Definitive Guide to Replacing Windows

Window shopping

It’s easy to be overwhelmed by all the choices you have to make. Here’s a guide to help you through the buying process.

WINDOWS DO SO MUCH FOR A HOUSE. They let in the light that brightens our rooms; they shut out the bad weather, and, when open, they give us a welcome flood of fresh air. Without windows, our homes would be as dark and depressing as caves. But maybe your windows aren’t doing their job very well anymore—chilling you with cold drafts in the winter and saddling you with high AC bills in the summer. Or maybe they’ve allowed water to dribble in, and now structural repairs are required. Perhaps the insulated glass is foggy or the sashes are stuck. If any of these things are happening, it may be time to invest in new, energy-efficient windows, ones that look as good as or better than what you have. This is not a step to be taken lightly. Windows are prominent features of a facade, and new units should be true to a house’s style and history. And there are a daunting number of decisions to be made, from what a window is made of to how it’s installed, how it operates, and even what pattern of bars you want to divide the glass. Using this booklet, you’ll be able to make sense of the options and learn how to compare products so that you can talk knowledgeably with dealers and installers. Being informed is the best way to reach your goal: to get the best-looking, best performing windows — ones that meet your needs and fit your budget.

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Vitals

LONGEVITY
While a well-made window can easily last 50 years or more, manufacturers usually offer warranties of 10 years on hardware and workmanship and 20 years on the seals that keep insulating glass from fogging. Some makers will even cover exterior-finish failures within a specified time span.

WHERE TO BUY
You’ll find the greatest range of choices and the best advice at window retailers and full-service lumberyards.

INSTALLATION
Leave this to a pro who has experience assessing and measuring a window opening and knows the proper techniques for installing replacement windows.

SAVINGS
Energy Star–certified windows can cut heating and cooling costs by 11 to 37 percent* depending on the type of windows being replaced and your climate zone.

Replacement options

1. Full frame This unit offers the most styles and highest energy efficiency. Because it’s installed from the outside, the same as in new construction, all the existing window’s exterior trim must be removed and some siding may need to be replaced. Doing so allows the framing, flashing, and insulation around each opening to be inspected and upgraded, but it also pushes up the installation cost.

 

2. Insert This unit is installed from the inside, where it fits within the existing window frame, without disturbing the existing trim. Because an insert goes in so quickly, its total cost usually ends up being less than that of a full-frame replacement. Keep in mind that an insert’s frame reduces the size of the window opening—and the amount of light it lets in—by about 1 inch on all sides. Also, an insert may not be an option if the existing window frame is out-of-square or structurally unsound.

Choose Your Style

The way a window operates should be in keeping with the style of house you have.

1. DOUBLE-HUNGThe most popular window in the U.S., and the most appropriate type for traditional house styles, it has two sashes that slide up and down. (On single-hungs, only the lower sash moves.) The screen mounts on the outside. When open, the sashes cover at least half the window opening.

2. CASEMENTIts hinged sash swings out like a door, so air can fl ow freely through the entire opening. Seals tightly to its jamb, making it one of the best types for keeping out the weather. Operates by hand or by turning a crank. When open, the sash is vulnerable to wind and rain. Best for contemporary and Prairie-style homes. The screen mounts on the inside.

3. SLIDERLike a double-hung window on its side, the sashes slide on horizontal tracks—so there’s no lifting —and the sashes always cover at least half the window opening. Best for contemporary house designs. Screens mount to the outside. The lower tracks require regular cleaning.

4. AWNING OR HOPPERIt’s like a casement mounted on its side. An awning window (shown) is hinged at the top and swings out, so you can leave it open when it rains. The screen is on the inside. A hopper window has bottom hinges and swings in. The screen is on the outside. Both types seal well, and with the right muntin configuration they can look good on either traditional or modern houses.

5. TILT-TURNCommon in Europe, this window has special hardware that allows it to tilt in like a hopper or pivot in like a door, depending on which way you turn the handle. The screen mounts outside. It does a superb job of sealing out the weather, but it’s the most expensive window type.

6. FIXED (not shown)Without a sash to open, it only lets in light, so it’s less expensive and more energy efficient than comparable windows with sashes. Best for inaccessible areas, such as gable peaks, or as architectural accents; it can be crafted into almost any size or shape.

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Glass Choices

Double-pane
Compared with single-pane windows, this type is up to 37 percent* better at preventing heat transfer, so interiors stay warmer in winter and cooler in summer. Double-pane windows are also less susceptible to condensation than single pane.

Triple-pane
Adding a third layer of glass cuts heat transfer by another 30 percent, making this the best barrier against cold and condensation. It’s a good choice for north-facing walls, but on a south-facing wall, three panes would cut down on the amount of solar heat that a window lets in.

Laminated
An invisible layer of plastic sandwiched between two sheets of tempered glass creates a pane that’s virtually unbreakable. Use it to foil intruders, muffle sound, and protect your house from earthquakes and hurricanes.

Fun Shapes and Patterns

CLASSIC CURVES
A crown on the casing and ogee lugs on the upper sash elevate the aesthetics of this six-over-one doublehung. (Six-over-one is shorthand for the number of panes in the upper and lower sashes, respectively.)
QUEEN ANNE
This arrangement of tiny panes around a big central pane originated in the Victorian era. Often, the panes were colored to create a stained-glass look at a low price.
ROUND TOP
The curved frame on this double-hung would fit nicely in the confines of a dormer or gable peak.
ARCHED
This playful take on a four-over-two double-hung features a circular fifth pane in the center of the upper sash — just one example of the custom options available in wood.
BULL’S EYE
This arrangement of tiny panes around a big central pane originated in the Victorian era. Often, the panes were colored to create a stained-glass look at a low price.
COTTAGE
Unlike the up-and-down symmetry of a double-hung, the upper sash is one-third the size of the lower one and usually fixed. Fits nicely on Craftsman-style houses.

Materials

Your choice determines a window’s longevity, performance, and looks.

1. Wood Long a traditional favorite, it’s attractive, a decent insulator, and easy to repair. There’s virtually no limit to how it can be customized. Too bad it’s vulnerable to water. Attentive maintenance is the key to how long this window lasts. May be the only option in historic neighborhoods.

2. Clad Wood This is a wood window covered by an outside layer of vinyl or metal, usually aluminum, that virtually eliminates maintenance. Metal cladding is more durable by far. This window shows off wood’s aesthetic qualities on the inside while making use of its insulating properties.

3. Fiberglass This mix of spunglass fiber and polyester resin is rigid, strong, impervious to water, and as good an insulator as solid wood. Some manufacturers offer a wood lining on the interior. About as maintenance free a window as you can get, for less than a comparable wood unit. The downside? A limited number of design choices.

4. Vinyl It’s inexpensive, to be sure, but slowly becomes brittle with age. The frame isn’t stiff, doesn’t insulate well, can’t be repaired, and looks nothing like traditional wood.

5. Aluminum or Steel It’s low maintenance but suitable only for mild climates because of how easily it carries heat outside in the winter and inside in the summer.

How To Buy and Where

To get exactly what you want, pay a visit to a window retailer.

OFF-THE-SHELF
These models, sold at home centers and lumberyard chains, offer low prices and fast delivery—two to three days—but the selection of brands, styles, and sizes is very limited.

MADE-TO-ORDER
You can get the exact sizes, designs, and options you want from window-and-door retailers, high-end lumberyards, or home centers. They can help you select the finishes, glass, and operating type that suits your situation . Lead times are two to four weeks.

SPECIALTY
Need a window with a unique shape or design configuration — say, one made of exotic hardwood with copper cladding? Then reach out directly to a window retailer connected to a manufacturer, one with the skill and experience to handle nonstandard, out-of-the-ordinary requests. Lead times vary, but delivery can take up to eight weeks.

Look for the Window Label

To know how effectively a window halts heat loss or reflects the sun’s heat, among other things, consult a label like the one at right. It contains test results from the National Fenestration Rating Council (NFRC), an independent organization, that you can use to quickly compare the performance of different windows. Not all windows are subject to NFRC scrutiny, so this label is your assurance that a unit meets the local energy code. Here’s the key information, deciphered.

ENERGY STAR
The shaded portions of the map show where a window meets Energy Star criteria. This unit passes muster nationwide.

U-FACTOR
Measures how effectively a window stops heat flow. The smaller the number, the better the performance.

VISIBLE TRANSMITTANCE (VT)
Specifies how much light passes through; 0 is opaque, 1 is transparent. Glass with a VT of 0.60 or more looks clear. A VT below 0.40 gives things a grayish cast.

SOLAR HEAT GAIN COEFFICIENT (SHGC)
Indicates the ability of the glass to block the sun’s heat. The lower the number, the less heat gets in. In the northern zone (see map below), an SHGC of 0.32 or more can offset less-than-ideal U-factors up to 0.30. 

NOTE
Some labels also report the air leakage through a unit in cubic feet per minute per square foot. Look for 0.3 or less.

Energy Savers

How to enhance the way glass performs.

1. Low-e coatings
These transparent, micron-thin layers of metal reflect heat either toward the interior (in cold climates) or toward the exterior (in warm ones), depending on the glass surface they’re fused to. They can reduce heat loss (or gain) by as much as 35 percent.***

2. Inert gases
Air trapped between panes insulates fairly well, but if a gas such as argon is used instead, performance improves by 16 percent.** Xenon and krypton insulate even better than argon.

3. Warm-edge spacers
Standard aluminum spacers conduct lots of heat through the edges of doublepane glass. Nonmetallic, warmedge spacers bring those losses down by 10 percent** and make it more difficult for condensation to form on inside panes.

Know Your Zone

A window suited to Miami isn’t the best for Minneapolis.

THE MINIMUM ENERGY EFFICIENCY STANDARDS set by the federal government for new windows are not uniform across the country; the standards change based on climate zone. Using the information on this map and on the printed label, you can quickly determine which windows are best for your region. Keep in mind that these are minimum requirements — don’t overlook windows that offer even better performance numbers.

*Source: Marvin Windows and Doors | **Source: Cardinal Glass; cardinalcorp.com | ***Source: U.S. Dept. of Energy; energy.gov

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