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 standards could lead to safe, workable alternatives that preserve
the building. For instance, one or more new fireproof stair
towers might be added in less visible locations.
Automatic fire detection and suppression systems can lower
the risk caused by inadequate exit provisions or obsolete
construction materials. However, the system should be carefully
selected and installed in a way that will have as little impact
as possible on the historic fabric of the structure.
"Archaic" building materials are those which are considered
to have been out of general use for at least 30 years. They are
not necessarily unsafe. Usually they have gone out of use for
economic or technical reasons. Consulting older city or state
construction codes or Rehabilitation Guidelines 1980: 8.
Guidelines on Fire Ratings of Archaic Materials and Assemblies
(U.S. Department of Housing and Urban Development, Office of
Policy Development and Research; prepared by the National
Institute of Building Sciences) can be helpful in assessing the
safety performance of archaic materials and assemblies.
3.4.2 Health Hazards. Old buildings that appear to be in
good condition may actually be hiding a variety of threats to the
health of occupants and maintenance personnel. Becoming aware of
these potential hazards is an important part of any safe and
effective historic preservation maintenance program. The use of
some building materials commonly found in older buildings, such
as asbestos, is no longer allowed because the materials have been
found to be dangerous to humans. Some restoration techniques use
chemical or abrasive cleaners that have to be handled carefully
in order not to create hazardous conditions. Old chimneys and
flues that are blocked or left uncleaned may prevent ventilation
from the heating system. Some old buildings are sealed so
tightly with heavy insulation, weatherstripping, and vapor
barriers that the indoor air quality is harmed by inadequate
ventilation.
With sensible precautions, renovation and preservation
maintenance procedures can be performed safely. Be alert to
possible hazards; provide adequate ventilation, either natural or
mechanical; and wear protective masks or clothing, as needed.
Before beginning any maintenance project, identify and
analyze the potential level of risk from hazardous conditions
within the structure. Samples of any doubtful materials found
should be taken to a qualified laboratory for analysis.
Some of the more typical hazardous materials and their
handling are discussed below:
o Asbestos. Asbestos is a naturally occurring mineral that
once was considered almost the ideal building material,
but is now known to be dangerous to human health. Between
1890 and the early 1970s, it was commonly used as
insulation in houses and in as many as 3,000 other
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