Guide to Selecting & Installing, Solid Vinyl Windows
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Solid vinyl window properties
Vinyl window choices, installation, maintenance
Wood, vinyl-clad, solid vinyl, fiberglass, aluminum composite window & door properties
Window certifications & standards for vinyl windows
Questions & answers about vinyl & vinyl clad windows

Solid vinyl windows, guide: this article explains the properties of solid vinyl windows, vinyl window choices, and how to install and maintain vinyl windows.

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Windows, Vinyl Guide

In this article series we discuss the selection and installation of solid vinyl windows and doors, following best construction and design practices for building lighting and ventilation, with attention to the impact on building heating and cooling costs, indoor air quality, and comfort of occupants. We review the proper installation details for windows and doors, and we compare the durability of different window and door materials and types. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

Also see VINYL / PVC WINDOW WARPING, and see WINDOWS & DOORS our home page for window and door information, and also see WINDOW TYPES - Photo Guide for a photographic guide to window and door types and architectural styles. Our links at page left provide in-depth articles on window and door selection, inspection, installation, problem diagnosis, and repair.

Solid vinyl windows can attribute their surge in popularity over the past decade to the fact that they have delivered a high-quality, maintenance-free product for about a third less cost than a clad window of comparable quality.

Contractors like the fact that the interior window sashes do not need painting, and homeowners like the notion that the frame and sill cannot rot (although vinyl windows do not live forever).

Solid vinyl windows have shed their image as cheap plastic replacement windows by continually improving to the point where premium quality vinyl windows are stronger and more dimensionally stable, more fade resistant, and better looking with crisper extrusions and better hardware (Figure 3-4).

As an added benefit, vinyl window manufacturers claim that their products can match the energy performance of wood windows.

While improvements in extrusions have made vinyl windows less bulky looking, they still do not have the crisp lines of a wood window, particularly on the interior, and vinyl window sash are unmistakably white plastic.

Still, vinyl windows have shed their stigma as a low-end product and are finding their way into more and more new homes across the spectrum from spec to upper-end custom.

Construction of Solid Vinyl Windows

Vinyl window quality starts with the chemistry.

\A number of additives are blended into the raw vinyl to make it more dimensionally stable and more resistant to UV radiation, which otherwise can cause the vinyl to fade, chalk, and become brittle over time.

The vinyl is then extruded into long sections with multiple internal chambers that give the material its rigidity and insulation value from the trapped air (see Figure 3-5 at left).

The thin-walled plastic ranges in thickness from about .065 to .085 inch. All other things being equal, the thicker the plastic, the stronger the window component. However, extrusions can gain strength from having a well-engineered profile, as well (many European windows use much heavier .125-inch plastic, but U.S. manufacturers feel this would make them less competitive).

The extrusions are then cut and joined to create frames and sash. Nowadays, most corners are heat-welded, producing the strongest joints, although some corners are still mechanically fastened. Some manufacturers add steel or aluminum reinforcing, particularly to larger windows, to stiffen them and help them meet structural load requirements. Typical places for reinforcing are sills, which have a tendency to sag in hot weather, lock rails, and mullions between mulled units.

Vinyl Window Options

All vinyl windows have an integral nailing flange, simplifying watertight installations (see Window Flashing & Sealing Guide).

All standard window types, including tilt-turn, are available in solid vinyl today. All glazing types, except for true divided lites, are also available. For the look of divided lites, the options are either snap-in grilles or between-the-glass grills.

Typical exterior trims include brickmold or nominal 4-inch flat casings with either an integral or snap-on J-channel to receive the ends of wood, vinyl, or fiber cement siding.

Window trims designed for stucco are widely available in the western states and Florida. Colors are generally limited to white and beige, since dark colors absorb heat and raise vinyl temperatures to near 165°F, where it begins to soften and sag. On the interior, most vinyl windows will accept either wood extension jambs or drywall returns.

Quality Issues with Vinyl Windows

As with any building products, not all vinyl windows are created equal. Many early models were poorly made and subject to excessive thermal movement, often opening at corners, fading prematurely, and losing structural integrity from UV exposure, particularly in hot climates.

Warping was a complaint for some PVC vinyl windows, as we discuss at VINYL / PVC WINDOW WARPING.

Most window manufacturers today have overcome these problems with better vinyl formulations, improved extrusion design, and heat welding at corners. Many also use metal reinforcing at strategic points, such as meeting rails, sills of large units, and between mulled units.

Since the chemistry, extrusion design, metal reinforcing, and other determinants of quality are hidden from view, however, the best approach is to stick with an established manufacturer and to look for a certification label from the American Architectural Manufacturers Association (AAMA).

AAMA established a separate standard for vinyl windows in 1997, which includes tests for strength, dimensional stability, strength of corner welds, heat and impact resistance, and weathering. The main features to look for include:

Heat-welded corners
Metal reinforcing, particularly on larger units
Solid, heavy extrusions with little obvious flex
Good quality hardware

Installation Procedure for Vinyl Windows

As reported in Best Practices Guide to Residential Construction Chapter 3, BEST PRACTICES GUIDE: WINDOWS & DOORS:

High Rate of Thermal Expansion in Vinyl Windows

In general, vinyl windows install the same as other flange-type windows, although the installer must take into account vinyl’s high rate of thermal expansion.

A 6-foot-wide window can expand as much as 5/16 inch from 0°F to 100°F. To prevent problems, It is best to leave a 1/8 - to 1/4 -inch gap between the window and siding or wood trim (more in cold weather, less in hot). Good detailing of this joint is especially important with stucco, which can crack if set too tightly against the window or leak if the caulk joint fails.

Thermal expansion can also cause window sash to bind in hot weather if the rough opening is too small to accommodate the movement. And in very cold weather, some vinyl windows can bow inward due to temperature differences on either side of the window.

Sturdy extrusion profiles with metal reinforcing can help prevent this. A related concern is sagging of the sill during hot weather— vinyl starts to soften and distort at about 165°F, a temperature easily reached on the surface of a dark building in direct sun. To prevent sagging, some manufacturers reinforce the sill, and all recommend specific shim spacing under the sill.

Some vinyl window installations require continuous support along the length of the sill, which is easiest to achieve by using a double 2x sill with leveling shims in between.

Vinyl Window Nailing Recommendations

Nailing recommendations for vinyl windows also vary among manufacturers. Some recommend driving nails tight; some suggest leaving the nail heads proud. Some recommend against nailing the head flange or corners; others require it. To avoid warranty problems, it is always best to closely follow the manufacturer’s instructions regarding the rough opening, shimming, nailing, and other installation details. Other general recommendations that apply to all windows include:

In hot weather, do not store vinyl windows in a container, such as a trailer, or lean them against a wall, as they can permanently deform.
Seal around openings with flexible flashing before installing the window (see Window Flashing & Sealing Guide).
Set the nailing fin in a bead of high-quality caulking.
Before nailing, make sure the side jambs are plumb and do not bow in or out in the center. Some installers use a wood spacer to hold the two side jambs parallel.
Do not puncture the nailing fin when installing trim or siding.
Do not use expanding foam to seal around the window frame on the interior.

Also see WINDOW TYPES - Photo Guide.

Industry Associations for Windows & Doors

American Architectural Manufacturers Association (AAMA) www.aamanet.org

Efficient Windows Collaborative www.efficientwindows.org

National Fenestration Rating Council (NFRC) www.nfrc.org Sustainable by Design www.susdesign.com

Shareware calculators for sun angles, solar heat gain, and shading

Window and Door Manufacturers Association (WDMA) www.wdma.com

-- Adapted and paraphrased, edited, and supplemented, with permission from Best Practices Guide to Residential Construction.

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Technical Reviewers & References

InspectAPedia.com^® - Daniel Friedman - Publisher & Editor.
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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  VINYL WINDOWS
  VINYL / PVC WINDOW WARPING

  WINDOW MATERIALS & CONSTRUCTION
    Aluminum Cladding on Wood Windows
    Fiberglass Clad Windows
    Vinyl Cladding on Wood Windows
    VINYL WINDOWS
    Wood and Clad-Wood Windows

Basic Housing Inspection, US DHEW, S 352.75 U48, p.144, out of print, but is available in most state libraries; New York State version, ca 1955, source of our window parts and window repair sketches.
Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspect ion services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for adaptations, quotations, or reproductions used at this website. All rights and contents of the JLC material are ©Journal of Light Construction and may not be reproduced in any form.
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Windows, Vinyl Guide

Construction of Solid Vinyl Windows

Vinyl Window Options

Quality Issues with Vinyl Windows

Installation Procedure for Vinyl Windows

High Rate of Thermal Expansion in Vinyl Windows

Vinyl Window Nailing Recommendations

Industry Associations for Windows & Doors

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair