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Composite vs. Fiberglass: Andersen 100 Series & Pella Impervia

Published: Sept. 11, 2023

DunRite Compares The Two Most Popular High-End Windows

In the world of high-end windows, it can be hard to come up with an apples-to-apples comparison across the different manufacturers. According to experts here at DunRite Windows & Doors, who installs thousands of windows across the Phoenix Metro area every year, two of our most popular products are the Andersen® Windows 100 Series, and Pella’s® Impervia® series.

So how do they compare? Let’s take a look.


Different Materials & Distinctive Styles

These two products are fairly similar in terms of how long you can expect them to last, and their energy efficiency. However, they are dramatically different in the materials used for the frame, which in turn, gives each one its own unique style.

The Andersen 100 Series is made of a proprietary composite that combines reclaimed wood fiber and a thermoplastic polymer called Fibrex®. It’s an improvement over vinyl, since it’s stronger and lasts longer, it handles extreme heat temperatures up to 150 degrees without sagging or warping, and the finish never needs painting or refinishing. The caveat? It’s a thick frame, with an average width of three inches per side, leaving less viewable glass area. It’s a distinctive look that not all homeowners prefer.

In contrast, Pella Impervia windows are made with a fiberglass frame that’s the strongest in the industry, making it perfect for large sized openings. It has an attractive modern look, with a thin frame that gives it a maximum glass viewing area. It’s a window with a tidy, clean appearance that’s ideal for a modern appearance. Originally designed for commercial buildings, the Impervia line is suitable for any climate, ranging from -40 degrees to 180 degrees. They come in a wider array of colors than the 100 Series.

DunRite Owner Sal Sucato speaks highly of Pella’s quality and customer service, and likes the clean mitered corners of the Impervia product.

Unlike vinyl windows, both products can be customized to have a different color on the frame interior versus the exterior. White interiors with a black or neutral exterior are a popular choice.  Both can be expected to last 40 years or more.

When comparing the style, the different appearance of the Andersen’s 100 Series and Pella’s Impervia windows can be a motivating factor why a homeowner might choose one or the other.

Price can also be a factor, since the Andersen 100 Series costs less than Pella Impervia.

Both are excellent products with a robust warranty, and highly recommended.


Excellent Energy Efficiency

Now on to one of the most important features that every Sonoran Desert homeowner wants to know: energy efficiency.

If we compare a base product that’s similar across both brands, say a sliding glass window with Low-E3 glass, the NFRC ratings are very similar. Using data provided to authorized dealers when ordering product, the Andersen 100 Series comes in at a 0.29 U-Factor, which rates the amount of heat lost, and the Pella Impervia has a slight improvement at 0.27. The SHGC for both products is exactly the same at 0.21, which is a metric measuring the window’s solar heat gain.

These products are both excellent in terms of overall energy efficiency, which can be improved even further with available upgrades.


Introducing the new Andersen 100 Series Flush Fin       

While we’re on the topic of Andersen Windows, they launched a new addition to the 100 Series this year: the flush fin window. Perfect for stucco homes, which are so common to the Phoenix area, a flush fin window slides right over an existing aluminum frame into a window opening, with a flange on the exterior that frames the opening and hides the original frame.

A stucco fin is common to vinyl windows from other brands installed by DunRite, such as Anlin and Milgard, and similar to the Renewal by Andersen product, but new to the Fibrex line.

It’s manufactured in the Andersen Goodyear, AZ facility and as an Andersen Authorized Dealer, DunRite is trained in its installation, and covered by Andersen’s two-year dealer installation guarantee, along with DunRite’s standard lifetime installation guarantee and the product manufacturer’s warranty.

For pricing and detail on which replacement window product might best fit your budget and style preferences, schedule an in-home estimate today! You can also learn more about shopping for replacement windows in our Ultimate Shopping Guide or free eBook.  Don’t forget to check our home page for any sales promotions we might be offering!


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Please note that we install replacement windows and doors, but we don’t repair them or replace broken glass. Three-item minimum purchase, some doors excluded. Refer to our FAQ and warranties page for details.


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