Why Fiberglass Windows are Better than Vinyl

Whether you’re buying new construction or renovating an older home, at some point you’ll need to select either new or replacement windows. At first it may seem that finding the best window style for your home is the most urgent decision. However, there are many other factors to consider, including the window frame material, type of glass panes, and your budget. Which type of window will provide the best performance and most value? Wood windows are the most expensive, and require the most upkeep. Unless they have a historic home or high-end project, most homeowners today choose either vinyl or fiberglass window frames. While both fiberglass and vinyl windows are durable, energy-efficient, and low-maintenance, each one has its pros and cons. Read on to learn more about how these windows are made, what they cost, and which type of window material may be best for your home.

What Are Vinyl Windows?

Vinyl window frames are the least expensive of all current window options. They are made from PVC (polyvinyl chloride), the same durable material that is used for siding, fences, plumbing and gutters. Vinyl is affordable, low maintenance, resists scratching and can last for decades. It’s more flexible than wood, aluminum or fiberglass, so vinyl window installation is less complicated. Because it’s less expensive and fits more easily into existing window openings, vinyl is a popular material for replacement windows. However, due to its flexibility, vinyl is not a suitable material for very large window walls.

What Are Fiberglass Windows?

Fiberglass window frames are made from a combination of polymers and glass fibers, just like the durable fiberglass used to make boats. Because the fibers add strength, fiberglass is stiffer and more impact-resistant than vinyl or wood. Marvin is the industry’s leading manufacturer of fiberglass windows. They pioneered the use of fiberglass for window and door frames, creating Ultrex fiberglass which is eight times stronger than vinyl.

This ultra-durable formula makes excellent window frame material because it resists bending, breaking, dents, or chips, even on very large windows. Its inherent strength allows fiberglass windows to have narrower frames that preserve the view.

Fiberglass is also non-conductive, so it won’t transfer heat between indoors and outside. This increases energy efficiency and helps maintain consistent temperatures throughout a room. Fiberglass is available in a wider range of colors than vinyl and can also be painted to match your home. The only maintenance required is occasional repainting if you choose a painted finish.

Fiberglass vs. Vinyl Windows Comparison


Style & Color Options

Even though most of your window area is glass, the type of window frame you choose can make a big difference in your home’s appearance and curb appeal. Vinyl windows typically have wider frames; the corners are welded together and the seam may be visible. Because vinyl is less rigid, it can’t support very large expanses of glass. For this reason vinyl windows are only available in traditional styles, such as double hung windows or Palladian windows that have a dividing bar to add strength.

Home with white vinyl windows

Vinyl windows do not offer a wide variety of colors; white is most common, but beige, bronze, and black are also available. Muntins (the vertical and/or horizontal dividers that separate the glass into a grid), may be added. Because of their plain appearance vinyl windows don’t exactly replicate traditional wood windows; however, vinyl replacement windows are still a valuable home improvement.

Fiberglass windows have a larger variety of colors to choose from, and if you change your home’s exterior color scheme in the future, they can be painted to match. Because fiberglass composite frames can support large panes of glass they are a popular choice for modern homes with large window walls. If you want replacement windows that will bring in plenty of natural light, consider upgrading your home improvement project to include fiberglass windows.

Marvin Essentials Fiberglass Windows

Marvin Windows offers two different types of fiberglass window frames: Ultrex® fiberglass and high-density fiberglass.

Ultrex Fiberglass is a durable fiberglass proprietary to Marvin that is eight times stronger than vinyl. It is used for the exteriors of Marvin Elevate products and the interiors and exteriors of Marvin Essential products.


Marvin High-Density fiberglass shares many of the same characteristics of Ultrex but is even stronger. Used for the exteriors of Marvin Modern products, it mimics the clean look, feel, and strength of aluminum and steel, while providing better insulation.


While prices will vary from one project to the next, vinyl windows are usually the least expensive choice for both new construction and replacement windows. Fiberglass windows can cost anywhere from 10% to 30% more than vinyl, because the materials, manufacturing and installation are more expensive and complex.

Energy Efficiency

While both vinyl and fiberglass windows are energy-efficient, fiberglass offers superior insulation. The glass fibers added to the fiberglass keep the material from expanding and contracting (which can cause leaking), and it does not conduct heat or cold. This makes fiberglass a better insulator than vinyl, which is less stable and will transfer differences in temperature between indoors and out. Fiberglass is also an excellent noise insulator, making it a better choice for areas with traffic noise.


Vinyl is more likely to develop air gaps over time, which account for up to 30% of the energy loss that affects heating or cooling your home. Both types of window frames incorporate energy efficient glazing systems for increased energy savings.

Durability & Lifespan

Both fiberglass and vinyl window frames are very low maintenance and long-lasting. However, PVC is a thermoplastic material, meaning that products are created by melting the plastic and letting it harden again. Because of this, vinyl window frames can warp when exposed to very high temperatures, resulting in seal failure. Vinyl window frames also have welded joints at the corners so they have less structural integrity than fiberglass frames, which are solid. Like any product, vinyl windows do vary in quality, and the cheapest grades of window have been known to fail after as little as ten years. Still, it is possible to find a high quality vinyl window that’s designed to safely withstand high winds and last up to 30 years. Proper maintenance, such as using caulk to fill gaps in the frame, is essential for a long lifespan.

Fiberglass window frames are engineered to last 50 years. The glass fibers in fiberglass make it stronger and stiffer, so it can support larger glass panes in narrower frames and still maintain its structural integrity. Fiberglass also expands and contracts at about the same rate as glass, even in extreme temperatures. Because of this, fiberglass is extremely stable and maintains its seal ,preventing the air leaks that cause other windows to fail over time.


Which type of window provides the most value? To calculate the ROI (return on investment) of home improvement projects, determine how much of the cost will be recouped by an increase in the home’s market value. For example, if you spend $10,000 on new windows and your home increases in value by $8,500, that’s an 85% ROI.

Depending on their features and quality, vinyl windows have an ROI of 68 - 74%*, making them an excellent investment in your home. Fiberglass windows can have an ROI as high as 85% because of their extended lifespan. When you factor in additional savings gained from improved energy efficiency, high-quality windows are well worth the expense.

Shop For Marvin Fiberglass Windows At Ring’s End

Upgrade your home with fiberglass windows that never need replacing! As the premier resource for Marvin fiberglass windows in the Northeast, Ring’s End offers an extensive selection of designer windows and doors in our 9 beautiful showrooms across Connecticut and Westchester, New York.

Our free in-store consultations make it easy to learn more about doors and windows for your home or schedule an in-home appointment and we’ll come to you. Our team has the knowledge and expertise to help you find the perfect window style, size and finish. Request a quote today!

Ring’s End also offers direct window installation on both new construction homes and renovations. Our installers are licensed and fully insured. They follow the manufacturer’s recommended installation methods, to ensure each window we install meets the manufacturer’s warranty criteria. Our installers are certified as EPA Lead Safety Renovators. Registered in Connecticut, New York (Westchester County), and Rhode Island, our installers deliver the highest quality services throughout the region. Click here for more information.

Window Frame FAQs

What is the longevity of vinyl vs fiberglass windows?

Vinyl windows have a lifespan of 20-30 years, while fiberglass windows can last 50 years.

What is the cost difference between vinyl and fiberglass windows?

Fiberglass windows typically cost 15-30% more than vinyl windows, including installation.

Which window type is better for insulation?

Fiberglass window frames are extremely stable and will not transfer temperatures between indoors and outside. Vinyl windows do not insulate well, so they can transfer extreme temperatures from outside to inside.

Which windows are better, vinyl or fiberglass?

Fiberglass window frames are generally considered to be the best available, but high quality vinyl windows can be an excellent choice if the budget is limited.


*Cost vs. Value Report, 2022 https://www.remodeling.hw.net/cost-vs-value/2022/middle-atlantic/