True divided lights are desirable, but accurately matching
the size and profile of the historic muntins is just as important.
Beaded and ogee-shaped glazing beads are a poor match for
the simple putty bevel of a historic window. Exterior applied
muntins--when backed up by between-the-glass spacers and/or
interior muntins--may adequately convey the effect of divided lights on high upper floors. On lower floors, the historic windows should be retained and preserved.
A new sample muntin (above), with its shallow, irregular profile,
looks very different from the simple, deeper profile of the
glazing putty on the historic window. The new muntin would
not be an acceptable replacement. Photo:
Successful replacement windows depend not only on the match
of the windows themselves, but also on the way they are installed
in the wall. The relationship of window to wall plane should
not change when a window is replaced. Installing a full replacement
unit without removing the existing jambs will usually reduce
the glass size and unacceptably compromise the match.
The way a historic window operates is a major component of its
appearance. While a replacement window should capture the visual
effect of that operation, it does not have to operate in the
same way or at all.
Right: The heavier frame of the pivot sash in this historic industrial
building creates a distinctive pattern in the overall grid
of muntins. This visual distinction can clearly be reproduced
in any replacement window, regardless of how or whether the
Photo: NPS files