Solid PVC or Vinyl Windows:

This article discusses the cause and cure of warping in vinyl or PVC (polyvinyl chloride) windows.

Warping PVC Vinyl Windows, Cause & Prevention

The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article, (see links at the end of this article) from Solar Age Magazine and written by Steven Bliss.

PVC Vinyl Window Warping Q&A

Question: What are the facts about the occurrence of shrinkage and warping in PVC or Solid Vinyl Windows?

I have heard some horror stories about shrinkage and warpage in extruded PVC (polyvinyl chloride) windows.

Can you get some factual information on solid vinyl window shrinking or warping problems? - Roy Berger, Architect Roy Berger and Sun, Des Moines IA

Answer: 

Problems in PVC or vinyl windows can be due to manufacturing or installation procedures, window color, or climate.

According to veteran plastic window maker Dan McCleary (Rehau Plastics, Leesburg VA in 1985), problems in solid vinyl or extruded PVC vinyl windows in the mid 1980's and how vinyl window shrinkage or warping problems were avoided were described:

PVC window units with welded corners can resist the stresses of thermal expansion better than vinyl windows whose components are screwed together with a metal bracket.

Holes punched out of the vinyl window frame for hardware or mounting screws were also a weak point - if the holes were badly punched or were too small, cracks could occur.

PVC (Vinyl) window warpage can be controlled by embedding a steel or aluminum bar inside the window frame, but this approach was considered limited by the size of the window frame. Many of the modern windows in the 1980's had a very narrow sight line - the amount of window frame that extends into the rough opening - which limits the size of metal bar that could be installed.

Window sash and frame color are another factor in PVC Window expansion problems. White or beige vinyl expands less than dark colored PVC because it absorbs less solar radiation.

According to McCleary, vinyl window color is not a problem north of the 50th Parallel in Canada and through most of Europe.

Some solid vinyl window manufacturers use white vinyl for the window core and add a thin overlay of pigmented vinyl that can move around (in response to thermal changes) without damaging the window.

Expansion and contraction problems in windows will be worse if the windows do not have room in their rough opening to expand or contract. Shims and setting screws used to install windows should be placed at least 8 inches back from the window corners to avoid these problems.

This article is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Original aritcle

• Q&A: Warped PVC Windows? - PDF version; use your browser's back button to return to this page. Original article, Solar Age Magazine, October 1985, adapted and updated for InspectAPedia.com December 2010.

Readers should also see VINYL W5INDOWS for details about PVC windows and their proper selection and installation ,

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.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: possible to fix warped PVC or vinyl window frames?

(Apr 28, 2014) mike said:
can warp vinyl window frames be fix

Reply:

Mike,

I very seriously doubt that it's cost-reasonable to fix warped vinyl window sashes and frames. Once these components have re-shaped themselves, usually in response to heat, even trying to straighten them is likely to break the window itself. Furthermore, the plastic has taken a set and won't happily return to a stable, straight and square condition. The result is constant aggravation with leaks, hard-to-operate sashes and worse.

If you can't live with the window as is I'd replace it. And check into a warranty claim.

Question: banging window sounds

(May 8, 2014) Ann said:
I'm in rented property and the double glazed window has started to bang during the day and night

Reply:

Ann I'm guessing that the frame of the window may be moving due to thermal contraction. Is this problem the same in all seasons and independent of the difference between indoor and outdoor temperature? Are there any cracked window panes in the building?

Question: sagging vinyl windows

(July 17, 2014) S Hall said:
Our vinyl windows have sagged from the top so much that we can see the installation screws above the window. The sash has also sagged downward so that our windows will no longer lock. These were new construction windows 15 years ago and we have a lifetime warranty that the company will not honor.

The company says they were not installed properly by not allowing enough room for expansion, however they did not measure the window opening. I really don't understand how they can say the opening wasn't the correct size if they never measured for it. They say their windows can not warp and its never an issue. Everyone that has looked at our windows can see that the vinyl has warped and sagged. Is there a guideline to use to tell if the vinyl has broken down and warped and am I correct in expecting them to measure the window opening to determine the proper installation. Any advice on where to go for help. Thanks.

Reply:

S H

I agree that a warranty denial based on a telephone inspection is not very credible. Use our CONTACT link to send me some sharp photos and I'll comment further. You might also research the window brand and model online (as I will when you provide that information) to see if other owners have had similar experience.

In addition to a possible produce vulnerability to high temperatures, if vinyl windows or doors are dark in color and/or covered by storm windows or storm doors, the solar collector effect of that installation can indeed cause warping damage such as you describe.

- moderator

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Continue reading at WINDOW EFFICIENCY FEATURES & RATINGS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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