Figure 4-23.-Typical double-hung window.
provide protection before and after they are placed in
location. Compression weather stripping, for example,
Insulated glass, used both for stationary and move-
able sash, consists of two or more sheets of spaced glass
with hermetically sealed edges. It resists heat loss more
than a single thickness of glass and is often used without
a storm sash.
Window frames and sashes should be made from a
clear grade of decay-resistant heartwood stock, or from
wood that has been given a preservative treatment.
Examples include pine, cedar, cypress, redwood, and
Frames and sashes are also available in metal. Heat
loss through metal frames and sash is much greater than
through similar wood units. Glass blocks are sometimes
used for admitting light in places where transparency or
ventilation is not required.
Windows are available in many types. Each type has
its own advantage. The principal types are double-hung,
casement, stationary, awning, and horizontal sliding. In
this chapter, well cover just the first three.
The double-hung window is perhaps the most
familiar type of window. It consists of upper and lower
sashes (fig. 4-23 detail) that slide vertically in separate
grooves in the side jambs or in full-width metal weather
stripping. This type of window provides a maximum
face opening for ventilation of one-half the total window
area. Each sash is provided with springs, balances, or
compression weather stripping to hold it in place in any
prevents air infiltration, provides tension, and acts as a
counterbalance. Several types allow the sash to be
removed for easy painting or repair.
The jambs (sides and top of the frames) are made of
nominal 1-inch lumber; the width provides for use with
drywall or plastered interior finish. Sills are made from
nominal 2-inch lumber and sloped at about 3 inches in
12 inches for good drainage. Wooden sash is normally
1 3/8 inches thick. Figure 4-24 shows an assembled
window stool and apron.
Figure 4-24.-Window stool with apron.