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The Chevy Chase Presbyterian Church
had suffered the effects of time and
was in need of proper preservation
and restoration.
The Property Restoration
Committee was vigilant enough to investigate
these problems and seek appropriate
restoration as opposed to quick fixes that
simply put off the inevitable.
Inevitably, the process of history had brought
with it a marked deterioration of the stately
Church’s stone structure. For over three
quarters of a century, the elegant stone walls
and bell tower had suffered
the injuries of time;
many of these injuries
were hidden, making access
extremely difficult
which in turn had prevented
proper restoration.
Mortar joints were
cracked open; irreplaceable
stones were spalling
or exfoliating; roof flashing
and gutter joints were
failing and allowing water
into the walls; roof
fabric was deteriorated;
coping stones were self-destructing.
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| Exfoliating stone. |
With proper preservation and
restoration procedures and proven materials,
the deterioration and destruction was arrested
and corrected so this natural course
of self destruction would not accelerate or
lead to a permanent loss of historic fabric
and more costly repairs later. In this situation, water infiltration was the
main problem. Why was the water infiltration
so destructive? Open mortar joints, even
hairline cracks, allowed water to infiltrate
into the stone and walls where it expand and
contract and loosened the stones. Once the
setting mortar deteriorated between the
stones and cracks, only the force of gravity
held them in place. On vertical walls, open
joints caused the stone to exfoliate.
There
was the usual efflorescence or white powder
that collected where the moisture evaporated
out of the stone and the salt came to
the surface. This problem, once started, was
very difficult to stop unless the moisture infiltration
into the stone was completely
stopped. The wrong mortar mix or sealant
could cause even more damage; if it was too
hard it would spall the stone around the joint,
if it was too soft it would fall out; if too much
Portland cement was added, it would not
expand and contract. The wrong joint sealant,
for example, between stones, under gutters or where a new roof had been installed
could eventually destroy soft limestone or
pull loose and allow water to infiltrate into
the stone or walls. Improperly installed
flashing and gutters could exacerbate the
problem even more.
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| White
powdery residue is noticeable where salts have migrated to the
surface |
Preservation Trades Company's’ restoration of Chevy Chase Presbyterian
was completed using a carefully
devised timeline. This allowed the craftsmen
to work under various weather conditions
and constraints. Parapet stones were
replaced and lead coated copper throughwall
flashing was installed. Copper scuppers
and downspouts were replaced with new. In
addition to replacing the roofs, the entire
building was repointed with a historic pointing
mortar that carefully matched the original.
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