Double and single-hung windows
Double-hung windows consist of a lower and upper sash, each working independently from the other. Typically balanced by ropes or chains, the sashes move up and down and can be set open at any position. A modern, double-hung window uses springs on each side of the sash to hold the sash in place. A single-hung window, similar in principle, differs only in that the top sash is fixed, so only the bottom sash is moveable. Because the two windows become doubled up when open, only half of the actual window space allows air to pass through, resulting in a maximum of 50 per cent of the total windowed area being used for ventilation.
The casement window is popular in today’s home construction. Hinged at the sides and able to swing in or out like a door, casement windows feature sashes that open and close by a crank, handle or a push bar mounted on the frame. Casement windows higher than 5’ are more difficult to open and close, operated by a single crank at the bottom of the window. Typically, screens are located on the interior of the window frame as the window pivots outward. The benefit of using a casement window is that 100% of the total windowed area can provide ventilation.
Generally a lower-end style, the sliding window features two or more windowpanes that pass each other on a horizontal track. Sometimes one of the sashes is fixed, allowing only one side to be functional. As with its double-hung counterpart, only 50% of the windowed area fitted with sliding glass can provide ventilation. Another notable disadvantage of sliding windows is that they are usually constructed from aluminum, and replacement parts such as rollers or corner retainers can be difficult to find.
Awning windows feature one or more top-hinged, outward swinging sashes. The sashes extend out at an angle and look like an awning when open and 100 per cent of the total window area can provide ventilation. There are four variations of awning designs:
- Top-hinge style: Opens inward instead of outward.
- Utility: Hinged at the bottom, usually found in basement windows; sometimes called a “hopper” window.
- Jalousie: Features a series of horizontal glass panes that open outward.
- Transom: Constructed above doors or other larger windows, can swing inward or outward.
A fixed window consists of a frame but does not offer any moveable sash components. Picture windows, bay windows and round-top windows are examples of typically fixed styles. Providing no ventilation, fixed windows are often flanked by vertical casement windows, which provide some ventilation.
Also called a “roof window,” a skylight can either be fixed or awning style and is available in several designs including flat, vaulted, ridged, pyramid and dome style. Skylights offer extra light and ventilation (if not fixed) and are often used in cathedral ceiling applications. Functional skylights do not open as wide as awning windows in order to keep rain out while 30 to 50 per cent of the windowed area can provide ventilation.