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White home interior with Marvin Replacement Casement picture windows.

Vinyl vs. Fiberglass Windows

You can face a tough decision when it comes to choosing replacement window materials. Fiberglass and vinyl remain two of the more popular options, but they feature some key differences that set Marvin Replacement fiberglass windows apart. Here’s what to know about fiberglass vs. vinyl windows.

Fiberglass Windows Overview

Fiberglass window material is made through a process called pultrusion. Pultruded fiberglass is a thermoset material made through a chemical process. A thermoset fiberglass composite won’t soften or melt in environmental temperatures, making it more resistant to pressure and temperature than vinyl composites.  

Closeup of the construction of Ultrex fiberglass

Fiberglass Windows at a Glance 

At Marvin Replacement, we go one step further with our proprietary Ultrex® fiberglass windows. Ultrex fiberglass is made by taking thin strands of glass cables and saturating them in specifically compounded resins. The material is pulled through a series of shaping dies that form the sash or frame profiles, passes through a heated die, and then our proprietary acrylic finish is applied. The material is cut with diamond-edge blades due to its strength.

Fiberglass Windows Pros

Fiberglass windows have several advantages over other window materials. Our Ultrex fiberglass improves upon fiberglass windows with increased strength and low expansion rate.

Ultrex fiberglass windows pros

  • Low expansion rate—meaning your windows won’t warp, so they’ll open and close smoothly

  • Exceptional strength—Ultrex offers superior bending and flexing resistance to protect the integrity of your home. Other window materials can start to sag and create issues with your home

  • Fade resistant—Our Ultrex finish withstands up to 48,000 hours of sunlight without fading*

*Average sunlight exposure per 10 years.

Vinyl Windows Overview

Vinyl is a type of plastic made from ethylene and chlorine that when combined make polyvinyl chloride (PVC) resin. It has become the second-most manufactured and sold plastic resin in the world. You can find vinyl in things like old records and vinyl fabric. 

Vinyl Window Pros + Cons

Vinyl windows remain a popular option for homeowners because of their lower cost, low-maintenance, and easy installation. Vinyl windows have some disadvantages, though.

Vinyl Window Pros

  • Low-maintenance—Vinyl windows rarely need painting or sanding, and are easy to clean

  • Available at big box retailers—Vinyl windows are easy to find off-the-shelf at home improvement stores

  • Lower costs—Vinyl’s low cost makes it attractive to homeowners, but low prices can also mean low quality

Vinyl Window Cons

  • Shorter lifespan—Vinyl windows have a shorter useful life expectancy compared to fiberglass windows1

  • Expansion—Can expand in hot weather and contract in cold weather, which can impact energy efficiency and air leakage

  • Less durability—Vinyl can chip or dent when impacted, making a window unsightly and lead to replacement

Are Fiberglass Windows Better than Vinyl? Vinyl and Fiberglass Window Differences

When you’re deciding on a window material for your home it’s important to know the differences between fiberglass vs vinyl windows. Fiberglass and vinyl windows share some characteristics, but they can differ in areas like lifespan, energy efficiency, and appearance.

Vinyl vs. Fiberglass Durability + Lifespan

Marvin Replacement’s Ultrex fiberglass offers the strongest window material in the replacement industry so you can count on its durability. Vinyl has a shorter lifespan and doesn’t offer the same protection as fiberglass when it comes to handling extreme temperatures. Vinyl can start to soften at 163° F while Ultrex fiberglass can withstand temperatures up to 285° F without losing its shape.

Fiberglass vs. Vinyl Window Appearance

Fiberglass windows and vinyl windows can look similar. The properties of Ultrex, however, can make it more resistant to fading and other imperfections. If you ever wanted to change the color of your windows, you can paint fiberglass windows.  Painting vinyl windows has more difficulty because you need specific paint that will adhere to vinyl since it expands and contracts.

Ultrex fiberglass windows looks

  • Ultrex’s superior strength also means less material is needed for the frame, so you enjoy more glass area to let natural light into your home

  • Ultrex’s acrylic finish is three times thicker than competitors, which makes it more resistant to pinholes, scratches, and other imperfections

  • Our optional EverWood® wood grain interior finish matches the natural look and texture of wood but without the maintenance

Vinyl windows appearance

  • Vinyl can offer a range of colors to fit a home

  • Vinyl lacks the character that EverWood and wood provide

  • Vinyl windows have become so ubiquitous that some homeowners seek different window materials to set their homes apart

Why is Ultrex Fiberglass Stronger than Vinyl?  

Comparison of Ultrex fiberglass strength and vinyl windows

Fiberglass vs. Vinyl Window Maintenance

Both fiberglass and vinyl windows require little to no maintenance. See our tips on how to clean fiberglass windows.

Fiberglass vs. Vinyl Value 

Vinyl windows may have a lower price point, but they have a shorter lifespan, and can suffer from expansion and contraction. A shorter lifespan and the contraction and expansion issues could lead to spending more on windows over the life of your home.  

Replacing windows has a 61-68% recovery rate on your investment when you sell your home.  

Ready for a Bigger, Brighter View?

Ready to invite Marvin Replacement Ultrex fiberglass windows into your home? Choose from a variety of replacement window options to make your home welcoming.  

1 “Life cycle assessment of windows for the North American residential market: Case study” by the University of British Columbia. Scandinavian Journal of Forest Research, 2008.

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