Fiberglass is one of the most popular window materials on the market, but the price tag is usually a little higher than most other options.

Infinity Ultrex Fiberglass Graphic

So are fiberglass windows worth it? Let’s break down the pros and cons.

Pros of Fiberglass Windows

Not Affected by Temperature

Heat can melt other window materials and cold can make some materials brittle and cause breakage. That isn’t the case with fiberglass. Temperature doesn’t cause shrinking, swelling, or sagging in fiberglass, so you know your windows will keep a tight seal and be resistant to leaks around the edges.


Fiberglass is waterproof so there is no opportunity for water to permeate it causing rot, mold, or swelling due to moisture or humidity. Fiberglass frames also don’t have any seams that can collect gunk.

More Sunlight, Wider View

Fiberglass is stronger than most window materials. Because of this, less material can be used. This results in narrower window frames and the opportunity for more glass space in your windows when compared to other materials. You’ll notice a big difference if you have wood or vinyl windows and switch them out for fiberglass - the wider view is incredibly noticeable.

Infinity Frame Ultrex Vinyl Graphic

Strength Against Impact

With eight times the strength of vinyl, fiberglass can stand up to wind, hail, and even stray baseballs. Glass fibers (as suggested by the name) are woven through the material to reinforce it, giving it significant strength.

Vinyl vs fiberglass window strengthvinyl vs fiberglass window strength comparison


Fiberglass windows are often said to “last a lifetime.” Their warranties generally last twenty years or even for the time you own the home. Some studies show fiberglass is expected to last up to fifty years.

Low Maintenance

Fiberglass windows don't need to be continuously stained and sealed to protect against weather and wear and tear like wood windows do!

Best Energy Efficiency

Since fiberglass doesn’t expand or contract and doesn’t transfer heat or cold, it is an exceptional insulator. In fact, the same fiberglass that is used in windows is used for insulation material in attics! Fiberglass is extremely energy efficient and about 15% better than vinyl windows at insulating your home. And being less likely to form air gaps makes them 30% more energy efficient.

Best Sound Insulation

Just as they insulate for energy, fiberglass windows also insulate against sound. There is no opportunity for seal leaks and air gaps to form over time since they retain their shape and size, keeping your home quiet from street noises.

More Options for Style and Color

Fiberglass window frames come in a wide variety of styles and colors. The frames can also be painted to update to match the decor of your home. This is a big asset when compared to other popular window materials such as vinyl, which come in very limited colors and cannot be painted or stained.

Mimic the appearance of wood

Because fiberglass can more closely mimic the look of wood windows, they are well suited for the aesthetics of your home and maintaining historic design and matching original decor in older homes.

Increases home value

Fiberglass windows increase your home’s value because they are a high quality product that have a long lifespan and are not likely to need repairs or maintenance.



Fewer Options

While fiberglass has more customization options than vinyl, it has fewer options than wood in color and hardware.

Not as easy to find

Fiberglass windows aren’t typically sold in stores and may only be carried by a few companies in your area. This means you may have a longer wait time or have to hire a company that is farther away.


Fiberglass windows typically cost 10-30% more than other window types.

Susceptible to UV light

IF your fiberglass windows aren’t powder-coated, they will fade over time and need to be painted. Selecting a good coating - or ensuring the company does this already, will prevent UV rays from damaging your window.

Professional Installation is Necessary

Fiberglass windows are more rigid than other windows. This makes them more difficult to install and precision is required. DIY installation is much more challenging and not recommended for homeowners.


Analyzing the Pros and ConsInfinity Ultrex Finish Comp Graphic

When you understand the pros and cons, it's easier to decide if fiberglass windows are a good fit for your home. With superior strength, low maintenance requirements, and customization options, they are a popular choice for homeowners. While they are more expensive than vinyl windows, they are more affordable than clad wood - another high-quality material option.

We’ve done a lot of research on fiberglass windows over the years. Because of this, we have chosen to carry Ultrex fiberglass windows made by Infinity from Marvin. Ultrex is a special kind of patented fiberglass that increases the benefits even further by contracting at less than half the rate of other fiberglass window options. It also has a smoother, less porous finish which allows the frame to be more resistant to UV damage.

We also believe in carefully training our installers so they can expertly fit your windows to your home. How your window is just as important as the window material quality to ensuring you receive the maximum benefits of energy efficiency, longevity, and noise cancellation.


Interested in learning more about your window options? Check out these other blog topics:

Types of Window Coatings and What Works Best For Your Home
How Do I Know If My Home Needs New Windows
How to Know If Your Windows are Damaged
Considering Vinyl Windows? Know the Cost, Quality, and Comparisons