rom an Architect’s perspective, windows are one of the most important elements that goes into a typical home, and the choice of which windows to use should not be taken lightly. Windows perform many important functions in residential buildings – they are part of the exterior envelope that keeps inhabitants separated from the elements, they provide a visual connection with the outside world, they let in critical natural light, and they can be used to help ventilate or passively heat and cool a space. We also expect them to look good, function flawlessly, last forever, and coordinate with the exterior and interior materials.
Modern building codes have minimum energy efficiency standards for windows, and these have been getting more stringent in recent versions of the code. Quality windows are a critical component in an energy efficient home, since most of the heat loss (and gain) in a well insulated building occurs through windows and doors. However, good windows are expensive, and cost is usually a major factor in the deciding which type of window to use. I always advocate for using the best quality windows that the budget will allow, even if it means compromising elsewhere.
The residential window business is highly competitive and there are constant innovations that Architects and builders try hard to stay current on. Here are my observations and opinions on some of the window options out there.
Vinyl windows have become something of an industry standard in lower to mid level homes, and are even sometimes used in more upscale custom homes. Because they are the most affordable of the pre-manufactured window options and are relatively easy to make in custom sizes, vinyl windows have become extremely popular, especially for replacement windows. On the plus side, all but the cheapest vinyl windows are reasonably energy efficient and meet minimum code requirements. They also won’t rot or require any maintenance.
In my opinion, vinyl windows have many disadvantages – the frames sag over time, the profiles are usually clunky and unattractive, the grids look fake, and vinyl as a material is environmentally harmful and contributes to bad indoor air quality. Sun deteriorates vinyl over time, leading to it becoming weak and brittle. Until recently, vinyl windows were available in any color you wanted, as long as you wanted white or tan. Now Jeld-Wen has vinyl windows available in 8 standard colors with a custom option to have them painted any color. I don’t advocate using vinyl windows except when the budget is super tight or in a replacement situation where custom sizing better windows would be cost prohibitive.
Vinyl clad wood windows are better than pure vinyl windows because the frame is made of wood with a protective vinyl cover on the exterior portion of the window. While they still look like vinyl windows on the outside, the interior is natural wood and it is hard to tell them from true wood windows. They combine the low maintenance of vinyl with the beauty and strength of wood. As you might expect, vinyl clad wood windows are priced in the mid range and are a good choice when the budget allows a quality upgrade from pure vinyl. Some companies offer Fiberglass Cladding in lieu of vinyl. Fiberglass is a more durable option that is available in more colors than vinyl.
Aluminum clad wood windows are the standard of quality in modern residential construction. They take the time tested all wood window that has been used in quality homes for the last 100 plus years and eliminate the largest disadvantage – exposed wood on the exterior that deteriorates quickly and requires frequent maintenance. Modern clad wood windows are built to high standards of energy efficiency and their performance can be further upgraded by opting for different glazing choices. The exterior cladding is formed to different profiles, depending on the manufacturer and the product line you choose. Cladding color choices are extensive, and the best windows have 20 – 30 year warranties on the paint used for the cladding, which makes them maintenance free and very long lasting. In my mind, clad wood windows are the obvious choice when superior energy performance, longevity, and good looks are important considerations. For a photo sequence showing the installation of aluminum clad wood windows, see Large Window Installation.
All wood windows perform similarly to clad wood windows, with the exception that the exterior is exposed wood rather than clad with aluminum. While the energy performance of these units will be the same, they are more susceptible to weathering and require frequent painting or staining. They look great, especially on rustic and some traditional style homes, but I would only recommend using them when the aesthetic of the home requires. If all wood windows are used, it is a good idea to provide large overhangs or other means to protect them from sun and precipitation. Humid climates may necessitate using more durable (and costly) wood species, such as Honduran Mahogany, Verante or Teak.
Hurd, a Wisconsin manufacturer of quality windows, is currently marketing a hybrid window called the H3. It combines aluminum cladding, a vinyl core frame, and wood interior. Installed, it looks just like a clad wood window because the vinyl is used in places where it doesn’t show. Advantages of using vinyl are increased stability, better rot resistance, and lower cost. I have yet to see these windows installed on a project, but it is an interesting idea and may be a good option for projects that require quality windows at a mid level price point.
Windows are an important architectural and functional element of any home. If you are building a new home, an addition, or replacing old windows, buy the best you can afford and pay careful attention to installation details. It may be worth checking for federal, state, or utility company incentives for energy efficient upgrades.
Tom Russell, Project Architect, LEED AP
Hendricks Architecture, mountain architects in Sandpoint, Idaho. Windows are a big part of our initial designs, helping the overall aesthetics, curb appeal, views, energy efficiency, UV control, and other considerations.