Vinyl-Windows.org

Vinyl is Widely Reported to Fail in Sunlight and Heat

We have gathered some interesting reports from around the world that point to vinyl windows not being able to withstand sunlight and heat.

“Ultraviolet (UV) light can fade colors other than white and cause yellowing and “crazing” in the plastic’s surface. Vinyl frames are also not very rigid. Vinyl windows with large openings usually require an internal metal extrusion to make the frame stiffer. This can lower the frame’s R-value significantly. Vinyl window frames can also soften, warp, and twist if heat builds up within the frame. In very hot sunny climates direct exposure to sunlight is not recommended.” U.S. Department of Energy.

“Solid vinyl windows are an inexpensive last resort. Give them about 10 years and the vinyl will become faded and brittle from exposure to sunlight and temperature.” Teaman Architectural Newsletter, 1999

“PVC (vinyl) expands and contracts and can warp due to heat.” Nation’s Window’s Windows 101, 1999

“All vinyl becomes brittle in extreme cold. It expands and softens in heat.” Reader’s digest New Do It Yourself Manual

“Vinyl frames are not strong. Vinyl frames get soft and warp. They are dimensionally unstable causing warping, cracks, air leaks which cause thermal failure and glass fogging.” Washington Post, April 21, 1996

vinyl window reviews

The following articles contain information on window frames. This bibliography was reviewed in November 2002.

“Are Wood Windows on Their Way Out?” A. Wilson, Progressive Architecture, pp. 112-14, June 1994.

“Consumer Guide to Energy-Saving Windows” J. Warner, Home Energy, (7:4) pp. 17-22, July/August 1990.

“Energy-Efficient Window Retrofits: Install with Care” J. O’Bannon and A. Grieco, Home Energy, (14:1) pp. 35-42, January/February 1997.

“Energy Ratings Given for Windows, Doors” Professional Builder, (60:6) pp 66, April 1995.

“How to Avoid Window Condensation” J. Warner, Home Energy, (8:5) pp 27-29, September/October 1991.

“More Than One Way to Case a Wiindow,” J. Beals, Fine Homebuilding, (98) pp. 54-59, October/November 1995

“Predicting Window Condensation Potential” A. McGowan, ASHRAE Journal, (98) pp 24-29, July 1995

“Replacement Windows” Consumer Reports, (58:10) pp 664-67, October 1993.

“Selecting Windows for Energy Efficiency” J. Warner, Home Energy, (12:4) pp 11-17, July/August 1995.

“Shopping for Wood Windows” C. Wardell, Journal of Light Construction, (12:9) pp 27-34, June 1994.

“Taking a Look at Windows” J. Kolle, Fine Homebuilding, (No. 97) pp 56-61, August/September 1995.

Consumer reports on vinyl windows

Consumer Reports, October 1993, “Vinyl sash tracks became distorted during durability tests. Parts of the frame and sash bowed during durability tests. We experienced glass seal failure during durability tests.”

Popular Science, June 1995, “Although vinyl is more energy efficient than aluminum, vinyl, can warp and fade.”

Reader’s digest New Do It Yourself Manual, “All vinyl becomes brittle in extreme cold. It expands and softens in heat.”

Washington Post, April 21, 1996, “Vinyl frames are not strong. Vinyl frames get soft and warp. They are dimensionally unstable causing warping, cracks, air leaks which cause thermal failure and glass fogging.”

Boston Globe, November 16, 1995, “Be aware of replacement windows. I’ve seen entire buildings full of replacement windows with manufacturers who have gone out of business. This happened commonly during the boom of the 80’s. Now these windows are starting to fail. These are usually the low-end vinyl replacements which are sold by hundreds of companies each year.”

This Old House Press Release “Worrisome Windows”, “Consumers are inundated with ads from regional window companies that promise miracles. Maintenance free windows made of sturdy vinyl will not rot, pit, rust or wear out. Such claims have helped make replacement windows a $3 billion industry. Many of those windows will not last as long as the ones they replaced. There are fewer than 10 major window manufacturers in the US but more than 3000 companies making windows. If you and I wanted, we could do it in our garage.”

This Old House Press Release “Worrisome Windows”, “Vinyl softens at 165˚, A Temperature easily achievable in the space between drapes and the windows on a sunny day. Vinyl expands and contracts 7 times more than glass. This action can pop seals between frames and glass. Vinyl is simply not suitable on its own as a window material. Says Mike Compleu of Anderson Window Corp who has never made an all vinyl window.”

vinyl window reviews

Washington Post, April 21, 1996, “Vinyl frames are not strong. Vinyl frames get soft and warp. They are dimensionally unstable causing warping, cracks, air leaks which cause thermal failure and glass fogging.”

US Dept. of Energy-National Renewable Energy Lab, October 1994, “Vinyl material tested warped, shrunk and twisted. Vinyl cannot withstand extreme temperature fluctuations.”

US Dept. of Energy-NREL, August 30, 1996, “Vinyl frames are not strong or rigid, which limits the weight of glass that can be used. In addition, vinyl frames can warp, soften twist and bow.”

Environmental Building News, 1999, “We evaluated all the framing material used in windows and advised to avoid 100% vinyl window frames because of their durability problems. Vinyl windows have only been on the market in the US for 15 or 20 years. Many of these products won’t even last a decade.”

Grolier Encyclopedia 1993, “PVC (vinyl) softens and warps at 158˚ F.”

Window Review 1995 “Careful consideration is necessary when choosing replacement windows.”

Builder Magazine, June 1998, “Windows and doors are the #1 source of dissatisfaction among new homeowners.”

Consumer Reports, October 1993, “Vinyl sash tracks became distorted during durability tests. Parts of the frame and sash bowed during durability tests. We experienced glass seal failure during durability tests.”

Popular Science, June 1995, “Although vinyl is more energy efficient than aluminum, vinyl, can warp and fade.”

Reader’s digest New Do It Yourself Manual, “All vinyl becomes brittle in extreme cold. It expands and softens in heat.”

City of Oakland, California, February 1999 “Passed a resolution to reduce and phase out the use of PVC (vinyl) recommends non-PVC alternatives”.

Dutch EPA Hearings, 1997 “PVC windows are not regarded as a favorable material for windows under sustainable construction programs”.

Ireland 1998 “Passed an initiative to eliminate the use of all PVC (vinyl) windows and doors.”

OEAKF Austria 1997, The Standardization of PVC Window Frame Recycling “60 tons of PVC (vinyl) window frames are collected each year. PVC (vinyl) window frames are taken back for free if the customer buys wood windows to replace them. The cost of recycling is paid by the manufacturer”.

Fenestration Magazine, Vol. 6, No. 5, “UV or IR (infrared) wavelength of sunlight Affects PVC (vinyl). UV affects the impact strength and color retention of the window. The more critical factor is that heat build up from IR can cause distortion of PVC framing.”

Fenestration Magazine, May/June 1993, “What happens to PVC (vinyl) in warmer regions of the US? Will heat turn the framing into soft, melted material? Will the windows change color from white to yellow or  brown to beige? If it’s hit with an object, will a piece break off? Rigid PVC is brittle and discolors under UV light. Other concerns are wind-loads.”

Aluminum Extruders Council, 1997, “A “60” long PVC (vinyl) frame member at 120 degrees will stretch over ¼” from expansion and contraction. Movement between components such as glass and frame over time can lead to distortion and seal failure, air and water leakage.”

Boston Globe, November 16, 1995, “Be aware of replacement windows. I’ve seen entire buildings full of replacement windows with manufacturers who have gone out of business. This happened commonly during the boom of the 80’s. Now these windows are starting to fail. These are usually the low-end vinyl replacements which are sold by hundreds of companies each year.”

Consumer Energy Information: EREC Reference Briefs

Window Frames

For very old windows the frame and glazing had almost the same R-value (about R-1). Modern glass technology has improved the insulating performance (R-value) of the glazing itself (Typically R-3 to 8). What the frame of the window is made of has come to dominate how well the window performs overall. Modern window frames are constructed from a variety of materials including steel, aluminum, wood, vinyl and composites such as fiberglass and epoxy resin. Each material has advantages and disadvantages.

Metals

Metal window frames are ideal for openings that require lightweight and strength. However, all metals are very good conductors of heat (R values hundreds of times less than 1). Even metal framed windows with plastic “Thermal breaks” (a plastic strip that separates the exterior side of the frame from the room side) only improve the R-value slightly. There are no metal-framed windows currently available that are comparable in thermal performance to any of the other choices in window frames. Also, unless protected by special finishes, metal frames can oxidize (rust).

Wood

Wooden window frames are better insulating than metal frames (about R-1.4 per inch of thickness) and help to prevent cold weather condensation problems inside the house. However wood does require maintenance (i.e. painting). If they aren’t protected from moisture, they can stick, crack, and rot.

Aluminum-clad and Vinyl-clad Wood

Some manufacturers protect their wood frames by wrapping them with vinyl or aluminum. This helps keep wood window maintenance low. However, if the cladding should come loose and expose the wood to water, it can still rot. The thermal performance is about the same as an ordinary wood frame.

Wood-Plastic composites

Some companies make frames out of a mixture of wood, vinyl and an epoxy adhesive. Such frames are very strong, insulate well, and resist rot even when exposed to water frequently. The insulation value is about the same as an ordinary wood frame.

Vinyl

Vinyl frames are primarily made from Polyvinyl Chloride (PVC). Some manufacturers fill the hollow parts of the fame with foam or fiberglass insulation too. Data shows that the difference in performance between filled and hollow vinyl frames is small. Generally vinyl frames of all types are slightly less of a thermal insulator than wood.

Vinyl frames are also available in many styles and are generally considered low maintenance and they never need painting. However, the ultraviolet (UV) light can fade colors other than white and cause yellowing and “crazing” in the plastic’s surface. Vinyl frames are also not very rigid. Vinyl windows with large openings usually requite an internal metal extrusion to make the frame stiffer. This can lower the frame’s R-value significantly. Vinyl window frames can also soften, warp, and twist if heat builds up within the fame. In very hot sunny climates direct exposure to sunlight is not recommended.

Fiberglass

Fiberglass frames are made of a fiberglass and resin composite. Some frames are hollow; others are filled with fiberglass insulation. Most are pre-finished with a polyurethane coating. Such frames are about R-3.

Fiberglass frames are resistant to warping, shrinking, and rotting. Fiberglass window frames are also relatively strong and durable and can hold a large expanse of glass. You can specify almost any color you desire. You can also paint them.

However, they may not be widely available, as there are few companies manufacturing them currently, and the long-term performance is still unknown. Fiberglass window frames also cost more than the other types of window frames.

Frame Construction

Some windows are divided into small sections of glazing or “divided lights”. A divided light window is considerably less energy efficient than other types because of the large number of glazing edges. However, modern multi-pane windows are often whole sheets of glass with optional plastic or wood grilles that attach to the glazing to give the appearance of a divided light window.

The insulation value of a double-pane or triple-pane window is primarily a product of the air space between the panes of glass. Spacers separate the panes at the edges. Until recently, most edge spacers were made of metal, which means the edge of the window has little or no insulating value. Many manufacturers now use improved edge seals with much better thermal performance.

Metal and vinyl frame corners may be welded or screwed together. Either one is acceptable. However, welding a corner can often distort the weather-stripping groove. Always check how well the weather-stripping meets at the corners. There must be no gaps. Wood frames are often “finger-joined” and glued to make a strong corner.

Window frames are rated A, B, or C according to their performance in an American Society of Testing and Materials (ASTM) “aging” test that involves exposure to UV light, moisture, and extreme temperatures. “A” rated windows are the best performers.

Summary

Improving the comfort and energy use of a building are the primary factors in deciding to replace windows. Carefully consider your climate, budget, and availability, maintenance, and style of window. You should also check for durability, quality, and warranties. Check the local building department’s requirements regarding egress, safety glass, and window grade before buying. The purchase of the right windows can go far in turning a drafty home into a comfortable and more energy-efficient one.

Bibliography

The following articles contain information on window frames. This bibliography was reviewed in November 2002.

“Are Wood Windows on Their Way Out?” A. Wilson, Progressive Architecture, pp. 112-14, June 1994.

“Consumer Guide to Energy-Saving Windows” J. Warner, Home Energy, (7:4) pp. 17-22, July/August 1990.

“Energy-Efficient Window Retrofits: Install with Care” J. O’Bannon and A. Grieco, Home Energy, (14:1) pp. 35-42, January/February 1997.

“Energy Ratings Given for Windows, Doors” Professional Builder, (60:6) pp 66, April 1995.

“How to Avoid Window Condensation” J. Warner, Home Energy, (8:5) pp 27-29, September/October 1991.

“More Than One Way to Case a Wiindow,” J. Beals, Fine Homebuilding, (98) pp. 54-59, October/November 1995

“Predicting Window Condensation Potential” A. McGowan, ASHRAE Journal, (98) pp 24-29, July 1995

“Replacement Windows” Consumer Reports, (58:10) pp 664-67, October 1993.

“Selecting Windows for Energy Efficiency” J. Warner, Home Energy, (12:4) pp 11-17, July/August 1995.

“Shopping for Wood Windows” C. Wardell, Journal of Light Construction, (12:9) pp 27-34, June 1994.

“Taking a Look at Windows” J. Kolle, Fine Homebuilding, (No. 97) pp 56-61, August/September 1995.