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Marvin Ultrex Fiberglass Guide

Marvin is a brand known universally for quality and style. They offer a variety of window styles across numerous lines, with many customizable features to suit any homeowner’s needs. When you purchase a Marvin product, you know you’re giving your home a top-of-the-line upgrade.

Marvin Ultrex windows installed on a sundeck

Marvin has built its reputation on decades of quality and innovation. Marvin products feature one of the most revolutionary materials in the industry, Ultrex fiberglass, which is among its biggest innovations. But what’s so game-changing about Ultrex? We’ll break it down for you.

About Marvin Ultrex Fiberglass

Which Marvin window lines offer Ultrex?

Marvin Integrity & Infinity windows and doors are made with Ultrex pultruded fiberglass, a material innovation pioneered over 20 years ago by Marvin. Integrity leads the industry with a commitment to a product that is tough, smart, long-lasting and worry-free. It’s stronger than vinyl and won’t warp or fade over time, so it’s practically maintenance-free! You should feel comfortable selecting any Marvin product made from Ultrex to protect the inside and outside of your home.

So, what is it made of?

Ultrex fiberglass is made from fiberglass strands, protruded fiberglass, and a patented acrylic cap to keep its distinct color. It’s essentially thin strands of strong glass cables, which is saturated with compounded resins to create a more durable material.

Marvin uses diamond-edge blades to cut your custom window to size. It’s rigid in a good way, meaning the window will have a true and perfect fit that lasts. It’s virtually indestructible.

The Ultrex pultruded fiberglass that goes into every Integrity window and door remains stable in extreme temperatures and expands at nearly the same rate as glass, resulting in windows that are strong and true.

Fun fact: Boats, bridges, and hard hats are other items made from molded fiberglass!

Which Ultrex product is right for my home?

Typically replacement window shoppers prefer to keep the style and/or appearance of their current windows. So if you already have white fiberglass windows, chances are you’ll be shopping for All-Ultrex. If your home is older, you may have a set of beautiful wood windows, and in that case you’ll want to continue with a set of Wood-Ultrex replacements to keep the same look.

Ultrex windows vs. Vinyl windows

Ultrex is a superior material to vinyl in a number of fascinating ways. Here’s what Marvin thinks you need to know:

  • Ultrex is 8X stronger than vinyl
  • Ultrex windows have a 38% longer useful life expectancy than vinyl
  • Ultrex windows have a clean glazing bead profile and have solid, square, watertight joints. Vinyl corners can arrive with messy welded corners and joints that aren’t square
  • Ultrex windows come in a number of dark colors (a rare opportunity), which are not available in vinyl
  • Ultrex can be painted, while vinyl can not
  • Ultrex can mimic the look of wood from afar, while vinyl can not
  • Vinyl is more affordable than Ultrex, so expect to pay 30% more for the higher quality window
  • Ultrex windows offer more glass space than vinyl
    • More material is needed to support a vinyl window frame, and inhibits the total glass area
  • Ultrex windows have a higher resale value as they are a better window

What makes Ultrex so special?

Ultrex is super strong

To repeat, Ultrex is 8X stronger than vinyl! It’s stress-tested and one square inch of the stuff could support the weight of two monster trucks (that’s 34,000 pounds). It bends and flexes in even the most extreme conditions while keeping its integrity. Want proof? Ultrex resists distortion even at temperatures up to 285°F. Rapid temperature change doesn’t faze Ultrex: When the mercury climbs from -30°F to 70°F, a 6’ stile changes less than 1 /32″ in length.

Ultrex is durable

With a finish that is 3 times thicker than competitive finishes, Ultrex won’t crack, dent, chip or peel. Issues of instability and less-than-perfect alignment that can complicate installation — and long-term performance — are not a concern with Integrity windows It is paintable and virtually maintenance-free. It can even come in dark colors as it has superior fade resistance and UV degradation.

Fun fact: Windows with black interior and exterior can bring a modern look to your home. They’re a popular option right now!

Ultrex is energy-efficient

According to the Sustainable Energy Coalition, compared to single pane unglazed windows, Integrity’s dual pane windows made from Ultrex with Low E coating can reduce window heat loss and cut costs by up to 34% in cold climates, and cut cooling costs by up to 38% in warm climates.

Ultrex is 5000 times less conductive than aluminum. That means winter sun will be allowed in through the winter, and summer sun is reflected back out. Keeping your bills down and your temperature right where it should be.

Ultrex expands at virtually the same rate as glass which means these windows stay tight and true making them resistant to leaks, seal failures and stress cracks that can compromise energy efficiency and long-term performance.

Ultrex is weather-proof

Homeowners along the East coast or living in hurricane zones should feel confident choosing Ultrex windows. The Impact Line of Integrity Windows is IZ3 Rated. The IZ3 (Impact Zone 3) icon demonstrates that the window has passed every extensive test required to be used in Atlantic and Gulf Coast hurricane zones.

All Ultrex vs. Wood Ultrex

Marvin sells two different styles of Integrity windows called “All Ultrex” and “Wood Ultrex”. An All Ultrex window utilizes the patented material we’ve discussed on both the interior and exterior of the frame. It’s strong and durable. The Wood Ultrex window has a gorgeous wood-clad interior and an Ultrex exterior. A wood window brings expert craftsmanship and beauty into your home.

Also consider the age of your home. Do you live in a historic neighborhood? Is your home designated as such and must preserve its original exterior properties? In that case, the Wood-Ultrex is an easy (and mandated) choice.

Wood windows typically cost 20% more than fiberglass windows, so consider your budget when making the selection.

Marvin Ultrex Fiberglass Pricing

The following are approximate costs for Marvin windows, including installation:

  • Marvin Integrity Wood-Ultrex Double Hung Windows: Prices starting from $950
  • Marvin Integrity Wood-Ultrex Casement Windows: Prices starting from $900
  • Marvin Integrity Wood-Ultrex Awning Windows: Prices starting from $875
  • Marvin Integrity All Ultrex Double Hung Windows: Prices starting from $875
  • Marvin Integrity All Ultrex Casement Windows: Prices starting from $950
  • Marvin Integrity All Ultrex Awning Windows: Prices starting from $1119

Ultrex warranty

You’ll have complete peace-of-mind when buying from Marvin. Backed by their never wavering focus on customer service, Marvin Ultrex windows have a 20-year warranty on glass seals with a 10-year warranty on manufacturer defects.

A must-watch video:
Marvin is deadly serious when it comes to testing Ultrex material and pushing it to its limits. The following video showcases just how far they’ve gone:

If you’d like to learn more about your window replacement options, speak to a HireHaven expert today. Call us at 888.392.4236 or visit to get started.