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Understanding Windows

In addition to providing views of the outside world, windows control the flow of air throughout the interior spaces of your home. Some windows are not intended to be opened, but most windows include one or more movable sashes. Keeping them—and their related coverings—in good working order is the focus. There is more to a window than meets the eye, especially with the older double-hung type shown at right. Concealed behind the side jambs of the frame are heavy sash weights. Connected with a rope-and-pulley system, the weights counterbalance the sashes— making them easier to open—and hold them in any vertical position you wish.

A series of stops fitted to the jambs provides channels in which the sashes slide. Check the top view (below right) and note that although the outside blind stop is more or less permanently affixed, the parting stop and inside stop can be pried loose if you want to remove the sashes. In newer double-hung windows the weight-and-pulley mechanisms are replaced with a pair of spring lift devices. With both types of windows, the lower sash comes to rest behind a flat stool. Its outside counterpart, the sill, slopes so that water can run off. Trim—called casing at the sides and top and an apron below—covers gaps between the jambs and the wall material.

Casement window - Casement windows open and close like a door. In the version shown, muntins separate the panes. However with newer double-glazed casements the muntins— often referred to as grills—snap to the inside of the window to facilitate cleaning or are absent altogether.

Jalousie window - Turning the crank of a jalousie window pivots a series of glass slats. The frames consist of short metal channels at both ends of the slats. The glass-to-glass joints tend to leak air, so jalousies usually are used only in breezeways, porches, and other unheated zones.

Sliding window - As with double-hung sashes, sliding sashes (also called gliding sashes) open up only 50 percent of the total window area for ventilation. Some sliding windows have one fixed and one sliding sash, as shown. With others, both sashes slide along tracks. Sliding windows can be made with wood, metal, or vinyl. In most models, the movable sash slides in the bottom track; in some, it glides on an upper track. An older window’s track may be a simple groove made of wood. Newer windows have metal or vinyl tracks, and the sash may have rollers for smooth operation.

Awning window - An awning window works in the same fashion as a casement window, but the sash tilts outward from the bottom. Some awnings slide downward as they tilt, so that you can open them to a nearly horizontal position for maximum cooling airflow. An awning window opens with a side-mounted or two-armed mechanism, operated by a crank, sometimes called a roto-handle. Hinges usually can be disengaged so you can easily remove the sash.

Freeing a Balky Sash

When a double-hung window binds or refuses to open, don’t try to force it. Take a look around the sash, both inside and out. Chances are you will find that paint has sealed the sash shut or that a stop molding has warped. The steps shown here will enable you to gently pry and free the sash, preventing damage. If the top sash is painted shut, you may choose to leave it that way, unless you need to move it for cleaning.

Tools: Sash knife or utility knife, flat pry bar, and hammer.

1. Break the paint seal. To break a paint seal, use a sash knife, which is specially designed for this purpose. Or run a sharp utility knife several times between the sash and stop. Be sure to cut through the paint at every point.

2. Pry the window open. Pry from the outside edges with a pry bar and a protective block of wood. Take your time, using gentle to moderate pressure at several points. Alternating sides, work inward from the edges until the sash pops free.

3. Spread the stops. If a sash is binding between its stops, try separating the stops slightly by tapping along their length with a hammer and wooden block that fits tightly between the stops. If the binding is severe, you may need to pry the stop off and nail it in a new position.

4. Lubricate the sash. Once you get the window moving, scrape or chisel any built-up paint off the edges of the sash or between the stops. Lightly sand its jambs; then lubricate with a candle or with paraffin, paste wax, or bar soap.

Other Double-Hung Mechanisms - Another type uses a tension spring—a flat metal strap that attaches to a spring-loaded drum unit in the sash. Finding replacement drum units may be difficult. A friction sash is made of vinyl or aluminum; it grabs the sash tightly enough that it does not slide down when raised.

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