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Material and Construction Options for Windows

Windows can make a dramatic statement in a home’s design. In addition to choosing window styles, there are many material decisions to be considered before buying.

Credit: Pella Corporation

When it comes to windows, it’s the sash and frame that you’re going to see. The selection of sash or frame material goes beyond aesthetics, however. Window manufacturers typically specialize in a given material, so selecting your sash material may limit your choice in makers. Take the time to weigh the pros and cons of each, along with the service and warranties behind each manufacturer, because windows are among the greatest single investments you will make in your home.

Wood
Wood is the standard material for residential windows. It can be painted or stained, and is strong and easy to work with. Ease-of-use makes for easier custom windows, which is why highly detailed designs are typically made from wood. With regard to energy efficiency, few sash and frame materials are better insulators than wood. The only downside to using wood windows is that they require regular maintenance. Peeling paint is more than an eyesore, it’s a sign that wood is being exposed to weather, which will ultimately cause it to rot. A small number of high-end producers use rot-resistant species like mahogany, but most domestically manufactured windows are made from less-resistant species such as pine. That said, a properly maintained wood window could last hundreds of years.

Vinyl

Vinyl Windows: Then and Now
Early vinyl windows had problems with thermal expansion. When temperatures changed, the vinyl sash would expand or contract at a very different rate from the glass. As a result, the window fit poorly, leaked, or cracked. Such problems have been on the decline, because modern vinyl is more durable and dimensionally stable than the materials that were used 15 or 20 years ago. Vinyl is also commonly used as cladding on wood or aluminum windows.

Vinyl windows are inexpensive, durable, and relatively energy efficient. They often look chunkier than wood or metal windows because vinyl isn’t strong enough to be made into ultra-thin parts. The other problem is that the texture is unmistakably plastic. On the other hand, except for washing the glass, vinyl windows are virtually maintenance free. You can’t paint them, but you can get them in a number of different colors. What’s more, the color goes all the way through the material, so dings and scratches are nearly impossible to see.

Steel
Steel windows are common in industrial buildings. While they have never been popular for residential use, they do appear in pre-war modernist homes, and basement windows set in wells. The advantage to steel is that it’s very strong. As a result, glass area can be maximized since window parts can be made extremely thin. Steel is durable, but not maintenance free; it will rust if you don’t keep paint on it. Steel is also a poor thermal insulator, so heat escapes through the sash and frame, while moisture condenses on interior surfaces.

Aluminum
Aluminum windows have many of the qualities associated with steel windows, except you don’t have to paint them, and they won’t rust. Instead, aluminum windows are available with a number of anodized or baked-on finishes. The problem with aluminum windows, however, is that they aren’t very energy-efficient. Aluminum is a good thermal conductor, so in cold weather heat drains out through the sash and frame, as moisture condenses on interior surfaces. Better quality aluminum windows are equipped with thermal breaks that separate the interior and exterior surfaces of the window.

Modern windows take advantage of multiple materials. Here, a wood casement window’s exterior is sheathed in vinyl for weather resistance and reduced maintenance. On the interior, the exposed wood can be painted or stained.

Credit: Andersen Corporation


Fiberglass
Fiberglass has been around for a long time, but it’s a relatively new material for windows. Long used for items like boat hulls and auto bodies, it has an excellent record for durability. Fiberglass is strong, so hollow parts can be made without the stiffeners required for vinyl. This allows manufacturers to produce higher efficiency windows by filling voids with insulation. In fact, insulated fiberglass windows are even more energy efficient than those made from solid wood. You can paint fiberglass windows, but they won’t deteriorate if the finish wears away. The downside to fiberglass windows, however, is their cost compared to similar windows made from other materials.

Composite
The sash and frame of a composite window are made from more than one kind of material. This allows the manufacturer to make the material fit the task. For example, the inside surfaces of the window might be made from wood, so it could be painted or stained. The outside surface, however, could be made from a more weather-resistant material like vinyl or aluminum. The classic example of this is a wood window with vinyl or aluminum cladding. A newer type of composite window has exterior parts that are made from a blend of wood chips and recycled plastic. These wood/plastic blends can be painted, but are impervious to rot if the paint fails.

Credit: Renovate Your World