Are Fiberglass Windows Worth the Investment?

Are Fiberglass Windows Worth the Investment?

May 3, 2021
Martin Whitmore, President of US Window & Door
ultra series fiberglass windows in kitchen.

Unfortunately, most homeowners cannot avoid the cost of replacing a window, and upgrading to another material doesn't always feel like a better value.

Choosing the right material for a replacement window is an important decision, and is just as important as the quality of the window. Style, function, insulation, and durability are largely determined by the window material. So when it comes to choosing the right material for your window frame, the options are overwhelming and it can be tempting to get a good bargain. 

Vinyl is widely popular because it is one of the cheapest window materials on the market. What many homeowners don't realize, however, is that fiberglass windows often offer better value. 

Fiberglass was long used as an ultra-strong and lightweight material for the production of skis, surfboards, canoes, etc., and began to gain popularity only around the year 2000. It was originally intended to remove certain restrictions on PVC or Vinyl windows in terms of its material capabilities.. Fiberglass windows are a great investment, and it is worth it for many reasons, such as durability, and cost savings, to name a few. In this article, we will tackle more reasons why investing in fiberglass windows would be worthwhile investment.

Differences Between Fiberglass, Vinyl, and Wooden Windows

Fiberglass Windows are becoming more and more popular and they perform extremely well compared to other window materials. Newer fiberglass windows like the so-called Fiberglass composites consist of a mixture of fiberglass and polyester resins. As the name suggests, fiberglass is made of glass fibers that retain their integrity even at hot temperatures. Glass fibers in Fiberglass are formed when a catalyst activates a polyester resin, which is then pulled out of a heated die. Glass strands and glass mats are impregnated with resins, re-coated and then shaped to get the end result called a lineal. 

Here is a brief overview comparison of the differences between Fiberglass and other material types in the market.

vinyl windows for your home

Fiberglass Vs. Wood

High-quality wooden windows have lower maintenance costs and improved durability, but are more susceptible to wear than their fiberglass counterparts. If your wooden windows are broken, damaged, or warped, it may be time to think about replacing your windows as windows in poor condition will only get worse.

Fiberglass Vs.Vinyl

Vinyl windows are among the most commonly installed windows in homes. When it comes to energy efficiency, fiberglass windows achieve the same energy efficiency as vinyl windows, making them a more attractive option. Fiberglass is also stronger than vinyl. It is made in such a way that it is very similar to wood, albeit in different colors. Fibreglass does not expand and contract while vinyl can eventually lead to cracks and warping over time. Moreover, vinyl loses its resistance over time, while fiberglass does not have this disadvantage. 

milgard aluminum windows

Aluminum Vs. Vinyl

Aluminum is a terrible insulator that easily transports heat from the outside to the inside in winter unlike fiberglass. This is why these extruded metal window types, although they are lightweight, are only suitable for mild climates, and are best suited for high-end homes with high ceilings, high windows and large windows.


Fiberglass windows are most often preferred due to their low cost, high performance, and long service life. If you look at the benefits of fiberglass windows, you will find that they stack differently from wood or vinyl. When we compare the longevity of fibreglass windows with PVC or wooden windows, a significant difference becomes apparent. We will discuss the expected service life of fiberglass windows and compare them with other materials.

Most PVC windows and aluminium windows will probably last 15 to 20 years before they need to be replaced. Fiberglass windows can last up to 50 years or more if installed and maintained properly. If the investment looks steep, it pays off, especially if it spans a few decades. The same amount for fiberglass (about $10,000 for a single window or $20,500 for an entire house with multiple windows) lasts twice as long as the cheaper windows.

Fiberglass is eight times stronger than vinyl, which means that it lasts much longer when properly maintained. Fiberglass windows can last 50 years or more, however, a good quality Vinyl window can also last up to 30 years. 

Due to the strength of fiberglass, its durability has been proven and its frame cannot be damaged even in the most extreme weather conditions. The reason for the superior strength of fiberglass is its composition: the frame is made of some kind of plastic. The fiberglass frame reinforces the glass, which gives the product considerable strength. This means that the window may have a thinner frame and more are for the glass, but it is still stronger than a glass window. In a very deliberate process, the resin injector is knitted into the glass fibre by a weft insert and positioned in a material line with maximum strength. This process strengthens the otherwise fragile glass and creates a completely new material that is many times stronger than vinyl or wood. The fiberglass frame holds the large panes of the window and creates a striking, high-quality, and durable glass window with a high degree of durability.

Thermal Performance

Energy efficiency is a major concern for many modern homeowners, and upgrading your windows with fiberglass can go a long way to making your home more comfortable and efficient. Fiberglass windows have earned an impressive reputation as energy-saving windows due to their low cost, high insulation, and high energy efficiency.

Fiberglass is a better insulator than vinyl by 15% more. The glass fiber provides low conductivity without thermal interruption and can be seen when compared to other window materials. In addition, fewer air gaps are created over time, which accounts for a significant proportion of the energy used to heat and cool your home. Because the window seals are so strong and remain intact, they are among the most energy-efficient type of window on the market. They do not easily transfer heat, lead to air leaks, and they can reduce excessive energy costs and create a comfortable home around the clock.

ultra series fiberglass windows

Vinyl has the same insulating properties, which means that heat from the outside can more easily penetrate through the frame. It also provides a better energy insulator and because glass fibers do not expand and contract like other materials, the seal of the product lasts much longer, making fiberglass much more wear-resistant. Because of its superior insulating properties, fiberglass is also less susceptible to impact than other material types.

High performance fiberglass windows are stiffer, stable, and great at slowing the heat flow. The material does not readily transfer heat from the outside to the inside, which can prevent heat losses due to heat absorption and heat transfer. The same fiberglass material used for insulating your attic is also in your frame, which means that the frame is more energy efficient. Adding glass fibers to a fiberglass window frame means that it does not expand, contract, or transmit heat or cold. For this reason, fiberglass is considered a more environmentally friendly choice, but may be more expensive than other materials.

Flexible Style Options

  • Discuss specific style options clients have with fiberglass. 
  • Describe the Milgard Ultra Series. 

Fiberglass is also an extremely versatile material, as it can be embedded in a variety of applications such as glasses, eyewear, and even clothing and accessories. You can choose from a variety of styles, colors, and finishes, and if you want more personalization, a more unique fiberglass style can be achieved through customization options. Fiberglass windows have many color options which do not fade, flake, cause problems or require maintenance. 

The Milgard Ultra™ Series | C650 Fiberglass Windows are robust, beautiful, offering contemporary fiberglass window options that are built to last for decades. Create the home of your dreams. Within and out, the fiberglass frames of the UltraTM Series windows and patio doors come in four exterior colors. A white interior can be combined with any exterior paint. In Harmony, Bark, or the common Black Bean, you can color-match both the interior and exterior colors. The Ultra Series also  has a wide range of grid forms, patterns, and variations to choose from. The grids you pick will match the color of your windows' exterior fiberglass frames.

ultra fiberglass windows exterior

Fiberglass windows also have frame options that mimic the look of wooden windows which are smoother than vinyl. There are a few differences between vinyl frames and fiberglass, but from a distance the two are relatively similar. Vinyl windows have obvious connecting lines in their corners and are not as smooth as fibreglass. Fiberglass window frames can support larger panes of glass in a slender frame so you can install a generous living room window with partitions without obstructing the view.

Sound Resistance

Fiberglass window frames are great noise insulators due to the same glass fibers that make them great energy insulators. Fiberglass is one of the most effective noise insulators on the market.  Foam insulation may be applied to fiberglass windows to help minimize sound propagation. Quality frames come with insulating air chambers and optional foam insulation to help keep noise out. Proper installation ensures airtight seals and reduces noise transmission. Since vinyl does not have the same insulating properties as wood, noise from the outside can be more easily transmitted via the frame.

Request a Free Fiberglass Quote

Windows are often the most important factor in determining the sale price of a home, especially when its condition plays a part. Fiberglass windows are good products, which are a better choice than wood when choosing a new window construction or replacement. They tend to fetch higher resale values than PVC or vinyl windows. Vinyl has some advantages, especially when the price is the main factor which is why it is more often preferred over fiberglass. Fiberglass may be more expensive on average than other materials such as wood or vinyl, but it is more durable.

Fiberglass windows are the best choice for their appearance and power. Consider contacting US Window & Door if you're looking for window replacement. We take pride in providing friendly and knowledgeable service to our customers while also meeting their window needs to a high standard.