Editorial Feature

Vinyl Windows

Today, vinyl rivals traditional materials like wood in fenestration applications like windows and glass doors, providing comparable or better energy efficiency, aesthetics, design flexibility and cost criteria. In the following article, you'll learn more about how vinyl windows were developed and grew, as well as the performance, technical, environmental and design elements that have made vinyl a preferred material for many light commercial and residential window and glass door installations.

Overview

Vinyl windows and glass doors are used in many types of residential and light commercial construction, from schools, churches and office parks to apartment buildings, assisted living facilities and hotels. Vinyl windows and glass doors are constructed in much the same way as aluminium or wood windows, but with a chambered vinyl extrusion forming the frame around the glass, providing energy efficiency, durability and low maintenance. To ensure quality construction and window performance, many vinyl windows are certified by a third-party program and independent testing laboratory according to stringent industry standards.

Types of Window

Today, vinyl can be found in a number of fenestration products, including:

  • Single, double and triple hung windows
  • Sliding windows
  • Casement windows
  • Awning windows
  • Picture windows
  • Sliding door systems
  • French doors
  • Bay, bow and garden windows
  • Transom window
  • Skylights

Vinyl windows can also be found in such shapes as arches, ellipticals, eyebrows, gothic, trapezoids, rounds and half rounds, octagons, circles, ovals and half-ovals. Some window manufacturers also offer vinyl-clad windows, which are simply wood frames with a top layer of vinyl.

History

What was once just a functional necessity – a hole in the top of a cave designed to let out the heat and smoke from cooking and heating fires – is what we now call a window, and its purpose is both functional and aesthetic. The word "window" originates from the old Norse word, "vindauga," a combination of "vinder" (wind) and "auga" (eye). Therefore, a window is an "eye for the wind" or "wind-eye”.

After WWII

In the past, window frames were constructed of wood, aluminium or steel. But after World War II, facing a shortage of natural materials and a massive rebuilding challenge, Germany began producing extruded frames from vinyl, a relatively new thermoplastic. These early vinyl windows had a bulky, heavy-duty appearance that German consumers wanted, but were not accepted by American homeowners accustomed to narrow frames and larger viewing areas.

Improved Designs

However, in 1959, U.S. vinyl resin manufacturer BFGoodrich Company decided to give vinyl windows another try in the American marketplace by introducing products with sleeker lines and lower prices, and in styles that were patterned after traditional wood and metal windows. This was the beginning of today’s vinyl window industry in North America.

Since the 1980s, sales of vinyl windows have increasingly grown; in fact, from 1992 to 1998, the sales of vinyl windows in residential new construction and remodelling alone grew by nearly 125 percent. Today, most of the major wood window manufacturers offer vinyl windows as well, and vinyl rivals traditional materials for aesthetics, durability, energy efficiency and value.

Innovations in vinyl formulations continue to present new design flexibilities to architects and builders. A wood-vinyl composite that is made of sawdust and vinyl was recently introduced. This product can be embossed, has the appearance and feel of wood and can even be stained or painted. Another example is cellular foam vinyl that can be extruded into solid shapes for accessories to wood windows such as moulding and decorative trim. These cellular vinyl accessories can be nailed and painted at the job site, and will never rot or decay. These types of new product formulations will continue to pique the interest of designers and consumers alike.

Design Considerations

Product characteristics

Vinyl windows and glass doors offer many of the performance characteristics that specifiers rely on from windows made with traditional materials, with added benefits of low maintenance and durability. Vinyl windows and doors are impervious to rot, rust, corrosion, blistering, flaking and infestation by termites or other insects. Vinyl window and door profiles are typically white, grey, brown or tan, and the uniform colour is extruded throughout the product to ensure homogeneous colour and lasting colour retention. Colours can also be custom-made to meet the needs of individual projects, in which case the colour is co-extruded or layered in a thin coat onto the exterior surface. Vinyl windows are manufactured with ultraviolet (UV) inhibitors for improved weathering and stabilizers to protect the frames from cracking, splitting, pitting, peeling or chalking.

Design Options

Designers accustomed to using traditional window framing will find just as many, if not more, design options with vinyl. Nearly all shapes and styles of windows and glass doors are available with vinyl framing, and vinyl windows can also be customized to meet the size requirements of an individual project or design. Grids or panes for vinyl windows and doors range from standard to custom to enrich the appearance of an architectural or design theme.

Thermal Efficiency

Vinyl windows and glass doors perform extremely well in comparison to alternative framing materials in energy and thermal efficiency ratings. Energy-efficient windows mean lower heating and cooling costs for a home or building owner, as well as environmental benefits. Vinyl as a material is not a conductor of heat and cold, and hollow chambers within the frame provide thermal barriers that further block heat transfer.

Technical Data

All windows and glass doors must meet minimum requirements for design pressure (windload), structural test pressure (structural load) and water resistance test pressure according to industry standards. The type of building, elevation, wind zone, exposure, terrain and proximity to the coastline, as well as local code requirements, determine the window performance parameters. In general, vinyl windows and glass doors meet the minimum test requirements for residential and light commercial use.

Vinyl windows and glass doors are not suitable for some applications such as high-rise office buildings with severe windload resistance requirements. However, vinyl windows and glass doors can be used in most commercial settings, such as industrial buildings, factories, hotels, retail stores, hospitals, schools and other buildings.

Installation

Regardless of the framing material, proper installation is absolutely critical to the optimum performance of a window. Windows that are improperly installed will be less energy efficient and will not provide the quality performance life for which they’re designed. Some of the possible installation mistakes on vinyl windows and doors include creating openings that are too large, improper flashing, improper choice of anchorage or too much space between fasteners. These mistakes can be found in the installation of all types of windows.

Cost

The installed costs and lifecycle costs of vinyl windows and glass doors are competitive with those of other framing materials, and in most cases vinyl is the most affordable alternative.

Maintenance Requirements

Very little maintenance is required with vinyl windows and glass doors. They may require a periodic cleaning with a standard household cleaner but will never need to be painted, stained or otherwise treated to maintain their colour and strength. Some vinyl window and glass door products allow for painting on the exterior or staining on the interior, and special paints are available for this purpose. The average lifespan of vinyl windows and glass doors varies widely according to the intended application and other factors, but most vinyl window manufacturers offer warranties of 20 to 30 years.

Selection and Specification Guide

Relevant standards

The most significant standard by which the performance of vinyl window and door frames should be judged is AAMA/NWWDA 101/I.S.2-97, "Voluntary Specifications for Aluminium, Vinyl and Wood Windows and Glass Doors." This unified standard specifies the minimum performance requirements for windows, regardless of framing material. In order to become certified by the American Architectural Manufacturers Association (AAMA), all windows must meet this minimum standard during testing by an independent third-party laboratory. Certified products meet testing standards for structural adequacy to withstand wind loads, resistance to water leakage, air infiltration, forced entry and other non-mandatory performance requirements.

Code Information

Vinyl windows are widely accepted for use in light commercial (low-rise) and residential buildings by model building codes across the USA.

Manufacturing

Raw materials

All vinyl products are made from combinations of vinyl resin and various additives which give these products their particular properties. Every formulation is different, and most are proprietary. Most vinyl window formulations are made up of about 80 percent vinyl resin. Some of the additives commonly used in vinyl window and door profiles include:

  • Stabilizers, which help minimize the degradation of the vinyl during exposures to high temperatures in the extrusion process. They also help prevent cracking, splitting, pitting, peeling or chalking.
  • Pigments to provide consistent colour throughout the product and to screen or absorb UV radiation, which would otherwise cause rapid degradation of the product.
  • Modifiers to provide impact properties, or resistance to cracking or breaking during the fabrication processes, including sawing, routing and punching. These additives also improve resistance to general abuse during transportation, storage and installation

Processing / Fabricating

Once the additives have been combined with the resin, the resulting material is called vinyl compound. The vinyl additives are mixed evenly throughout vinyl compounds, which ensures consistency of colour, strength and UV resistance. Once compounded, these additives are chemically combined or locked into the structure of the profile material, minimizing any loss of properties or discoloration. The compound is then softened or melted, mixed and forced through a uniquely shaped opening or die in a process called extrusion.

These extrusions, which form the basis for a vinyl window assembly, are shipped to a window fabricator on pallets. The window fabricator then cuts the bulk lengths to the specified dimensions of the window. Machines cut the profiles to accept the appropriate hardware and prepare the components for assembly. The frame and sash components are most often fusion-welded together to form air- and water-tight corners. The remainder of the assembly entails installation of locks, keepers, balances, operators, weather stripping and insulated glass.

Environmental Considerations

Recyclability

Like all vinyl products, vinyl window and glass door profiles are recyclable, both pre-use (e.g., manufacturing off-cuttings and construction site waste) and post-use (e.g., removal at end of useful life). Because vinyl is a thermoplastic, it can be reprocessed for recycling using heat with minimal loss of properties. In the fenestration industry in particular, several major vinyl window extruders not only recycle their own in-house scrap, but they also accept – and in some cases, buy back – scrap from window fabricators to recycle back into new vinyl windows and doors. Vinyl window scrap is also highly valued for use in other rigid vinyl applications like PVC pipe. If recycling is not an option, and vinyl window and door scrap must be landfilled, it can be trusted to remain safely inert under normal landfill conditions. At the same time, vinyl’s inherent durability means these products will serve long useful lives, preventing waste from being generated when less durable products are used.

Energy Efficiency

Vinyl windows and doors are energy efficient during both the manufacturing and use phases of their lifecycle.

Manufacturing Phase

Vinyl products in general have low embodied energy, which means that the amount of energy required to convert raw material into a final product is lower than for many alternatives. In fact, a lifecycle study by Franklin Associates has shown that vinyl windows require three times less energy to manufacture than aluminium windows. The use of vinyl over alternatives in window frames saves the United States nearly 2 trillion BTUs of energy per year – enough to meet the yearly electrical needs of 20,000 single-family homes.

Use Phase

Vinyl windows and doors continue to save energy throughout their useful lives. Vinyl is an efficient insulating material for heat and cold, which means that the windows maintain an even temperature, keeping them comfortable to the touch and decreasing condensation caused by indoor/outdoor temperature and humidity differentials. The design of vinyl window frames further enhances their energy efficiency by creating chambers in the frame that provide additional resistance to heat transfer and insulating air pockets. The frames and sash corners are fusion-welded for maximum strength and protection against air and water infiltration.

Air Quality

The energy efficiency of vinyl windows and glass doors means less electricity must be used to heat and cool a home or building, reducing the greenhouse gas emissions associated with coal-fired power plants. In addition, the low maintenance requirements of vinyl windows and glass doors eliminates the need for paints, stains, strippers and thinners, which can negatively impact indoor air quality.

Source: The Vinyl Institute

For more information on this source please visit The Vinyl Institute

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