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Window Installers (From CHECKBOOK, Fall 2013/Winter 2014)
Go to Updated Ratings of 31 Puget Sound Area Window Installers


Window Installers

While you won’t recover the cost of replacement windows from the resulting energy savings, there are other good reasons to replace old windows: If they are ugly or deteriorating; if they are hard to wash; or if you want to minimize your home’s impact on the environment. You might also want to install a new window where there was no window before. 

The kind of windows you buy will determine the appearance, amount of light admitted, comfort and energy savings you achieve, and how long they will last. 

Salespersons may provide data on energy savings, but check their claims using the tools described in this article. You won’t be able to get verifiable data about durability, but you can learn quite a bit about window construction by talking to different salespersons and reading manufacturers’ literature. Also, compare warranties. 

There are, unfortunately, a lot of unhappy window customers. As our Ratings Tables reveal, some companies were rated “inferior” by 30 percent or more of their surveyed customers. But there are also some very highly rated installers. 

Get several price quotes. Price differences are big. For one very specific replacement job, we received price quotes from area companies that ranged from $2,100 to $8,256. 

U-factors, E-coatings, Argon, Krypton—we’re not talking about computer chips or Lex Luthor’s latest weapons against Superman but rather windows. Modern windows are technological marvels compared to the old window/storm window combinations. They are easy to clean: no need to teeter on high ladders; simply tilt them in or remove them and wash them inside your house. And modern windows provide such good insulation that the window area feels about as warm as the rest of the house. 

Although window sellers may make extravagant claims about how much new windows will reduce your energy bills, even new windows that replace old, very drafty ones won’t “pay for themselves” in energy savings. 

But you still may value new windows for other reasons. Replacing drafty windows that admit drafts on cold nights will let you maintain a more constant, comfortable temperature and humidity level. And many consumers want to replace old windows with new, energy-efficient ones to minimize the environmental impact of their homes. 

In addition, you might want to replace old windows that have become unsightly or difficult to open and close. 

The benefits for homeowners have created opportunities for businesses, which some have exploited with high-pressure sales tactics, exaggerated and confusing energy claims, and substandard installations. 

This article will help you explore your window choices and find a high-quality, reliable window installer. 

Which Windows to Buy? 

A good way to learn about window options is to visit installers’ showrooms. Let salespersons describe window features and the different installation techniques. Visit several showrooms and listen to pitches from more than one salesperson. Pick up copies of manufacturers’ catalogs and look through them when you get home. But don’t agree to buy anything on these exploratory visits. 

If you are adding or enlarging windows, or doing new construction, you can benefit from creative ideas in magazines and books and on the Web. 

There are many features to consider when selecting windows and the company that installs them. You will have more to think about, of course, if you are adding windows or doing new construction than if you are simply replacing existing windows. 

You’ll want windows appropriate for the architecture of your house and your neighborhood. If you live in a historic district, or if your neighborhood is governed by a homeowners association, find out what is allowed. Preservation officials or homeowners association rules might ban vinyl windows, for instance, or specify certain types of window muntins (grids). Ignore these rules at the peril of having to tear out what you install. 

Assuming you aren’t constrained by neighborhood requirements, you’ll have to decide among various types of windows and construction materials. 


The most common styles are— 

  • Double- and single-hung. Double- and single-hung units look the same, but on single-hungs only the bottom sash moves. These windows can be cracked for ventilation and locked in that position with window pins for security. Tilt-in models are made to be easy to clean on both sides. The marginal downside is that only half the window area can be open at any time, while other styles open fully for greater ventilation. 
  • Casement. These outward-swinging windows open fully for ventilation, and the view isn’t obstructed midway by the frames of two sashes. The weak link is often the cranking hardware, particularly on large units. Because casement windows also provide too-slow escape routes in the event of fire, they shouldn’t be installed in bedrooms. 
  • Awning and hopper. Awning-style windows swing out at the bottom; hoppers swing in at the top. Both types of rectangular units (which look like casements turned on their sides) can be inset at the top of foundation walls to provide light and ventilation to basements. 

Figure 1—Types of Windows

Frame Material 

All styles are available in different materials, including wood, vinyl, fiberglass, and, to a lesser extent these days, aluminum. You may base your choice on appearance, cost, energy efficiency, maintenance, or a combination of factors, but the most significant differences in quality among windows are not materials but in how well they are constructed. A cheaply made wood frame won’t hold up as well as a top-quality vinyl or fiberglass frame, and vice versa. Aluminum is no longer a popular option because it is a poor insulator, requiring disconnects (called “thermal breaks”) between the inside and outside frame surfaces, and may still be subject to condensation in cold climates—even when the new double glazing prevents it on the glass. 

Although there is a very wide price range for each type, vinyl is on average the least expensive, wood is mid-range, exterior-clad wood is more expensive, and fiberglass tops the list. A quick rundown of other pros and cons— 

  • Vinyl—The first generations of vinyl windows had problems with expansion and contraction during temperature swings. Modern formulations have greatly reduced that problem, although most manufacturers stick to light colors and no longer offer dark brown frames because they absorb too much heat from the sun’s rays. Frames with welded corners are the sturdiest and most energy efficient. 
  • Wood—This traditional choice is a good natural insulator that can be milled to provide classic architectural detailing—even styles that comply with historic districts and neighborhood association restrictions. Many come factory primed, ready for a finish coat in any color. That versatility is also the main drawback: the need to scrape and repaint every few years. Having vinyl cladding on all exterior parts of wood windows increases the price and may limit your ability to change color schemes over time, but it can eliminate the need for regular repainting. 
  • Fiberglass—This grainy synthetic is considered the most durable and strongest type, making it a good choice for large panes of glass and assemblies of several windows. It can be extruded into slimmer profiles than vinyl, making it a good choice for frame-plus-sash replacements. It can be painted to suit and is available with wood veneer facings on the interior side. 

In addition to choice of the material for windows, you’ll need to decide on other visible details. You will find windows with thicker or thinner frames, more or less substantial muntins, and various types of hardware. 

Which Replacement Technique? 

If you are replacing old windows, you need to choose one of three basic types of installation: 

Sash Pack 

If your frames and trim are in good shape and you mainly want to get more energy-efficient window glass, consider a sash pack, the least expensive option. In a typical installation, old sash and tracks are removed, and jamb liners are installed against the sides of the window frame. They seal and secure the new sash. 

Major manufacturers may carry over 100 stock sizes, fabricate custom sizes, and offer many colors, cladding, tilt-in hardware, divided-light grills, and other features. Some companies market sash pack installation as a do-it-yourself job. 

Frame and Sash 

This common, more expensive replacement option consists of a fully framed sash unit that slips into the existing window frame after the old sashes and tracks are removed. In this case, again, the existing frame and trim are left in place, so they must be sound; framed replacements can’t compensate for major leak damage. 

The key to this option is the amount of space between the old and new frames. A good match will produce a close fit, with no two-by-fours added to pack out and significantly downsize the opening. Glass area may be reduced by an inch or so, but not by several inches. Small gaps between the old and new frames are fine; they can be insulated and existing trim built up with narrow strips that blend into the overall facade. Installers should tuck in loose-fill insulation or spray in low-expanding foam. (Standard foam has enough pressure to bow the jambs.) On the other hand, if the fit leaves large gaps, they typically require wide boards or aluminum panels to bridge the openings; the result looks out of scale and doesn’t fit in with the facade. 

Full Window 

This start-from-scratch option is the most expensive approach. The old unit is pulled out, any damaged framing repaired or replaced, and then a new window installed as if it were new construction. This is the only option if the framing needs to be significantly altered. It also avoids the reduction in glass area produced by the frame-and-sash approach. 

If your old windows are stock sizes (most are), you shouldn’t have to spend extra for custom construction. Window manufacturers’ catalogs often list at least 75 stock sizes just for double-hungs. For the rough opening (the distance between framing members that allows for shimming space), typical widths start at 24 inches and increase at four-inch intervals up to 48 inches. Typical heights start at 36 inches and range up to 72 inches. 

How Much Energy Will New Windows Conserve? 

By choosing the right windows, you can conserve energy. That saves you money, saves world resources, and reduces your contribution to pollution. In addition, preventing heat from escaping your home will make your home more comfortable by eliminating cold areas around windows. Modern windows are constructed to reduce your home’s heat loss, enhance its heat gain from the sun on cold days, and suppress its heat gain on hot days. 

Heat transfers in three ways: 

  • Conduction, the movement of heat through solid material like glass or aluminum, the way heat reaches your hand through a drinking glass when you pour hot tea into it. 
  • Convection/air infiltration, the movement of heated air and other gas (or liquid), the way hot air rises out of an oven when the door opens. 
  • Radiation, the movement of heat without conduction or convection, the way warmth reaches your face as you sit by a sunny window even on a cold day. 

Modern windows are typically constructed using two or three panes of glass, with air or an inert gas such as argon or krypton filling the space between panes. The air or gas is an insulator, more resistant to the passage of heat than solid glass. In many windows, one or more panes are glazed with a thin, transparent film of metal that reduces the pane’s ability to radiate heat; this is called a low-E coating. In high-quality windows, the materials of the frame itself are poor heat conductors. The spacer material that separates the panes of glass around the edges is another issue. Aluminum, a common spacer material, is highly conductive, transferring heat from pane to pane; rigid foams and other less conductive materials replace aluminum in some windows. 

Several factors measure the energy conservation performance of windows. 

The U-factor, which measures the ease with which heat passes through the window, is sometimes calculated for the glass area only. That is not very useful; you should get information on the U-factor for the entire window assembly. 

You want windows with a low U-factor. A single pane of glass in an aluminum frame might have a U-factor of about 1.3; some high-tech windows have U-factors as low as 0.1. 

When the outside temperature is cold, heat passes out of your home through closed windows in various ways, all of which contribute to the U-factor. For example, with a double-pane window heat might be absorbed and conducted through the inner glass, absorbed by the gas that fills the space between the panes, circulated to the outer pane by movement of the gas, absorbed and conducted through the outer pane, and absorbed and carried away by the air that moves along the outside of the window. Simultaneously, heat might be absorbed by the glass and radiated to the outside. Heat might also be absorbed by the inner glass pane, conducted to the outer pane by the spacing material that separates the two panes around the edges, and then radiated to the outside by the outer pane. In addition, heat might be absorbed by the window frame and conducted directly through it to the outside, where it radiates away or is absorbed by the outside air and moved away by convection. The U-factor measures the ease with which all these and other heat-transfer processes occur. 

The Solar Heat Gain Coefficient (SHGC) expresses the fraction of the sun’s radiation that is admitted through a window, taking into account both radiation directly transmitted and radiation absorbed by the glass or frame and then re-radiated inward. A high SHGC number is desirable in cold weather for windows that receive a lot of direct sun exposure. The heat from solar radiation a home takes in through a south-facing window may be great enough to more than offset heat loss through the window—making the window better than a well-insulated wall from an energy conservation standpoint. On the other hand, a high SHGC number in windows that receive a lot of direct sun exposure is undesirable in hot weather; the heat from the solar radiation raises indoor temperatures, forcing air-conditioning systems to work harder. The ideal solution is to have a high SHGC on south-facing windows, which get direct exposure to the sun when the sun is low in the sky in the winter, and then protect these windows in the summer with a roof overhang that obstructs sunlight when the sun is high in the sky or with fully leafed-out deciduous trees. 

In general, as U-factor goes down (when more effective low-E coatings are added to the glass), so does the SHGC measurement. For a south-facing window you may decide to sacrifice some ability to prevent heat loss in favor of a window with high solar heat gain potential. A window with a single clear pane of glass with no special low-E coating, might have an SHGC rating of about 0.70; a double-glazed window with low-E coating on both panes might have an SHGC of about 0.35, meaning it transmits about half as much solar heat as the single clear pane. 

Air leakage, which is reported in cubic feet per minute per square foot of window (cfm/sq ft), is a measure of the movement of air (convection) between the inside and outside of a building through cracks in and around the window frame. Look for windows that have an air-leakage rating of 0.3 or less. 

The performance of windows on the U-factor and SHGC measures should appear on a label developed by the National Fenestration Rating Council (NFRC); a sample label appears in Figure 2. Don’t buy a window that lacks this label. Window manufacturers aren’t required to test their windows for, or display on the label, scores on air leakage. Testing and reporting on this measure is voluntary. 

Figure 2—Sample Label

Computer programs can help you estimate the energy cost consequences of different ratings on these performance measures. Some stores will have one of these programs to help you estimate the differences in energy costs that will result from selecting windows with different ratings—and also from adding new windows. You can also download for free a program called RESFEN from the Lawrence Berkeley National Laboratory website at

Figure 3 illustrates the energy-savings payback you might expect from installing better windows, which won’t offset the cost of the windows at today’s energy prices. Some features produce more energy savings than others, with the biggest savings generated by going from single- to double-pane glass. 

Figure 3—The Energy-Savings Payback from Better Windows

When deciding whether to invest in new windows, in addition to thinking about energy savings consider— 

  • How much you value the increased comfort and improved appearance the windows will provide 
  • How much the window improvements are likely to increase your home’s resale value 
  • How many years you expect to live in your house 
  • How much you could make (after taxes) if you instead put the money that windows would cost into a secure investment (such as a long-term bank CD) 

In terms of windows with additional energy-saving elements, consider not only the extra costs but also other issues. For example, the extra energy savings yielded by triple glass compared to double glass might require you to accept lower light transmittance, greater visual distortion, heavier and harder-to-move sashes, increased risk of breakdown of seals and the resulting condensation between panes (because there are two sets of seals rather than one), and less attractive grids (because grids placed between panes must generally fit into a smaller space in the triple-glazed windows). 

For more information on window-related energy savings and many other aspects of window purchases, check the Efficient Windows Collaborative website ( 

How Will They Affect Sunlight? 

You wouldn’t have much interest in windows you couldn’t see through and that didn’t admit light into your home. But not all windows are equal in this regard. “Visible transmittance” (VT), a measure of the amount of visible light that passes through a window, is affected by the window’s glazing material (glass or plastic), number of layers of panes, and any coatings applied to the panes. VT ranges from more than 90 percent for clear glass to less than 10 percent for windows with highly reflective coatings on tinted glass. NFRC labels report windows’ VT ratings. You may have to sacrifice some visible light that would come through a window to achieve an acceptable level of energy efficiency. This means that what you see outdoors will not look as bright as it otherwise would. The diminished brightness may not bother you—might even please you—on sunny days, but could be undesirable at night. 

Figure 4—U-Factor

Will They Last? 

Depending on construction, windows can last for decades—or rot and fail within a few years. Guarantees for the better-sealed window units run for 20 years or more and don’t prorate reductions in the covered value as time passes. 

You will have to judge for yourself the claims salespersons make about durability—no independent testing data on future durability of currently manufactured windows exists. By talking to various installers, you can get opinions on durability from companies that sell multiple brands, but this will provide a rough gauge at most. 

Major causes of window failure are weak corner joints in vinyl and wood-frame windows, and moisture (especially from condensation in wood windows). Ask for information relating to these hazards. In general, vinyl sashes that are welded rather than screwed together are stronger. To avoid moisture accumulation in wood window frames and sashes, buy windows with drainage holes and spaces for air circulation. 

With vinyl windows there is no required maintenance. Similarly, aluminum-covered areas of wooden windows require no maintenance. Exposed wood surfaces require painting, but the better manufacturers apply a thorough undercoating in the factory. 

Which Installer to Hire? 

Just as you need to be careful about selecting the right windows, you also need to be careful selecting an installer. We’ve received a disturbing number of complaints from consumers regarding window installation work. Even more alarming is that a large percentage of the complaints were about incredibly sloppy work. 

The ratings of local window installers on our Ratings Tables can help you avoid many of these problems. We surveyed area consumers (primarily CHECKBOOK and Consumer Reports subscribers) for their ratings of window installation outfits they had used. Our Ratings Tables show the results of our survey for the companies that received 10 or more ratings. The table reports the percent of each company’s surveyed customers who rated it “superior” (as opposed to “inferior” or “adequate”) for our survey questions “doing work properly,” “starting and completing work promptly,” “letting you know cost early,” “advice on service options and costs,” and “overall performance.” Our Ratings Tables also report the percent of surveyed customers who rated each company “adequate” or “superior” (as opposed to “inferior”) for “overall performance.” (For more information on our survey and other research methods, click here.) 

In addition to ratings from customers, for firms that were evaluated in our last full, published article, our Ratings Tables show counts of complaints we gathered from the Consumer Protection Division of the Washington Office of the Attorney General for a recent two-year period, and complaint rates relative to the volume of work companies do. For more information on reported complaint counts and rates, click here

How Much Will You Have to Pay? 

Cost can vary substantially depending on which windows you select and who installs them. 

Table 1 indicates the price variation between installation companies when we gave them exactly the same job specifications and let them decide which brand of windows to use. You can see that the highest priced company’s quote was often twice as high as the lowest quote. 

You can’t get the same brands of windows from all companies, but even among companies offering the same brand, company-to-company differences of $50 to $100 per window are common. 

Table 1 shows how surveyed companies compared on price when our shoppers got quotes for specified jobs. Our shoppers called the companies that were evaluated in our last full, published article and, without revealing their affiliation with CHECKBOOK, requested prices for three different jobs. The price comparison scores shown on our Ratings Tables (further described here) show how each company’s prices compared to the average price for all companies that quoted on the same jobs. We adjusted the price comparison scores so that the average for all the companies is $100. If a company’s score is $110, for example, this means that the company’s prices were, on average, 10 percent higher than the average prices we found for the same jobs. 

Table 1—Price Variation for the Same Specifications
Price Variation for the Same Specifications
JobLow priceAverage priceHigh price
Five double-hung replacement windows, 34 inches by 63.5 inches, insulated vinyl, fully fusion welded, double glazing, low-E coating, argon or krypton between panes$1,750$2,945$5,150
Eight double-hung replacement windows, 36 inches by 48 inches, insulated vinyl, cheapest assembly option, double glazing, cheapest air or gas fill, low-E coating$2,800$4,688$8,147
Six double-hung replacement windows, 36 inches by 72 inches, insulated vinyl, fully fusion welded, double glazing, grids of six panes over six panes for each window, argon fill, low-E coating$2,100$4,301$8,256

To get a good price we recommend the following steps— 

  • Have several installers come to your home, measure your windows, recommend a replacement method, recommend a brand and model of window, explain the reasons for their recommendations, and quote prices. 
  • Discuss these recommendations and ask about lower priced alternatives. If substantially lower prices would be available for less energy-efficient windows, ask the companies to estimate the actual energy savings the more expensive windows will produce. If you have no confidence in the scientific basis for these estimates, download the Lawrence Berkeley National Laboratory computer program mentioned above and ask for the National Fenestration Rating Council rating information for the recommended windows so you can make your own calculations. 
  • Based on the information collected, decide on your final specifications. Call the companies that already provided estimates and others to get their prices for these final specifications. Get a final quote from each company in writing. 
  • If you are not confident that the quality of the windows themselves is comparable from company to company when the companies simply quote on specifications, have the companies quote on a specific brand and model; several companies are likely to quote on some of the same brands and models. 
  • If you are remodeling and will be putting windows into roughed-in openings, consider having the contractor doing the other construction work purchase and install your windows, rather than dealing with a specialized window installation outfit. Window installation companies are primarily geared to installing replacement frames rather than new construction jobs. 

Check whether government programs or your utility company offers rebates or low-interest loans for installing energy-efficient windows. An excellent resource for incentives for all types of energy-efficiency solutions is, which maintains an up-to-date database of what’s currently available nationwide. 

What Should the Contract Say? 

Whichever window company you choose, make sure you have a tight contract. 

Details on the Product and the Installation Procedure 

What brand and model of window will be used in each opening? Will flashing be installed? Will it be painted? Will it match the existing trim? Will the windows meet Energy Star standards and qualify for the federal tax credit? Will there be an Energy Star label? Exactly how large will each opening be when prepared for the window, and how large will each window be—the glass and the opening? This last point is especially important because vagueness here means you risk having the company supply windows that are smaller than they should be—convenient for the company because the windows can easily be worked into place, but undesirable for you because the result might be packing out of the space before the new window is installed, less glass than you expected, and an ugly window. 


Contractors should carry two types of insurance—general liability and worker’s compensation—and be willing to show you a certificate that confirms the coverage. The first type insures against damages when a contractor drops a window; the second covers injuries to the worker it fell on. Homeowners policies may cover those incidents, too, but the contractor’s insurance should kick in first. 

Payment Schedule 

You should be able to pay all, or at least half, the contract price after the work is complete. The more you leave to the end, the more leverage you’ll have to make sure the work is done satisfactorily. 

Work Schedule 

The starting date should be firm so you can prepare for the job. A completion date is less important because most projects can be started within a week and take less than a day to complete. But it’s wise to add a phrase that the work will be continuous, and a note about who will be onsite supervising the job. 

Quality Promises 

To provide some recourse if the job proves to be obviously substandard, contracts should contain a phrase to the effect that the contractor will complete the project in a workmanlike and professional manner. 


Because window replacement projects generate a lot of construction debris, carting it away (and paying disposal fees) should be part of the contract. 

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