Moravian Preservation Master Plan.indb - Society for College and ...
Moravian Preservation Master Plan.indb - Society for College and ...
Moravian Preservation Master Plan.indb - Society for College and ...
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<strong>Moravian</strong> <strong>College</strong> • <strong>Preservation</strong> <strong>Master</strong> <strong>Plan</strong><br />
typically infiltrate windows at the perimeter of the<br />
window sash <strong>and</strong> at lower window rails. Water<br />
problems are exacerbated in areas which do not<br />
shed water, such as improperly sloped window<br />
sills, at rough surfaces, or in pockets created by<br />
missing glazing putty. Window sills are often the<br />
first elements to exhibit deterioration. Condensation<br />
that <strong>for</strong>ms on interior window surfaces can also<br />
cause deterioration. It is important to distinguish<br />
moisture penetration caused by condensation from<br />
that caused by water infiltration. Each requires<br />
different remediation techniques.<br />
Windows that have been protected from the<br />
elements by exterior storm sash are not immune<br />
from moisture-related problems. Poorly ventilated<br />
storm windows can actually accelerate damage to<br />
wood <strong>and</strong> metal windows. Condensation <strong>for</strong>ms as<br />
the warm interior air meets the cool exterior storm<br />
window. If there is no ventilation, condensation is<br />
trapped against the sash, causing failure of finishes<br />
<strong>and</strong>, ultimately, wood rot or corrosion.<br />
Window operation is impaired by loose joints <strong>and</strong><br />
misaligned sash. Maintenance level painting often<br />
covers hinges <strong>and</strong> other moving parts, eventually<br />
causing excessive paint build-up. This can lead to<br />
sticking or inoperable sash.<br />
Window Repair<br />
Historic windows should never be replaced unless<br />
they are missing or beyond repair. Contrary to<br />
popular belief, repaired historic windows will<br />
last far longer than most modern replacement<br />
windows because they are made with superior<br />
quality materials <strong>and</strong> craftsmanship, especially<br />
wood windows. Epoxy consolidants may be used<br />
to strengthen <strong>and</strong> save deteriorated wood elements,<br />
especially at sills. Special patching compounds<br />
may be used to repair steel window parts. Warped<br />
wood sash <strong>and</strong> bowed or bent steel sash can often<br />
be repaired by skilled craftsmen.<br />
Replacing deteriorated parts, not the entire window,<br />
is the preferred solution, using elements that are<br />
visually <strong>and</strong> physically compatible with original.<br />
Historic windows are easily disassembled <strong>for</strong><br />
cleaning <strong>and</strong> repair. Unlike modern replacement<br />
windows, historic window units were constructed<br />
so that damaged portions could be repaired or<br />
replaced one part at a time. Individual window<br />
elements that should be retained include frames,<br />
sash, muntins, glazing, sills, lintels, hardware,<br />
heads, hoods, paneled or decorative jambs <strong>and</strong><br />
moldings, interior <strong>and</strong> exterior shutters, <strong>and</strong> blinds.<br />
The damaged portion of a window component<br />
should be replaced with material matching the<br />
original material <strong>and</strong> fabrication techniques.<br />
Any repair should match historic window sash,<br />
muntin configuration, reveal depths, glass-toframe<br />
ratios, glazing patterns, frame dimensions,<br />
trim profiles, <strong>and</strong> decorative features. Replacement<br />
glazing should match the qualities of the historic;<br />
low-E <strong>and</strong> reflective glazing are not appropriate in<br />
historic contexts. New window elements should<br />
be based on surviving prototypes including hood<br />
molds, sash, sills <strong>and</strong> interior or exterior shutters.<br />
Windows should also operate smoothly. Window<br />
mechanisms such as sash locks, cords, <strong>and</strong> weights<br />
should be maintained, repaired <strong>and</strong>, if necessary,<br />
replaced. This approach results in cost savings,<br />
because when properly maintained, historic<br />
windows can last <strong>for</strong> decades.<br />
Removal of prominent window features should<br />
be avoided because it damages a building’s<br />
architectural integrity. Important features include<br />
frames, sash, muntins, glazing <strong>and</strong> glazing patterns,<br />
sills, hardware, heads, hoods, paneled or decorative<br />
jambs <strong>and</strong> moldings, interior <strong>and</strong> exterior shutters,<br />
<strong>and</strong> blinds. They should not be blocked, infilled, or<br />
obscured.<br />
Window Weatherization<br />
Historic repairable windows should never be<br />
replaced with new units simply as a weatherization<br />
measure. Most loss of thermal efficiency at a<br />
window occurs around a leaky frame rather than<br />
through the sash itself. This can be addressed<br />
through simple weatherization techniques such<br />
as installing weather-stripping or storm windows.<br />
Weatherization techniques can greatly increase<br />
the energy efficiency of the overall building<br />
envelope <strong>and</strong> are always less costly than wholesale<br />
replacement of an entire window unit.<br />
Weatherization<br />
Historic windows can be made as energy efficient as<br />
new windows through the installation of weatherstripping.<br />
Weatherstripping methods include<br />
installation of compressed metal or spring clips<br />
or compressed foam tape. Weather-stripping is<br />
installed between the window frame <strong>and</strong> operable<br />
sash <strong>and</strong> along the meeting rails of the sash. Do<br />
not apply reflective or insulating film to window<br />
John Milner Associates • October 2009 • Chapter 9 • Building Guidelines • 306