. The following sections describe
accessibility solutions and offer guidance on specific
historic property components, namely the building site,
entrances, interiors, landscapes, amenities, and new
additions. Several solutions are discussed in each section,
referencing dimensions and technical requirements from the ADA's
accessibility guidelines, ADAAG. State and local requirements,
however, may differ from the ADA requirements. Before making any
modification owners should be aware of all applicable accessibility
requirements.

THE BUILDING SITE:

An accessible route from a parking lot, sidewalk, and public street
to the entrance of an historic building or facility is essential.
An accessible route, to the maximum extent possible, should be the
circulation route used by the general public. Critical elements of
accessible routes are their widths, slopes, cross slopes, and
surface texture. Each of these route elements must be appropriately
designed so that the route can be used by everyone, including
people with disabilities. The distance between the arrival and
destination points should also be as short as possible. Sites
containing designed landscapes should be carefully evaluated before
making accessibility modifications.  Historic landscapes are
described in greater detail on later pages.

Providing Convenient Parking:

If parking is provided, it should be as convenient as possible for
people with disabilities. Specially designated parking can often be
created to improve accessibility. Modifications to parking
configurations and pathways should not alter significant landscape
features.

Creating an Accessible Route:

The route or path through a site to a historic building's entrance
should be wide enough, generally at least 3 feet (91 cm), to
accommodate visitors with disabilities and must be appropriately
graded with a stable, firm, and slip-resistant surface. Existing
paths should be modified to meet these requirements whenever
possible as long as doing so would not threaten or destroy
significant materials and features.

Existing surfaces can often be stabilized by providing a new base
and resetting the paving materials, or by modifying the path
surface. In some situations it may be appropriate to create a new
path through an inaccessible area. At large properties, it may be
possible to regrade a slope to less than 1:20 (5%), or to introduce
one or more carefully planned ramps. Clear directional signs should
mark the path from arrival to destination.

ENTRANCES:

Whenever possible, access to historic buildings should be through
a primary public entrance. In historic buildings, if this cannot be
achieved without permanent damage to character-defining features,
at least one entrance used by the public should be made accessible.
If the accessible entrance is not the primary public entrance,
directional signs should direct visitors to the  accessible
entrance.  A rear or service entrance should be avoided as the only
means of entering a building. Creating an accessible entrance
usually involves overcoming a change in elevation. Steps, landings,
doors, and thresholds, all part of the entrance, often pose
barriers for persons with disabilities. To preserve the integrity
of these features, a number of solutions are available to increase
accessibility. Typical solutions include regrading, incorporating
ramps, installing wheelchair lifts, creating new entrances, and
modifying doors, hardware, and thresholds.

Regrading an Entrance:

In some cases, when the entrance steps and landscape features are
not highly significant, it may be possible to regrade to provide a
smooth entrance into a building. If the existing steps are historic
masonry, they should be buried, whenever possible, and not removed.

Incorporating Ramps:

Permanent ramps are perhaps the most common means to make an
entrance accessible. As a new feature, ramps should be carefully
designed and appropriately located to preserve a property's
historic character.  Ramps should be located at public entrances
used by everyone whenever possible, preferably where there is
minimal change in grade. Ramps should also be located to minimize
the loss of historic features at the connection points--porch
railings, steps, and windows--and should preserve the overall
historic  setting and character of the property. Larger buildings
may have below grade areas that can accommodate a ramp down to an
entrance. Below grade entrances can be considered if the ramp leads
to a publicly used interior, such as an auditorium, or if the
building is serviced by a public elevator.  Ramps can often be
incorporated behind historic features, such as cheek-walls or
railings, to minimize the visual effect.

The steepest allowable slope for a ramp is usually 1:12 (8%), but
gentler slopes should be used whenever possible to accommodate
people with limited strength. Greater changes in elevation require
larger and longer ramps to meet accessibility scoping provisions
and may require an intermediate landing. Most codes allow a
slightly steeper ramp for historic buildings to overcome one step.

Ramps can be faced with a variety of materials, including wood,
brick, and stone. Often the type and quality of the materials
determines how compatible a ramp design will be with a historic
property. Unpainted pressure-treated wood should not be used to
construct ramps because it usually appears temporary and is not
visually compatible with most historic properties. Railings should
be simple in design, distinguishable from other historic features,
and  should extend one foot beyond the sloped area.

Ramp landings must be large enough for wheelchair users, usually at
least 5 feet by 5 feet (152.5 cm by 152.5 cm), and the top landing
must be at the level of the door threshold. It may be possible to
reset steps by creating a ramp to accommodate minor level changes
and to meet the threshold without significantly altering a
property's historic character. If a building's existing landing is
not wide or deep enough to accommodate a ramp, it may be necessary
to modify the entry to create a wider landing.  Long ramps, such as
switchbacks, require intermediate landings, and all ramps should be
detailed with an appropriate edge and railing for wheelchair users
and visually impaired individuals.

Temporary or portable ramps are usually constructed of light-weight
materials and, thus, are rarely safe or visually compatible with
historic properties. Moreover, portable ramps are often stored
until needed and, therefore, do not meet accessibility requirements
for independent access.  Temporary and portable ramps, however, may
be an acceptable interim solution to improve accessibility until a
permanent solution can be implemented.

Installing Wheelchair Lifts:

Platforms lifts and inclined stair lifts, both of which accommodate
only one person, can be used to overcome changes of elevation
ranging from three to ten feet (.9 m -3 m) in height. However, many
States have restrictions on the use of wheelchair lifts, so all
applicable codes should be reviewed carefully before installing
one.  Inclined stair lifts, which carry  a wheelchair on a platform
up a flight of stairs, may be employed selectively.  They tend to
be visually intrusive, although they are relatively reversible.
Platform lifts can be used when there is inadequate space for a
ramp.  However, such lifts should be installed in unobtrusive
locations and under cover to minimize maintenance if at all
possible. A similar, but more expensive platform lift has a
retracting railing that lowers into the ground, minimizing the
visual effect to historic properties. Mechanical lifts have
drawbacks at historic properties with high public visitation
because their capacity is limited, they sometimes cannot be
operated independently, and they require frequent maintenance.

Considering a New Entrance:

When it is not possible to modify an existing entrance, it may be
possible to develop new entrance by creating an entirely new
opening in an appropriate location, or by using a secondary window
for an opening. This solution should only be considered after
exhausting all possibilities for modifying existing entrances.

Retrofitting Doors:

Historic doors generally should not be replaced, nor should door
frames on the primary elevation be widened, as this may alter an
important  feature of a historic design. However, if a building's
historic doors have been removed, there may be greater latitude in
designing a compatible new entrance. Most accessibility standards
require at least a 32" (82 cm) clear opening with manageable door
opening pressures. The most desirable preservation solution to
improve accessibility is retaining historic doors and upgrading the
door pressure with one of several devices. Automatic door openers
(operated by push buttons, mats, or electronic eyes) and
power-assisted door openers can eliminate or reduce door pressures
that are accessibility barriers, and make single or double-leaf
doors fully operational.

Adapting Door Hardware:

If a door opening is within an inch or two of meeting the 32" (81
cm) clear opening requirement, it may be possible to replace the
standard hinges with off-set hinges to increase the size of the
door opening as much as 1-1/2" (3.8 cm). Historic hardware can be
retained in place, or adapted with the addition of an automatic
opener, of which there are several types. Door hardware can also be
retrofitted to reduce door pressures.  For example, friction hinges
can be retrofitted with ballbearing inserts, and door closers can
be rethreaded to reduce the door pressure.

Altering Door Thresholds:

A door threshold that exceeds the allowable height, generally l/2"
(1.3 cm), can be altered or removed with one that meets applicable
accessibility requirements. If the threshold is deemed to be
significant, a bevel can be added on each side to reduce its
height.  Another solution is to replace the threshold with one that
meets applicable accessibility requirements and is visually
compatible with the historic entrance.

MOVING THROUGH HISTORIC INTERIORS:

Persons with disabilities should have independent access to all
public areas and facilities inside historic buildings. The extent
to which a historic interior can be modified depends on the
significance of its materials, plan, spaces, features, and
finishes. Primary spaces are often more difficult to modify without
changing their character. Secondary spaces may generally be changed
without compromising a building's historic character. Signs should
clearly mark the route to accessible restrooms, telephones, and
other accessible areas.  

Installing Ramps and Wheelchair Lifts:

If space permits, ramps and wheelchair lifts can also be used to
increase  accessibility inside buildings.  However, some States and
localities restrict interior uses of wheelchair lifts for
life-safety reasons. Care should be taken to install these new
features where they can be readily accessed. Ramps and wheelchair
lifts are described earlier in this brief.  

Upgrading Elevators:

Elevators are an efficient means of providing accessibility between
floors. Some buildings have existing historic elevators that are
not adequately accessible for persons with disabilities because  of
their size, location, or detailing, but they may also contribute to
the historical significance of a building. Significant historic
elevators can usually be upgraded to improve accessibility. Control
panels can be modified with a "wand" on a cord to make the control
panel accessible, and timing devices can usually he adjusted.

Retrofitting Door Knobs:

Historic door knobs and other hardware may be difficult to grip and
turn. In recent years, lever-handles have been developed to replace
door knobs.  Other lever-handle devices can be added to existing
hardware. If it is not possible or appropriate to retrofit existing
door knobs, doors can be left open during operating hours (unless
doing so would violate life safety codes), and power-assisted door
openers can be installed. It may only be necessary to retrofit
specific doorknobs to create an accessible path of travel and
accessible restrooms.

Modifying Interior Stairs:

Stairs are the primary barriers for many people with disabilities.
However, there are some ways to modify stairs to assist people who
are able to navigate them. It may be appropriate to add hand
railings if none exist. Railings should be 1-1/4" (3.8 cm) in
diameter and return to the wall so straps and bags do not catch.
Color-contrasting, slip-resistant strips will help people with
visual impairments. Finally, beveled or closed risers are
recommended unless the stairs are highly significant, because open
risers catch feet.  

BUILDING AMENITIES:

Some amenities in historic buildings, such as restrooms, seating,
telephones, drinking fountains, counters, may contribute to a
building's historic character. They will often require modification
to improve their use by persons with disabilities. In many cases,
supplementing existing amenities, rather than changing or removing
them, will increase access and minimize changes to historic
features and materials.

Upgrading  Restrooms:

Restrooms may have historic fixtures such as sinks, urinals, or
marble partitions that can be retained in the process of making
modifications. For example, larger restrooms can sometimes be
reconfigured by relocating or combining partitions to create an
accessible toilet stall. Other changes to consider are adding grab
bars around toilets, covering hot water pipes under sinks with
insulation to prevent burns, and providing a sink, mirror, and
paper dispenser at a height suitable for wheelchair users. A unisex
restroom may be created if it is technically infeasible to create
two fully accessible restrooms, or if doing so would threaten or
destroy the significance of the building. It is important to
remember that restroom fixtures, such as sinks, urinals, and
partitions, may be historic, and therefore, should be preserved
whenever possible.

Modifying Other Amenities:

Other amenities inside historic buildings may require modification.
Seating in a theater, for example, can be made accessible by
removing some seats in several areas. New seating that is
accessible can also be added at the end of existing rows, either
with or without a level floor surface.  Readily removable seats may
be installed in Wheelchair Spaces when the spaces are not required
to accommodate wheelchair users.  Historic water fountains can be
retained and new, two-tiered fountains installed if space permits.
If public telephones are provided, it may be necessary to install
at least a Text Telephone (TT), also known as a Telecommunication
Device for the Deaf (TDD). Historic service counters commonly found
in banks, theaters, and hotels generally should not be altered.  It
is preferable to add an accessible counter on the end of a historic
counter if feasible.  Modified or new counters should not exceed
36" (91.5 cm) in height.

CONSIDERING A NEW ADDITION AS AN ACCESSIBILITY SOLUTION:

Many new additions are constructed specifically to incorporate
modern amenities such as elevators, restrooms, fire stairs, and new
mechanical equipment. These new additions often create
opportunities to incorporate access for people with disabilities.
It may be possible, for example, to create an accessible entrance,
path to public levels via a ramp, lift, or elevator. However, a new
addition has the potential to change a historic property's
appearance and destroy significant building and landscape features.
Thus, all new additions should be compatible with the size, scale,
and proportions of historic features and materials that
characterize a property.

New additions should be carefully located to minimize connection
points with the historic building, such that if the addition were
to be removed in the future, the essential form and integrity of
the building would remain intact. On the other hand, new additions
should also be conveniently located near parking that is connected
to an accessible route for people with disabilities. As new
additions are incorporated, care should be taken to protect
significant landscape features and archeological resources.
Finally, the design for any new addition should be differentiated
from the historic design so that the property's evolution over time
is clear. New additions frequently make it possible to increase
accessibility, while simultaneously reducing the level of change to
historic features, materials, and spaces.


***CONCLUSION***

Historic properties are irreplaceable and require special care to
ensure their preservation for future generations. With the passage
of the Americans with Disabilities Act, access to historic
properties open to the public is now a civil right, and owners of
historic properties must evaluate existing buildings and determine
how they can be made more accessible. It is a challenge to evaluate
properties thoroughly, to identify the applicable accessibility
requirements, to explore alternatives and to implement solutions
that provide independent access and are consistent with accepted
historic preservation standards. Solutions for accessibility should
not destroy a property's significant materials, features and
spaces, but should increase accessibility as much as possible. Most
historic buildings are not exempt from providing accessibility, and
with careful planning, historic properties can be made more
accessible, so that all citizens can enjoy our Nation's diverse
heritage.


***READILY ACHIEVABLE ACCESSIBILITY MODIFICATIONS***

Many accessibility solutions can be implemented easily and
inexpensively without destroying the significance of historic
properties. While it may not be possible to undertake all of the
modifications listed below, each change will improve accessibility.

Sites and Entrances:

-    Creating a designated parking space.

-    Installing ramps.

-    Making curb cuts.

Interiors:

-    Repositioning shelves.

-    Rearranging tables, displays, and furniture.

-    Repositioning telephones.

-    Adding raised markings on elevator control buttons.

-    Installing flashing alarm lights.

-    Installing offset hinges to widen doorways.

-    Installing or adding accessible door hardware.

-    Adding an accessible water fountain, or providing a paper cup
    dispenser at an inaccessible water fountain.

Restrooms:

-    Installing grab bars in toilet stalls.

-    Rearranging toilet partitions to increase maneuvering space.

-    Insulating lavatory pipes under sinks to prevent burns

-    Installing a higher toilet seat.

-    Installing a full-length bathroom mirror.

    -    Repositioning the paper towel dispenser.


***MAKING HISTORIC LANDSCAPES ACCESSIBLE***

To successfully incorporate access into historic landscapes, the
planning process is similar to that of other historic properties.
Careful research and inventory should be undertaken to determine
which materials and features convey the landscape's historical
significance.  As part of this evaluation, those features that are
character-defining (topographical variation, vegetation,
circulation, structures, furnishings, objects) should be
identified.  Historic finishes, details, and materials that also
contribute to a landscape's significance should also be documented
and evaluated prior to determining an approach to landscape
accessibility.  For example, aspects of the pedestrian circulation
system that need to be understood include walk width, aggregate
size, pavement pattern, texture, relief, and joint details.  The
context of the walk should be understood including its edges and
surrounding area.  Modifications to surface textures or widths of
pathways can often be made with minimal effect on significant
landscape features.

Additionally, areas of secondary importance such as altered paths
should be identified -- especially those where the accessibility
modifications will not destroy a landscape's significance.  By
identifying those features that are contributing or non-contributing, a sympathetic circulation
experience can then be
developed.

After assessing a landscape's integrity, accessibility solutions
can be considered.  Full access throughout a historic landscape
many not always be possible.  Generally, it is easier to provide
accessibility to larger, more open sites where there is a greater
variety of public experiences.  However, when a landscape is
uniformly steep, it may only be possible to make discrete portions
meaning of the landscape?




    courtyard as well.
 


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