Compare The Best Fiberglass Replacement Windows


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Best Fiberglass Replacement Windows

We've put together four of the best fiberglass replacement windows currently available. Find product descriptions, contractor opinions and pricing, which ranges from $550 to $800 installed.

Alpen 925 Window

The Alpen 925 series is their best fiberglass window model from Alpen and delivers up to a 9.1 R-value and 99.5% UV protection. It is one of the top rated fiberglass models on the market and also one of the most expensive. The window can be ordered as a casement, awning, fixed frame, half circle, bow or bay, and sliding patio door. It includes all of the grid and SDL options, as well as the paint and finish options of the 525 and 725 series. The casement window with the Alpine glass 9L will deliver a .15 U factor, 6.7 R-value, .22 SHGC and a .34 VT. These are some pretty fantastic numbers, but obviously it does come at a price.

Price Range: $800 to $1100 Installed

Marvin Infinity Series

The Marvin Infinity has an Ultrex fiberglass frame that comes as either a full Ultrex or as an exterior Ultrex with an Everwood interior (this is a wood veneer that looks very similar to wood, without any of the maintenance). The Infinity is a replacement window, although it is probably available as a full frame replacement given some customization. The Infinity is more expensive than the Integrity and has a thicker frame, some better "bells and whistles", a better finish to the frame and a better warranty (lifetime on everything except the glass, which is 20 years). The performance numbers on the Infinity are good (but not great); U-factor of 0.30. The Infinity is the better window and if you can afford it and don't have to have wood, this is a good quality window.

Price Range: $675 to $775 Installed

Inline Fiberglass Windows

Inline windows is one of the lesser known but higher end fiberglass window manufacturers that is headquartered in Canada. Their products are not cheap, but are well made and designed. Their products have a thin profile to maximize glass area, use Cardinal glass, quality paint ,100% pultruded fiberglass frames, and a high quality screen. Inline is priced out using the stripped down window as the base price - every upgrade you add to it - glass, fills, screens, hardware, warranty adds to the base price for a per unit final price. The company gets knocked for some outdated hardware and limitations on sizes and dimensions.

Price Range: $700 to $1000 Installed

Milgard Ultra Series

The Milgard Ultra is their fibeglass window and often considered a second choice behind the Infinity or Integrity. The Ultra lacks the the fantastic look of the Infinity Everwood, which is their wood veneer interior. One positive of the Ultra is a real wood interior option (just as the Integrity is available in the wood interior). The company offers a nice warranty on their products. If the Marvin products are out of your price range and you are married to fiberglass, the Milgard is a decent choice.

Price Range: $550 to $650 Installed

Marvin Integrity Series

The Marvin Integrity is their slightly lower end fiberglass frame that comes as either a full Ultrex or an exterior Ultrex with a real wood interior. There are far fewer options available in the Intgrity, both in terms of sizing, colors, hardware etc. While it is a nice looking window, most industry insiders feel it's not as nice as the Infinity (and has less of the bells and whistles of the Infinity). It should come standard with a Cardinal glass package (20 year warranty on glass), has a lifetime warranty on the frame and 10 years on defects. A good option for homeowners who want a wood interior with a fiberglass exterior at a reasonable cost.

Price Range: $600 to $700 Installed

Pella Impervia Series

The Pella Impervia is a fiberglass frame that has a clean, thin profile and is available in custom sizing (although some contractors are put off by both the fit and finish of this window). It is available as a double hung and casement - some customer didn't like the look of the double hung. The Pella has less than stellar performance numbers (U-value of 0.33) which is not particularly impressive. It uses a mid range metallic spacer and is priced somewhat high based on comparable offerings.

Price Range: $700 to $800 installed

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