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NAICS: 32-1911 Wood Windows and Doors, 32-6199 Plastics Product Manufacturing, not elsewhere classified, 32-7211 Flat Glass Manufacturing, 33-2321 Metal Window and Door Manufacturing

SIC: 2431 Millwork, 3089 Plastics Products, not elsewhere classified, 3442 Metal Door, Sash, and Trim

NAICS-Based Product Codes: 32-19111, 32-19115, 32-1911W, 32-61998131, 33-23213, 33-23217, 33-23219, and 33-2321W


People think of windows as openings in walls, but in a stricter sense windows are special kinds of closures in walls that let light in and let us look out and, when opened, can air an area. The origin of the word in Old Norse combined these senses. Vindauga meant wind eye. Several other languages originating in Europe use a word based on wind when signifying window. Thus the Danish word is vindue and the Norwegian vindu. The Spanish for window is ventana, a word that comes from the Latin for wind, ventus. Other languages derive from the Latin for wind, fenestra; that word developed from the concept of a hole or opening. The Dutch say venster, the Germans fenster, the Swedes fönster, the Italians finestra, the French fenênetre. The Dutch also use the word raam which derives from frame or enclosure.

In the creation of residential or other structures builders frame buildings leaving appropriately located openings for windows. In modern practice windows are produced in factories and shipped to building sites in finished and ready-to-install units. In certain types of construction, particularly in high rise office buildings, the window takes the form of walls, not single units. The builder hangs specially fabricated curtain walls of glass from the building's metal frame. In residential applications windows come as units, usually in standard sizes. The builder orders special windows separately. A substantial portion of industry shipments are replacement windows purchased by homeowners. Windows are replaced for many reasons. The most important of these is energy conservation. People replace their windows because they want to save money and improve the appearance of their house. Replacing windows can reduce maintenance costs, provide better interior lighting, and change the entire appearance of a repainted house.

Sash, Frame, and More

Although windows appear to be quite simple products they are actually complex structures. Many an individual setting out to repair an old window put in place in the 1930s or 1940s has discovered the complexity in layers of disassembly and has gained respect for the producers of modern windows.

The core element of a window is the sash, the frame that actually holds the glass. The sash may hold a single piece of glass or may be subdivided into multiple panes separated by grilles or so-called mutin bars. All sashes have a locking mechanism and either sliding rails or hinges depending on how they are to be opened. Fixed windows that cannot be opened are the exception. Movable sashes come in six varieties and windows are named after them: casement, single-hung, double-hung, sliders, awnings, and hoppers.

  • Casement Windows. The sash is hinged at one side and opens outward. The sash may be moved by hand or may be activated by lever cranked by the user. When the sash is closed, one or more locks may be supplied to close it firmly.
  • Single- or Double-Hung Windows. Such windows have two sashes arranged one above the other. In a single-hung window the upper is sash stationary whereas the lower can be opened, overlapping the upper sash. In the double-hung version, both sashes may be opened, the lower being raised, the upper being lowered. In old-fashioned designs the movement of the sashes was aided by weights (called balances) suspended on ropes running over a pulley, the entire arrangement hidden beneath the frame to either side. Modern windows use springs or compressible weather-stripping to keep the windows stationary.
  • Sliders. These window work in a manner analogous to hung windows but may be opened by sliding them from side to side.
  • Awnings Windows. The sash in this type of a window is hinged at or near the top and is intended to be opened outward. Levers hold the window open. Awnings are frequently crank-operated.
  • Hoppers. The sash is hinged near or at the bottom and opens inward. Many single- and double-hung window sashes are also equipped with hinging at the bottom so that they may be opened inward for cleaning or outright removal. Hoppers, however, are designed for opening in that manner and no other.

Fixed windows, the seventh type, are often used for decorative purposes. They may feature stained glass or be of unusual shape (arched, triangular, hexagonal, etc.), making them difficult to implement for opening except at unusually high cost.

Groupings of windows have special names. Bay windows form semi-circles. Transoms are windows set above doors, sidelights to either side of doors, and fanlights are arched windows above doors to throw light into an entry-way.

Sashes are also defined by the number of panes that they carry separated by mutin bars. If the sash carries more than one pane, the terminology used is upper over lower—each word applying to half the sash. Thus a 1/1 window has two panes, one over the other. A common type is 6/6, with six small panes on the upper level, six on the bottom. Other common types are 2/2, 4/4, and 9/6. Glass doors, and sometimes windows as well, feature 3/1 or 4/1, instances in which the upper half is subdivided into three or four narrow panes and a single large one forms the bottom. In some designs a window that appears to have multiple panes actually features but a single sheet of glass with mutin bars made of wood or plastic overlaid to give the appearance of multiple panes. In double-glazed windows fake and very thin mutin bars may be embedded between the panes of glass. The window looks subdivided, but in washing it the user can wipe over a single pane of glass.

The glass used in sashes may also be complexly produced in double or triple-glazed panes. In the double-glazed window, two sheets of glass are joined by a spacer at the edges, the spacer sealed in with plastic backed by a silicone seal to prevent loss of heat. A layer of air between the panes provides insulation as well. More sophisticated versions of double- and triple-glazing substitute argon gas for the air between two or more layers. The third layer may be a thin sheet of translucent plastic. The object of double- or triple-glazing is to reduce heat loss from the interior. The insulating power of a material is typically measured by R-Value. The letter stands for resistance to heat loss. A six-inch layer of fiberglass has an R-Value of 19, a single pane of glass a value of 1.04. Glass is thus a poor insulator. Double-glazed glass panes will have an R-Value of 2 and triple-glazed panes an R-Value of almost 7. With large areas of a room open to the outdoors, increasing the R-Value translates, over time, into real energy savings. In the windows industry customers may encounter references to the U-Factor, another form of the R-Value. It is derived by dividing the R-Value into 1. The higher the R-Value, the lower the U-Value. The U-Factor is apparently used by the industry for marketing purposes. The better the insulation the lower the U-Factor will be—thus it is easier to explain low heat loss by low numbers rather than by high R-Values. Math can be used to improve the sales message.

Glass used in windows may also be specially coated with metallic oxides to produce so-called low-e glass. The e stands for emittance. The coatings limit radiation gain from the sun or heat loss from within. The invisible portions of sunlight, in the infrared segment of light, penetrate glass but only introduce heat. Ultraviolet light is also invisible but can cause materials to fade in color. Metal oxide coatings, applied in microscopic quantities and thus invisible to the naked eye, act to reflect back at least a part of the invisible spectrum in the summer months while letting visible light in. Low-e windows are coated on both sides. The inner coating, like the outer, reflects back energy reaching the window as invisible rays and keeping the house warm in the winter. Low-e coatings applied to the outer surface must be applied during the glass-making process itself which makes the glass more expensive. The interior coating may be applied later but is less durable so it is never used on outside surfaces. Special coatings are also applied to high-end windows to cause rainwater to run off rather than to dry in place, thus reducing user maintenance activity.

The sash itself fits into the window frame. The frame is a basic rectangle with a head on top, a sill on the bottom, and jambs on either side. Centered around this rectangle but on its outer perimeter is a nailing flange. The installer uses it to affix the frame to structural beams left by the builder to mark out the window hole and to provide support for the window. The top of this rough framing is the header, its bottom is called the rough sill. The interior portions of the frame are equipped with rails to accommodate sliding windows or they hold hinges to allow the sash to move inward or out. Where mechanisms like springs or weights are needed, the frame will be more complicated in order to provide room for such devices. Most windows, or portions of them, are protected from insects by a screen when the sash is opened. Mounting for screens are affixed to the frame as well, inside or out, depending on the type of window. Screens may be permanently affixed, move in rails of their own, and may be removable. The structural framing, that which does real work, is finished inside and out with a decorative casing. When we look at a window, that is what we see—the casing and the sash. The head-casing at the top may extend on from the house to serve as a drip cap for catching rain drops; attached to the sill at the bottom may be a decorative piece known as the apron.

Wood, Metal, and Plastic

The material forming the frame and sash of windows plays a major part in differentiating products in this market. The oldest, traditional, and still universally considered as the best material for holding glass is wood. As a natural material it has superior appearance, high R-Values, and filters out noise effectively. Wood windows, however, are subject to environmental effects, will rot unless protected by paint, generally require more maintenance, and are the most expensive window material on the market.

Steel-framed windows were commonly installed early in the twentieth century in residential as well as in commercial buildings. Such window had the advantage of great strength but had very unattractive R-Values. For energy conservation, homeowners had to install fixed storm windows that stayed shut all winter—and had to remove them again in spring. At the time these early windows were put in place people did not worry about energy inefficiency. They did concern themselves with costs, but storm windows saved fuel. Aluminum appeared as the next dominant material for metal framing. The metal continues to be important in the twenty-first century as well in commercial applications. Commercial builders value the strength of aluminum as it enables them to offer large glass surfaces with low noise penetration from the outdoors. The cost of aluminum windows is the lowest, also making it an economical choice for commercial builders. Aluminum windows, however, have the worst R-Values despite insulating spacers used in their installation. In the commercial market aluminum continues to be dominant, but in the replacement market, where aluminum once reigned supreme because of its low cost, it is now a very small factor. Aluminum windows are almost never used in new residential construction.

Although polycarbonate, polyethylene, polyurethane, and polystyrene are used by some producers, the two most important plastics in use in the first decade of the twenty-first century are polyvinyl chloride (PVC), the vinyl window in industry parlance, and acrylic, at a distance, the fiberglass window in trade terminology. Vinyl windows are the most purchased category in the residential replacement market. They are inexpensive, have much better insulation characteristics than aluminum, and are maintenance-free. Fiberglass windows are stronger than vinyl or wood, available in dark colors (whereas vinyl is available in lighter colors only), and comparable to vinyl in insulation value. Fiberglass windows, however, are expensive, costing only slightly less than wood, and thus have the lowest share of the market.


Industry Structure

As viewed by the U.S. Census Bureau, windows and doors are handled together in single industries for the obvious reason that producers of windows tend also to offer doors. This is a somewhat fuzzy generalization. Many firms specialize—producing only doors, or garage doors, or windows of a particular type—and this is especially true in the commercial sector. Nevertheless, the Census Bureau reports data separately on the Wood Windows and Doors and on the Metal Windows and Doors industries. It reports the production of plastic windows and doors as a subcomponent of Plastic Products Manufacturing not elsewhere classified, thus plastic windows fall into the Bureau's miscellaneous plastics categorization. All producers of windows obtain their glass from the Flat Glass Manufacturing industry. About 75 percent of this industry's output ends up in windows, the rest in a multiplicity of applications of which automobiles are the largest.

The statistical view of the industry is also blurred by budget cutbacks that have affected the Census Bureau's reporting. Thus details on the wood and metal windows industries are available only in years for which detailed data are collected, census years which end in 2 and 7, the data for which are collected the year after. At the time of writing data for 2002 were the most recent available data detailed enough to identify windows industries and product categories within them. In all other years the Census Bureau has combined wood windows into a collective industry called Millwork and metal windows into another one called Ornamental, Sheet, and Architectural Metal Work Manufacturing. Plastics are already submerged with other categories. Market estimates presented rely on intelligent guesswork for the years beyond 2002 based on trend projections and spottily available industrial market research.

The products of these industries reach three quite distinct markets: commercial construction, residential new construction, and the window replacement market. The commercial market is in part residential or temporarily residential construction in the form of multi-family housing units, apartment houses, hotels, hospitals, and similar structures.

Producers in the industry tend to be in one or another major materials category. They are manufacturers of wood, vinyl or other plastic, or aluminum windows.

Estimates of the Market

In 2005 at the production level, window shipments were a $13.7 billion market in the United States, up from a level of $11.3 billion in 1997, growing at an annual rate of 4.1 percent. The growth rate of windows in the 1997–2005 period exactly matched the growth rates of housing completed, suggesting a strong correlation between window sales and new residential construction. In 1997, according to the Census Bureau, 1.4 million housing units were finished, in 2005 1.9 million units. Windows are usually one of the last items installed in new homes making the completion of new homes a good measure for correlating housing to actual window sales. The industry itself, however, prefers to track housing starts, a statistical measure providing a rough forecast of future orders. Housing starts grew at a slightly higher rate of 4.3 percent a year in this period.

The correlation between window shipments and number of houses completed is somewhat artificial, because dollars of shipments are matched with units of housing completed. In Figure 230 another correlation is presented, that which exists between shipments of windows in dollars and new construction (private residential and nonresidential) put in place, also in dollars.

Construction put in place was growing at 7.8 percent for all private construction combined, much faster than shipments of windows. Residential construction put in place grew at 10.7 percent per year, non-residential construction at the rate of 2.7 percent. Figure 230 clearly shows that windows correlate better with residential construction but have been growing at a lower rate in dollars, in part explained by the fact that plastic windows, representing the low end of windows installed in residences, have been growing much faster than pricey wood windows (at 6.6% per year versus wood's 2.4% per year). Metal windows, used almost exclusively in commercial and public construction, grew at 3.5 percent yearly. Data on the public construction segment, which represents 24 percent of all construction put in place, could not be analyzed over time because changes in definitions had been introduced, old series of data interrupted, and the Census Bureau only reported on two years of activity. Public construction, however, which includes public office buildings and schools, accounted for an indeterminable but likely a sizeable segment of metal window purchases.

Shifts in materials for the same period are shown for the 1997–2005 period in Figure 231. In this period, as measured in dollars, plastics had become the top-ranked window material in 2005. Vinyl windows dominate the window replacement market. Based on data from the Census Bureau, which separately tracks expenditures on residential improvements and repairs, windows used in this general category represented $5.7 billion in expenditures in 2005. This would suggest that around 36 percent of all windows made end up replacing other windows. Of that total nearly two thirds are vinyl, just shy of three in ten are wood, and the rest are aluminum and expensive fiberglass windows.


The industry producing windows somewhat mirrors the construction industry in having many producers. This is a fragmented rather than a consolidated industry. Its largest companies have a relatively small share of the market.

In the wood segment of the industry 1,326 companies participated in 2002. Their numbers had increased by 15 from a 1997 base of 1,311 participants—bucking the trend of shrinking numbers in most U.S. industries. In 2002 participating companies operated 1,440 establishments, with just a few having multiple sites. In the metal segment 1,156 companies participated in the business in 2002 and operated 1,321 establishments. In the 1997–2002 period 93 companies disappeared by going out of business or being acquired; in that same period 89 establishments ceased to operate. This pattern in metal undoubtedly reflected the competitive pressures from plastic windows in the residential market. Similar data for plastic windows were not available. Census Bureau data on company participation and establishment counts are provided only for a great miscellany of plastic products merged together, including plumbing fixtures, floor coverings, automotive plastics, electrical plastics, building and construction plastics (our subdivision), shoes, furniture, and more. The pattern observed in wood windows, however, probably applies to plastic windows as well., for instance, the Web site of Thomas Register, a publisher of manufacturers' directories, lists 572 suppliers in the industry, likely to be a subset of total participants. Some overlap between companies also exists because large companies in the wood window industry also sell vinyl and/or aluminum windows.

The leading companies in windows and doors—the two categories are always combined within the industry itself and in corporate classifications as well—are Andersen, Atrium, Jeld-Wen, and Pella. As a group these companies are thought to hold a 20 percent share of the windows and doors market. Definitive rankings are made difficult, however, because the leaders in this industry, as well as most of the participants, are privately held corporations that do not publish financial reports available to the public.

Andersen Corporation

Headquartered in Bayport, Minnesota, this company was the leading producer of wood windows in the United States in 2005 and, through acquisitions, also a participant in vinyl and aluminum products. In that year, as estimated by Forbes in its listing of top privately-held companies, Andersen had sales of $3.0 billion. The company was founded by Hans Andersen, a Danish immigrant, in 1903. The company's main manufacturing operation is in Bayport, but Andersen also operates a number of subsidiaries including Renewal by Andersen (replacements), EMCO Doors (seasonal and storm doors), KML Windows (architectural windows and entrances), Silver Line Building Products (a leading supplier of vinyl windows and doors with multiple production sites), Eagle Window and Door (aluminum clad windows and doors), and Dashwood Industries (Canadian producer of roof windows and skylights). Andersen operates its own research organization and also maintains fifteen distribution centers across the country and in Canada; Dashwood operating as Andersen's Canadian logistical arm. Andersen employs around 8,500 people.

Jeld-Wen, Inc.

This company sells wood and clad-wood, vinyl, and aluminum windows; clad-wood windows are wood windows with an outer sheathing of vinyl for protection against the weather. Jeld-Wen began as a small millwork operation in Klamath Falls, Oregon, in 1980 and grew in part by acquisition. In 2003 the company had twenty-seven different brands of windows and doors and made the decision that year to sell them all under the Jeld-Wen brand name. Hoover's, Inc., the financial publisher, estimated Jeld-Wen's sales in 2005 at $2.6 billion. The company's name is not often put on lists of multinationals, but Jeld-Wen operates in Canada, the United States, in South America, Europe, Thailand, Malaysia, Indonesia, Korea, and Australia. The company has 150 divisions and employs 20,000 people.

Pella Corporation

Pella was founded in 1925 by Pete and Lucille Kuyper in Des Moines, Iowa, to exploit the invention of what the founders called the Rolscreen®, a screen that rolled out of sight when not in use. The enterprise was called Rolscreen Company until the Kuypers moved the business back to their hometown, Pella, Iowa. Pella still offers its patented but technically updated Rolscreen in its modern windows. With sales in 2005 of $1.3 billion as estimated by Hoover's, Pella manufactures wood, vinyl, and fiberglass windows at twelve locations in the United States; five in Iowa and others in Arizona, Illinois, Kentucky, Ohio, Oregon, Pennsylvania, and in South Carolina. The company employs 8,300 people.

Atrium Windows and Doors

This company is thought to be the leading producer of vinyl and aluminum windows in North America. Based in Dallas, Texas, Atrium Windows and Doors began operations in 1948, initially only in the Southwest. In 2006 the company had estimated sales of around $910 million, the sales estimated based on its employment of more than 7,000 people. Atrium operates 10 manufacturing and 12 component production facilities and distributes products through forty branches in the United States. Atrium also operates in Canada and Mexico.

The most important component of windows is glass, particularly a category called flat glass. The leading glass producer in the United States is PPG Industries, Inc. Although PPG abbreviates its name in modern style, the letters once stood for Pittsburgh Plate Glass. PPG had sales in 2006 of $11 billion of which $2.2 billion were accounted for by its glass segment; PPG employed 8,900 people in its glass operations.


The industry is present in every state, with leading states in number of establishments being California (208), Texas (94), New York (67), and Florida (67), suggesting producer concentrations in regions of large populations. States with the most employment are Wisconsin (10,100), Minnesota (8,400), and Iowa (7,800). Wisconsin is the home of several window manufacturers including Heritage, Kolbe & Kolbe, Monarch, Semling-Menke, and some operations of Jeld-Wen; Minnesota is Andersen's location, and Iowa is Pella's.

Flat glass can be obtained at various locations around the country including California, Washington, Texas, Illinois, Michigan, Georgia, South Carolina, and in Ontario, Canada—this list obtained by looking only at the production facilities of PPG and the French company, Saint Gobain, which operates four flat glass plants in the United States. Saint Gobain also owns CertainTeed Corp., another leading window producer. All told, some 63 establishments supply glass.

Wood products and plastics are similarly widely available across the country so that materials supply does not significantly affect the industry. The concentration of establishments, however, suggests that producers like to locate close to centers of construction activity. Andersen, located almost on the border with Canada in northern Minnesota is an exception.


The distribution system in this industry may be very simple or it may follow a complicated channel. The simplest distribution is directly from the manufacturer, typically a small enterprise operating in a local market, to the homeowner. The producing company sells its own production directly and uses its own employees to install the product. In the more complex distribution systems, product moves from the manufacturer to a manufacturer's branch, from the branch to a millwork wholesaler, from the millwork wholesaler to another distributor, typically a lumberyard, and from the lumberyard to the builder. The ultimate customer buys the windows indirectly when purchasing a new house.

Variations are common in new constructions. Distribution of replacement windows, which typically require more special fitting of windows to non-standard openings, usually involve specialized dealers as well.

Lumberyards, for instance, typically obtain only a portion of their product from a millwork wholesaler and they buy the rest directly from the manufacturer, especially if the manufacturer maintains a branch structure to service local lumberyards—branch operations are common among larger manufacturers of windows and doors. The industry also features a type of wholesaler common in the construction trade. These organizations, called wholesale retailers buy approximately 60 percent of their product directly from manufacturers and supplement their supplies from millwork wholesalers. They sell to builders. Specialty retailers specialize in windows and doors. They buy almost exclusively from manufacturers, bypassing the one- or two-tier wholesale distribution channel, and sell their product either to new construction or to the homeowner, supplying installation as a service. Finally, so-called Big Box stores, such as Home Depot and Lowe's, deal directly with manufacturers to obtain around 85 percent of their product and sell these principally to remodeling contractors.


Key users of windows are, quite simply, two groups: builders of new residential and commercial structures and homeowners wishing to update their residence with replacement windows.


Markets directly related to windows include textiles used to produce curtains and draperies and products for shading windows against glare or to protect privacy. The largest of these products are awnings mounted permanently to the outside of windows. External jalousies serve a similar purpose. Window shades used inside come in a great variety made of textiles, treated paper, plastics, wood, and coated metals. Window cleaning services are a recognizable and well-organized aspect of commercial window maintenance. These services have their counterparts in window-cleaning chemicals in the household.

Producers of windows almost always produce doors as well. The predominant material used in doors is steel, but many front doors have decorative inset windows or come with a transom above or sidelights to either side. Doors leading outward to patios are frequently glass doors and, in functionality, are simply very large windows one can slide open to exit or enter. In the wood industry, windows are the dominant product as measured in dollars, in the metal industry doors dominate total production.


The predominant motive for R&D in the windows industry is provided by energy conservation, which provides user motivation for upgrades. Energy-efficient windows are typically top-of-the-line products with the richest margins offering manufacturers the greatest returns.

Concerned as it is with energy, the U.S. Department of Energy (DEO) has taken a lead role in encouraging and coordinating research within the windows industry and within others supplying it, such as glass and coatings producers. The major thrusts of research identified by DOE are:

  1. Heat loss prevention, conserving energy within the structure
  2. Selective managing of heat gain through the window, conserving energy used in air-conditioning
  3. Better utilization of light reaching from outdoors in, thus reducing electrical energy use for lighting
  4. Manufacturing methods that use less energy.

Approaches to achieving the best results in all four areas involve multi-faceted approaches, among them improved glass coatings such as translucent insulating gels, alternative glazing materials, detectors able to identify the loss of insulating gasses in double- and triple-glazed windows, architectural coatings for window frames (paints with insulating capacities), and even using holograms to concentrate light outside to designated spaces within. DOE and its industrial partners are also seeking to educate the public about the cost-effectiveness of more expensive windows with higher insulating values, code changes to stimulate such upgrading, and manufacturing methods to reduce energy use in, for instance, producing aluminum extrusions.


The market for windows is largely a consequence of trends in construction. For this reason associations in the industry carefully track housing starts and other indicators that impinge on building activity, including mortgage interest rates. In that purchasing replacement windows also usually involves substantial expenditures, both interest rates and consumer confidence influence this segment of the market as they do with construction generally.

In the early 2000s overeager lenders began approving mortgages to barely-qualified borrowers. In time they produced a crisis in residential construction, banking, and on Wall Street, usually referred to as the subprime lending fiasco. The term subprime derives from the concept of a prime lender who issues mortgages only to well-qualified borrowers. Subprime lenders engage in lending to a public below those qualified to borrow at regular market rates. In the first decade of the twenty-first century some mainstream lenders began participating more actively in subprime lending at the margins of their activities, thus through subsidiaries. Mounting default rates brought this situation into the open and unnerved the investment community. That community feared that bankruptcies in the sector would affect the entire financial sector and further deflate what was an already weak housing market. Precisely how this phenomenon would work itself out through the economy was not entirely evident at the time of writing. Such phenomena, however, affect the demand for windows.

Another important trend in the middle of the first decade of the twenty-first century was the incremental gain of vinyl as a major window material and the near-disappearance of aluminum windows in residential construction. Major companies in the wood window sector were responding to this trend by acquiring lines of vinyl windows quietly; quietly because they wished to participate in the growing sector without implying that their main product was in any way deficient.


The principal marketing strategies employed in the industry tend to depend on the type of windows being marketed—wood, metal, vinyl, or fiberglass. Wood windows represent the high-end of the market and are sold for their superior appearance, natural look and feel, and very good R-Values. Metal windows are preferred by architects, builders, and users in commercial construction because they deliver large window surfaces at the least cost. Vinyl windows are the low-end of the market and are purchased to achieve functional replacement of deteriorating windows, often framed in steel, at the least cost. In selling fiberglass windows, producers emphasize superior strength and the low maintenance aspects of the product as well as the broad choice of colors available.


American Architectural Manufacturers Association, (AAMA),

National Fenestration Rating Council,

Window & Door Manufacturers Association (WDMA),


Darnay, Arsen J. and Joyce P. Simkin. Manufacturing & Distribution USA, 4th ed. Thomson Gale, 2006, Volume 1, 333-341.

"Determining the R-Value You Need for an Existing House." Insulation Fact Sheet. U.S. Department of Energy. 19 January 2004.

Lazich, Robert S. Market Share Reporter 2007. Thomson Gale, 2006, Volume 1, 8-9.

"New Residential Construction." U.S. Department of Commerce, Bureau of the Census. Available from 〈〉.

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Saxler, Robert J. "Renovation, Remodeling, and Window Replacement: Renewed Life for Vintage Architecture." Architectural Record. Available from 〈〉.

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see also Blinds & Shades