Are Fiberglass Windows the Right Choice For You?

Are Fiberglass Windows the Right Choice For You?

June 7, 2021
Martin Whitmore, President of US Window & Door
fiberglass windows in modern home with a view

If you are looking for a home window replacement in San Diego, you must have heard of fiberglass windows.

Fiberglass windows are on the rise and are among the most popular window materials in the US. If you've never heard of them or thought they might be too expensive for your home, think again. Even though fiberglass windows tend to be more expensive than other window materials, such as vinyl, you must consider other benefits. 

Understanding what fiberglass windows have to offer can help you determine whether they are the right choice for your home window. Here are all of the important considerations and questions to ask before replacing your windows.

The Perks of Fiberglass Windows

We place a lot of demands on our windows. When they're open, they're supposed to let in light and fresh air, and when they're closed, they're supposed to shut out the rain, cold, and heat. With all these demands, we also expect them to continue to work well for decades.

Wood windows have served a lot of homeowners well in covering these demands through the years, but even with low-maintenance exterior cladding, the wood tends to swell and shrink in response to temperature changes, hence, compromising its durability.

ultra series fiberglass windows

Vinyl windows eliminate maintenance concerns, but this material offers less glass area due to potentially thicker frames. It also loses its resiliency as it ages, which can pose longevity concerns when compared to fiberglass.

On the other hand, fiberglass windows do not have these limitations. It's more rigid and lighter than wood, requires less maintenance like vinyl, and is resistant to water and temperature changes. Though early fiberglass models had some drawbacks, advances in manufacturing have addressed those issues.

For most homeowners, the main alternatives are to choose between vinyl or fiberglass windows, but this is not always an easy choice. There are a few important things homeowners need to consider when choosing windows.

The purpose of this article is to discuss the advantages and disadvantages of fiberglass to help you make the right choice for your home, budget, and lifestyle. Knowing more about the advantages and disadvantages of different types of windows can help you make an informed purchasing decision.

Natural Light

Fiberglass frames tend to be a little thinner than vinyl frames, allowing more space in rooms where you want to let as much natural light in as possible.

Similar Sturdiness as Wood

Fiberglass and PVC windows have been around for a long time, and recent developments in fiberglass windows have made them even more durable and efficient. Fiberglass is inherently a robust and durable material, with high strength/weight ratio and high rigidity. In a very intricate process, a resin injector is merged into the glass fibers through a weft insert and placed in a material line with supreme strength. The procedure supports the otherwise delicate glass and fashions a new material that is much sturdier than wood or vinyl. The frame of fiberglass windows supports the large panes and produces a high-quality, durable glass window.

In addition to the strength of fiberglass, its longevity has been proven by its durability in a variety of applications in different fields, such as automotive, medical, and industrial.

With so many applications, fiberglass offers many advantages and is one of the most versatile materials available on the market today.

The strength and durability of this material allow it to withstand different weather conditions, which means that they do not expand or contract due to weather changes, and the glass remains intact.

Compared to wood, which has to be regularly sealed, painted, and patched, fiberglass windows are practically maintenance-free.

Moreover, replacing existing windows with fiberglass windows is a good choice because they are stronger and more durable than vinyl windows. Fiberglass is also the better choice if you plan on selling your house. 


The stiffness and strength of the fiber-reinforced resin - means that window frames and sashes can be narrower and less bulky without compromising on their structural integrity. This reduces the likelihood of leaks in the window frame and minimizes damage to the glass.

Energy Efficiency

Fiberglass windows are energy efficient and are manufactured to withstand extreme heat and cold. It provides better insulation than the vinyl windows and saves you from paying hefty electricity bills.

By incorporating double and triple glass panes, you can increase the energy efficiency of your fiberglass windows and maximize energy conservation. Fiberglass windows absorb heat and, thus, help to maintain the right temperature and climate within your home. As glass is an insulator, fiberglass offers the same advantage but has a much higher insulating capability than glass, including great thermal conductivity.

Fiberglass is moisture resistant, so there is no concern about rot, corrosion, mold, or swelling. Fiberglass frames are low maintenance, and they do not warp, making it difficult to damage the frame or other parts of the structure, such as the glass.

Questions To Ask Before Getting a Fiberglass Window

fiberglass windows ultra series in lliving room

"Am I Willing To Pay A Lot Of Money?"

Fiberglass windows can be expensive compared to simple glass windows, but they are generally cheaper than wood. Vinyl windows, on the other hand, are significantly cheaper, but you will need to pay more to boost their strength and durability. You can expect to pay more for a 1 / 4-inch-thick window with a glass frame, and you will need to install a durable coating. On average, fiberglass windows cost about half the price of aluminum-clad wood and often cost less than wooden windows. Plus, when you factor in the savings in maintenance, repair, and energy costs, fiberglass can be more affordable than you think.

Fiberglass windows are generally more costly than vinyl windows and considered on the high-end level for window options as it is more durable than other window materials such as wood, aluminum, and vinyl. Ultimately, a vinyl window could become a more expensive investment than a fiberglass window in the long term if you need to replace them more often, so consider long-term expenses and don't simply choose based on the initial costs.

"Do I Have Standard-Sized Windows?"

fiberglass window sliding

Fiberglass boasts impeccable durability. However, this also means that it is difficult to cut and shape. Trimming fiberglass presents a challenge for windows that are not standard in size.

Fiberglass can be an option if the window is standard-sized. Compared to wood, fiberglass is harder to transform into a unique shape and profile.

The pultrusion process only produces straight parts, but recent advancements have allowed manufacturers to now shape fiberglass into classic arches using spikes and curves. Those who want other colors or shades can choose to paint fiberglass. Window combinations no longer need to be combined into bays, arches, or other combination sets; they can be supplied as integrated units.

More than a decade ago, fiberglass windows were limited in terms of size and color options. Today, there is a much wider range of colors in custom sizes, but because the material is so new, few manufacturers produce it, resulting in a long lead time.

Fiberglass windows now offer more design versatility with the flexibility to be cut into any shape or size to fit your needs. One of the main reasons why homeowners choose fiberglass windows is that it allows for solid, customized designs, and the durability of fiberglass can supplement any weakened areas that other materials may have.

"Am I Alright With the Possibility That My Painted Fiberglass Windows Will Peel and Fade?"

Although fiberglass frames do not need to be repainted for maintenance, the material can be painted if you choose to alter the color scheme. So, if you want the advantages of a fiberglass window but can't find one in a color that works for you or just want to give your windows a fresh new look, there's a solution. With most windows, stains and paint eventually crack and peel off, requiring new windows, but Milgard's fiberglass windows can easily be repainted, making it easy to maintain the fiberglass frames throughout the window's lifetime.

Is A Fiberglass Window The Right Choice?

Fiberglass windows are not always an easy choice, and there are various considerations a homeowner should look into before choosing them. Fiberglass windows are the perfect choice for your home if you want maximum strength with great design flexibility. There is now nearly no limit to styling when it comes to meeting your aesthetic requirements. You can rely on the expertise of our contractors to find the best option for you and decide whether fiberglass windows are the right choice for your home improvement project or not.

At US Window & Door, we use Milgard's top-of-the-line fiberglass model from the Ultra Series for our windows and frames. Browse our many window style options and learn more about the advantages of installing our fiberglass line in your home today.