What are the best windows for the Colorado climate?

Double Hung Window - 3 Wide Mull

The answer is simple...

Fiberglass Windows

We know fiberglass windows are the best replacement solution for Colorado's Climate.  But not just any fiberglass.  Our Infinity from Marvin fiberglass window is made from ULTREX.  Marvin's Patented ULTREX fiberglass is the strongest fiberglass on the market.

Ultrex fiberglass - a pultruded fiberglass material





Ultrex pultruded fiberglass, a material patented nearly 20 years ago when Marvin pioneered the fiberglass windows and door category. Infinity windows have led the category ever since with a commitment to a product that is tough, smart, long lasting, and worry-free.


We don’t just claim that Ultrex pultruded fiberglass is the toughest window material available; we prove it. Through a variety of punishing tests in harsh conditions, Infinity windows made with Ultrex comes out on top again and again. Watch this video and see just how tough Ultrex really is!

Built Clean

Ultrex is made from silica sand – a safe and abundant natural resource. The Ultrex manufacturing facilities fully comply with the 1990 Clean Air Act and are designated as a Maximum Achievable Control Technology (MACT) facility as outlined by the EPA.  Read more here

Read more about Infinity from Marvin's Sustainability here


Compare the Difference

Not every company installs windows and doors the right way. First, our installers have all the necessary equipment and installation experience to do the job right from the get-go. Next, when in your home, we follow simple steps like using drop cloths and tarps, dust mitigation, blind removal, and re-installation, and we even wash the windows. Finally, once your project is complete, our guys will walk you through your home and show you how to operate your new windows and doors.


At Gravina's Window Center of Littleton, our installers have more than 50 years of window installation experience. Our installers are OUR installers. We do not sub out our window and door installations. They are experts and craftsmen that are well trained and certified. They are not handymen or storm chasers that other companies may use.

Comparing Windows Through the NFRC

When comparing windows, it is important to consider a window energy rating system based on whole product performance. Windows with the National Fenestration Rating Council (NFRC) provides the only reliable way to determine the window energy properties to compare products. The NFRC performance label can determine how well a product will perform the functions of cooling your home in the summer, warming your home in the winter, keeping out the wind and resisting condensation. The U-Factor is a better indicator of window performance than R-Value. A lower U-Factor rating indicates better insulation properties. Infinity from Marvin replacement windows has one of the highest performance ratings from the NFRC.

Infinity from Marvin replacement windows exceeds industry standards for air, water, and structural performance.
The ENERGY STAR rating from the U.S. Department of Energy and the U.S. Environmental Protection Agency is only granted to products that reduce energy usage to mandated levels. Infinity from Marvin exceeds the performance requirements and qualifies for the ENERGY STAR rating in all U.S. climate regions. When comparing other windows, be sure it is rated for our region of the country.


Window Installation

Installation is a key component of your replacement window or door project. At Gravina's Window Center of Littleton, we know that Poorly installed windows will cause even the highest quality windows to underperform. You will find our technicians to be knowledgeable, courteous, skilled, true craftsmen, easy to work with and willing to work hard to see that your project exceeds your expectations. Also, we have Installation Masters Certification, so we are experts when it comes to different home applications.