Are all Vinyl Replacement Windows created equally? Hardly. When someone asks me "how much does a window cost", I think to myself, "how long is a piece of string"?
You can literally line up 10 windows in a row and when you stand back, they all look pretty much the same. There in lies the problem. How do you know the difference? Vinyl composites are different. Weatherstrippings are worlds apart. Color additives are many and varied, but the most important factor, the seal between the panes of glass, can be the difference between enjoying easier cleaning and reducing your energy bills vs. a permanently foggy window and no fuel savings.
The advent of what was then called the "thermal pane" window included a double pane glass package with a small dead air space (about 1/4") with a seal composed of glass itself. Two panes were glued to a type of glass tubing , sealing the dead air space and stopping conduction. It worked...for a while. Glass expands and contracts. Let's say it's a hot day in August. The glass temperature could easily rise to over 100 degrees. On a cold day in the winter the temperature could drop to less than zero! Expansion and contraction are going on like crazy, eventually breaking the glued seal, allowing water vapor and dirt, etc. into the air space. The final result is a dirty, foggy, window that has lost it's thermal integrity. Fortunately, few companies, if any, use this process anymore.
The next generation of thermalized windows involved a dual pane glass unit with an aluminum spacer bar and a rubberized adhesive.. Though this design is still often used today, the problems are the same. Expansion and contraction of glass happens at one rate, while aluminum does so at another rate. The constant pushing and pulling will eventually break the seal, creating the same problems as the glass seal. Believe it or not, most lower end windows, such as the ones available at lumber yards and the big box stores, are still made this way. Buyer beware.
In the mid 1980's, glass technology really began to improve. Manufacturers were experimenting with a variety of materials that could stand up to the temperature variances windows are subject to. A product called "Swiggle", otherwise known as Poly Iso Butylene, had been used in the auto industry to seal windshields into cars. The substance is very sticky and quite pliable, but most importantly it was able to withstand the huge swings in temperature without expanding or contracting. Throughout the late 80's and well into the 1990's, Swiggle was widely used as the sealant of choice in premium vinyl replacement windows. Due to the organic nature of this product, drying eventually occurred and seal failure became a problem. Many top manufacturers have abandoned Swiggle as viable sealant, though others have continued to try to perfect it. A new design incorporating an acrylic outer seal, encapsulating Swiggle as an inner seal has been very effective and long lasting. A small number of companies are using this method today.
The most common spacer used in replacement windows today is the Intercept Seal. This seal is a "U" shaped metal alloy spacer bar. The theory here is that as the glass expands and contracts,the u shaped channel will flex in and out, without stress on the glass or sealant. While the theory is good and this design is very popular, the seal is still metal, and has the potential to expand or contract enough to cause inevitable seal failure. When used in conjunction with Argon or Krypton, the gas was found to have totally dissipated in 5 years. More than 70% of replacement windows today use this design, both in double and triple pane products.
The newest innovation in glass sealants is the Super Spacer by Edgetech . Developed in the late 1990's, this spacer is a foam product infused with butyl. It has the ability to flex with expansion and contraction, without the negative properties of a metal bar. In a 5 year study, seal failure with the Super Spacer was less than 3%, far below the failure rate of aluminum (40%) or Intercept (14%). When used in conjunction with Argon gas or Krypton, gas retention was about 70% in 5 years. Most Super Spacer glass units are guaranteed for 20 years plus. If you want a product you'll only need to purchase once, I recommend the Super Spacer.
Once again you get what you pay for. Ask your contractor or window specialist about Super Spacer. The popular intercept seal is widely available in all price levels, But, after all, if you buy a product because it's a little cheaper and it ends up not doing what you bought it to do, it's just more money wasted. For more information on Super Spacer, watch this video.
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