Choosing Windows

	Window Styles
	Materials
	Construction
	Window Hardware
	Window Orientation and Size

Windows come in many shapes, sizes and types and are made from a variety of materials. How do you select the right ones? There are several criteria to consider—your budget, your home's style and how you want the window to perform. Think about the relative importance of ventilation and security and how easy it should be to maintain. And, decide whether you want to emphasize the window as a focal point or have it serve in a more practical manner.

Windows are either fixed or operable. These illustrations show the common varieties and will give you basic information about how they perform:

Click here for a complete listing of fixed windows

Click here for a complete listing of operable windows

Windows are made from a variety of materials, including wood, aluminum, steel, vinyl and fiberglass—or from a combination of these materials. In general, those that offer better weather protection cost more, but they pay off in low maintenance and energy savings.

• Wood - Wood tends to be the most popular window material, particularly for the parts of a window that are seen from indoors. Wood doesn't conduct cold or allow for condensation as much as other materials. However, wood is subject to shrinkage and swelling, so it will warp and rot over time—especially on the exterior—unless it is protected.
  
  Wood windows typically come unfinished unless you order them otherwise. If you intend to paint them, save work by purchasing them already primed on the exterior and/or interior surfaces of the frame and sash. Or, you may be able to eliminate painting altogether by buying them pre-painted in some standard colors by certain manufacturers.
  
  
• Clad-wood - You'll find that many of today's windows are wood inside and clad on the outside with a tough, attractive exterior jacket of extruded aluminum or vinyl. The cladding, available in a few stock colors, covers both sash and frame; it will keep windows virtually maintenance-free for years. With vinyl, the color permeates the material, so scratches don't show. Aluminum will scratch, but it is tougher, available in a wider variety of colors and easier to paint (though neither vinyl nor aluminum should require painting). Neither type will rust or rot.
  
  
• Aluminum - Aluminum windows are more durable than bare wood—also thinner, lighter and easier to handle. They are insulated with a thermal break of extruded vinyl and sometimes also foam, which reduces heat loss and condensation. Finishes protect the aluminum from corrosion, but deteriorate in coastal areas due to the salty air.
  
  
• Vinyl - Vinyl windows are made from rigid, impact-resistant polyvinyl chloride (PVC), with hollow spaces inside to make them resistant to heat loss and condensation.

Most wood windows come prehung in complete frames that fit into a rough opening in the wall. They are attached with nails driven through the exterior casing, or brickmold, on the outside and through the jambs on the inside.

Vinyl or aluminum windows and some wood windows with a vinyl or aluminum cladding have a factory-installed nailing flange on the outside that you attach to the perimeter of the window's rough framing.

All operable windows come equipped with hardware—the mechanisms used for opening and closing the sash, the latches and so forth. Here is a closer look at key types:

• Cranks - Casement, awning and hopper windows utilize cranks for opening and closing. (Older types used push-bar operators.) Some manufacturers offer cranks in nonmetallic finishes (notably white) and some new types have fold-down handles that make them less conspicuous.
  
  
• Latches and locks - Latches on the frame are used to hold the window tightly closed. On hinged windows, two are recommended on tall or wide frames. On double-hung windows, sash locks pull together the upper and lower sash to minimize drafts. Keyed sash locks can improve security.
  
  On sliders, look for security locks to keep the operable sashes from being jimmied open.
  
• Counterbalances - On double-hung windows, the sash is counterbalanced on the sides by weights or other counterbalancing mechanisms, such as torsion screws. In some replacement windows, friction may be all that holds the sashes in place.
  
• Sliding mechanisms - Most sashes of aluminum and vinyl windows are lightweight enough to slide in the sill tracks. But large, door-height sashes must be supported by rollers.

Window Placement Guidelines When gauging the placement of a window, consider not only the view, but how the room is used. For example, in a kitchen, the sill should be above the level of the counter; in a living room, 10" to 14" from the floor so you can view the outdoors from a couch.	Illustration of sitting height placements. Click the image for an enlarged view. Illustration of standing height placements. Click the image for an enlarged view.

The view out a window is as important as how much light and ventilation the window provides. Windows connect us to the outdoors and enhance the sense of interior space. For this reason, the placement and size of your windows—and what you'll see from them—is no small consideration.

Where your windows are placed, how large they are and what type they are have a significant effect on the amount of light and ventilation they provide.

A south-facing window lets in the most light and is desirable in all but the hottest climates; a north window provides soft, diffuse light. Because of the low angle of the sun in the morning and late afternoon, light from east- and west-facing windows can be too intense.

Unfortunately, glass is not nearly as good at conserving energy as an insulated wall, so glazed doors and windows can be responsible for a major part of a home's energy loss if they're not well chosen. Storm windows and doors and window coverings can help retard heat movement, but the surest and most effective way to save energy is to utilize high-performance glazing.

An example of high-performance glazing. A cross-section of high-performance glazing shows two panes of glass with a space in between. In some cases, the space is filled with argon, or a similar inert gas, which serves as an insulator. In addition, a low-emissivity coating deflects outside ultraviolet rays while retaining indoor radiant heat.

Two important ratings to check when buying windows and glazed doors are the R-value and the overall U-value. An R-value measures a material's resistance to heat transfer; the higher the R-value, the better the insulating properties of the glazing. The U-value measures overall energy-efficiency. It tells you the rate at which heat flows through the entire window or door, frame and all. The lower the U-value, the more energy-efficient the window or door. An average U-value is fine for warm climates; in cold climates, a lower U-value is worth the premium you are likely to pay for it.

Insulating glazing typically has two, or sometimes three, panes of glass sealed together with either air or argon gas trapped between them to act as an insulator. Some units have a plastic film suspended between two glass panes. If the unit is properly sealed, condensation shouldn't occur between the panes; sometimes a drying agent (called a desiccant) is used in the spacer (the strip inside the panes, which helps keep them apart) as added insurance against condensation. One important reason for buying windows and doors with a strong warranty is to ensure that they will be backed if the seal fails and condensation occurs (there is no easy way to get rid of condensation in dual glazing).

Click here to learn more about energy-efficient windows.

You will discover that there are also a number of glass products on the market for special uses, including safety glass and stained glass. Here is a closer look at both high-performance and specialty glazing:

• Low-emissivity (or low-e) glass - Low-e glazing has a film applied to one of the glass surfaces or suspended between the panes. This coating or film allows light in, but prevents some solar rays from being transmitted through the glass. A Low-e coating can help keep your home cool on a hot day by blocking longer-wave radiant heat from entering, and on a cold day it can prevent the radiant interior heat from escaping through the glass. Some Low-e coatings combine these two functions. Low-e coatings also block ultraviolet rays, and reduce the fading of carpets and upholstery.
  
  
• Tinted glass - Usually given either a bronze or gray cast, tinted glass reduces glare and limits the amount of light and heat from the sun (solar gain) in your home.
  
  
• Safety glass - Required by certain local building codes for certain situations, safety glass is always a good choice if there's any risk of a person walking through a window. Safety glass is available tempered, laminated or wire-reinforced. Tempered glass is heat-treated during the manufacturing process and crumbles if broken rather than shattering. Laminated glass has a film of plastic that holds the glass together if broken.

You can install small stained-glass panels in the same way you would install ordinary clear panes. Large panels need additional support for permanent installation; fit them into their own routed wood frames, or block their edges on both sides with wood strips nailed to the sill and window frame. Be sure to set the panel in glazing putty and caulk all outside joints.

Originally published in Lowe's Complete Home Improvement and Repair ©2000 Sunset Publishing Corporation, Menlo Park, CA 94025