It may be necessary to carry out an immediate and temporary stabilization
to prevent further deterioration until research can determine
how the roof should be restored or rehabilitated, or until funding
can be provided to do a proper job. A simple covering of exterior
plywood or roll roofing might provide adequate protection, but
any temporary covering should be applied with caution. One should
be careful not to overload the roof structure, or to damage or
destroy historic evidence or fabric that might be incorporated
into a new roof at a later date. In this sense, repairs with caulking
or bituminous patching compounds should be recognized as potentially
harmful, since they are difficult to remove, and at their best,
are very temporary.
The architect or contractor should warn the owner of any precautions
to be taken against the specific hazards in installing the roofing
material. Soldering of sheet metals, for instance, can be a fire
hazard, either from the open flame or from overheating and undetected
smoldering of the wooden substrate materials.
Thought should be given to the design and placement of any modern
roof appurtenances such as plumbing stacks, air vents, or TV antennas.
Consideration should begin with the placement of modern plumbing
on the interior of the building, otherwise a series of vent stacks
may pierce the roof membrane at various spots creating maintenance
problems as well as aesthetic ones. Air handling units placed
in the attic space will require vents which, in turn, require
sensitive design. Incorporating these in unused chimneys has been
very successful in the past.
Whenever gutters and downspouts are needed that were not on the
building historically, the additions should be made as unobtrusively
as possible, perhaps by painting them out with a color compatible
with the nearby wall or trim.
 Special problems inherent in the design of an elaborate historic roof can be controlled through regular maintenance. The shape and detailing are essential elements of the building's historic character, and should not be modified, despite the use of alternative surface materials. Photo: NPS files. |
Although a new roof can be an object of beauty, it will not be
protective for long without proper maintenance. At least twice
a year, the roof should be inspected against a checklist. All
changes should be recorded and reported. Guidelines should be
established for any foot traffic that may be required for the
maintenance of the roof. Many roofing materials should not be
walked on at all. For some--slate, asbestos, and clay tile--a
self-supporting ladder might be hung over the ridge of the roof,
or planks might be spanned across the roof surface. Such items
should be specifically designed and kept in a storage space accessible
to the roof. If exterior work ever requires hanging scaffolding,
use caution to insure that the anchors do not penetrate, break,
or wear the roofing surface, gutters, or flashing.
Any roofing system should be recognized as a membrane that is
designed to be self-sustaining, but that can be easily damaged
by intrusions such as pedestrian traffic or fallen tree branches.
Certain items should be checked at specific times. For example,
gutters tend to accumulate leaves and debris during the spring
and fall and after heavy rain. Hidden gutter screening both at
downspouts and over the full length of the gutter could help keep
them clean. The surface material would require checking after
a storm as well. Periodic checking of the underside of the roof
from the attic after a storm or winter freezing may give early
warning of any leaks. Generally, damage from water or ice is less
likely on a roof that has good flashing on the outside and is
well ventilated and insulated on the inside. Specific instructions
for the maintenance of the different roof materials should be
available from the architect or contractor.
"Roofing" an Historic Preservation Brief
