Windows are made from wood, aluminum, steel, vinyl, vinyl-clad wood, aluminum-clad wood, fiberglass, and composite materials. Confused? Most people are, particularly when it comes to deciding which one is best for their house. Each material has both positive qualities and drawbacks that should be considered when choosing windows. Here is some background on several common window materials.
Wood: For centuries, window frames have been made of wood, and it still remains a leading choice for premium windows. Most commonly, windows are made from Ponderosa pine or Douglas fir, but they may also be white pine, redwood, cedar, or cypress. The wood must be clear, meaning it contains no knots that could weaken the wood or be difficult to paint or stain.
Wood has better insulating qualities than metal. Moreover, water will not readily condense on wood, as it is prone to do on metal. Extensive condensation can lead to wood rot problems around the window.
Wood-framed windows may be double-hung, sliding, casement, or any of the other varieties. They can be stained or painted to match your house’s décor, which is one advantage over aluminum windows, which cannot be painted. On the other hand, wood windows must be stained or painted at regular intervals to protect them from the elements.
Most wood windows are made in a variety of stock sizes. This system works well in new construction where carpenters frame the rough opening for known window sizes. But if you want to replace a window, it may be difficult to find the same size because different manufacturers have different stock sizes.
Aluminum-clad wood: This combination is a popular choice among homeowners and professionals because it combines high quality materials with low maintenance requirements. The exterior side is covered with aluminum that comes in a variety of colors baked into the finish. It provides excellent protection against the elements and does not need painting. The interior side is made of wood and can be either stained or painted to accompany the home’s décor.
Vinyl-clad wood: These windows are similar in style and function to aluminum-clad wood windows, only with a vinyl exterior. The vinyl comes in a more limited choice of colors, such as white, brown, and beige, but is highly resistant to the elements.
Aluminum: These light metal frames are strong and generally less expensive than wood frames. Lower quality aluminum windows readily transfer cold, making them a poor choice in areas of wide temperature swings. Newer models have a strip of plastic or rubber in the frame called a thermal break that is designed to reduce heat or cold conduction.
Aluminum windows in recent times are commonly finished with a baked enamel paint in white or bronze. Older aluminum windows were anodized, which means given a protective film coating by electrolysis. These frames will eventually corrode, however, especially in a salt air environment. Periodically coating the frames with auto wax can help prevent corrosion.
Steel: Many older homes have steel window frames, but these windows are currently found primarily in commercial buildings where higher fire safety standards are required. Although durable, they require considerable maintenance, including regular painting. If not painted, they will soon rust.
Fiberglass: These tough window frames are made from materials similar to the composite bumpers used on many cars today. The frames are made from a fiberglass/composite material, usually a polyester resin, that is strong, maintenance free and energy efficient. Although usually higher priced than vinyl windows, fiberglass frames can be painted, something that cannot be done with vinyl.
Vinyl: These windows came into their own as energy-conscious homeowners began looking for ways to retrofit their homes and add double paned insulated glass. Homeowners could suddenly change only parts of a window or the whole thing, depending on their needs. If the double-hung window tracks were worn out, they could install just vinyl tracks with built-in counterweight springs. Or they could put in new sashes if the frames were in good condition, or replace the whole window unit.
Vinyl frame windows usually run about half the price of wood windows. A honeycomb effect in the extruded vinyl frame provides insulation through dead air space. A chief advantage of vinyl windows is that they can be readily constructed to fit any opening, making them a top choice for inexpensive window replacements. The colors are limited but they do not require painting.
But not all vinyl frames are equal. Some manufacturers buy the vinyl extrusions as cheaply as possible and then assemble the windows. To judge quality, look at the extrusion in section. The best ones will have up to 13 chambers inside divided by webs. Lesser ones will have only four or five chambers. While the chambers offer insulating qualities, it’s the webs that provide the strength. The more webs, the stronger the window.
Storm windows are designed to both protect the windows and further reduce air infiltration. They are often custom designed to fit precisely over your existing windows and may be single or double paned, depending on your energy saving needs. Storm windows offer an added benefit of reducing exterior noise, particularly if they are double paned.
Storm windows are made from aluminum, steel, wood, or vinyl. They may also be wood that is vinyl or aluminum clad on the outside, with colors to match your house’s exterior finish. Some come with sliding windows that have screens, allowing you to open your windows for fresh air without having to remove the storm windows during the summer months.
Windows and Codes
Before installing new windows in your home, check local code requirements. Local codes overrule national codes, and they may differ from some basic national regulations.
Minimum window requirements in a habitable room are as follows:
- 20 inches wide
- 24 inches high
- 44 inches maximum from bottom of window opening to floor
This requirement provides sufficient room for people to escape in case of fire and for a firefighter to pass through the window while wearing an oxygen pack.
Safety glass must be used in certain situations. Safety glass includes laminated glass with a minimum 7/32-inch plastic interlayer, approved plastics, or tempered glass. Safety glass is required in the following areas:
- Sidelights within 12 inches of a door
- Windows within 24 inches of a door
- Any glass less than 18 inches from the floor
- Sliding glass doors
- Framed and frameless glass doors
- Bath and shower enclosures.
Tempered glass must also be used if all (not just one, but all ) of the following conditions exist:
- Window area is greater than 9 square feet
- Top edge of glazing is more than 36 inches above the ground or floor
- Lower edge of glazing is less than 18 inches from the ground or floor
- Window is within 36 inches of a walkway.
Other general codes rules state that:
- Glazing in a habitable room must equal 1/10 of the floor area
- Ventilation (open window area) for a habitable room must equal 1/20 of the floor area
- No window is permitted in a wall less than 3 feet from a property line.