Ultrex Fiberglass Gravinas Littleton

Infinity Fiberglass Replacement Windows – Made from Ultrex



Infinity windows and doors are built with Ultrex ®, a highly durable, state-of-the-art, pultruded fiberglass that significantly outlasts and outperforms vinyl and vinyl/wood composites in virtually every way. This pioneering technology benefits from over 20 years of proven performance in the field.


Fiberglass Windows in Denver


Infinity windows are superior to all other brands

Infinity from Marvin® has set the standard in fiberglass replacement windows.  Made entirely of Ultrex®  fiberglass, there are many advantages to replacing your old windows with Infinity and here are a few of the key differences that set us apart from the competition.


Infinity’s interior and exterior are made entirely of Ultrex pultruded fiberglass, a material so advanced it outperforms all other window materials in virtually every category:<

  • STRENGTH – 8x stronger than vinyl.
  • NO FINISHING REQUIRED – Ultrex on the interior and exterior.
  • DURABILITY – Ultrex resists rotting, warping, corrosion, or denting and is highly resistant to fading.
  • LOW THERMAL CONDUCTIVITY – 500x less conductive than aluminum; less than 1/3 the conductivity of glass; similar to wood and vinyl.
  • STABILITY – Expansion/contraction is virtually the same as glass which allows for tightly sealed units with the consistently easy operation – resists bending, buckling, twisting, or warping in Colorado’s extreme weather conditions.



Fiberglass materials used in the manufacturing of Infinity from Marvin replacement windows go through a pultrusion process. Pultrusion is a continuous molding process using fiber reinforcement in polyester or thermosetting resin matrices. Heat is used on the “thermoset” resins, in the fiberglass pultrusion process, to cause an irreversible chemical reaction which permanently sets the shape of the fiberglass window frames. Once the Ultrex is cured, it cannot be reformed; this process is permanent.


pultruded fiberglass windows and doors denver


Pultruded fiberglass materials are made of glass fibers and resins. The glass used in fiberglass, while basically the same core material as that used in flat glass, comes in a different form – rovings – or also known as fibers.  This form of glass begins as a finely ground, flour-like material composed of Silica and Zirconia. The “flour” is heated and melted at approximately 1500° C, and the resultant molten glass is passed through small holes forming hair-like filaments. The filaments are collected together, grouped and a binder is applied to bond them into strands. Then the strands are heat cured, wound together and rolled up into a cylindrical package. These fibers provide the bulk of fiberglass profile’s longitudinal strength.


pultruded fiberglass windows and doors


The majority of resins used for fiberglass window profile are classified as polyesters. Polyester resin is one of a group of synthetic resins which undergo polymerization during curing. They provide excellent adhesive properties, high strength, and good chemical resistance. These high-performance polyester resins are then mixed with suitable fillers and pigments to formulate the resinous matrix. The formulations are optimized for the particular application.



Which means that our windows and doors stay tight and true even after extreme temperature swings. Ultrex expands at virtually the same rate as glass and maintains a tight seal, so it’s resistant to leaks, seal failures, and stress cracks that can compromise energy efficiency and long-term performance.






Fiberglass has an amazing strength-to-weight ratio, which is one of the reasons why it’s the material of choice for boats**, bridges, guard rails, and ladders. It’s highly durable, doesn’t corrode, resists rot, and resists expanding and contracting in temperature swings.

* In comparison to longitudinal tensile strength. ** Molded fiberglass

Built For Life!

From Marvin Vice President of Business Development, Dan Marvin:

Infinity windows and doors are made with Ultrex®, a patented pultruded fiberglass with acrylic capping.  We use Ultrex and our proprietary pultrusion process to manufacture high-performance windows and doors that endure heat, cold, wind, and rain without wearing out.

Though we are dedicated to leading the way in innovation, we never forget the cornerstones of our business. We are highly selective in choosing our business partners – independent, locally-owned installing retailers – to ensure our customers have the best experience possible.  Infinity from Marvin creates products to be easily installed and operable with virtually no maintenance required.

Our values and work ethic are forged by the communities where we’re proud to make our quality products. When you choose Infinity windows and doors, you support a small-town, family-owned and operated company with deep roots in the community. We share profits with our employees; we support our communities; we treat our retailers and customers fairly and with respect.

Infinity windows and doors are truly Built For Life.” 


*DISCLAIMERS, LIMITATIONS, AND ADDITIONAL TERMS AND CONDITIONS Disclaimers. This Limited Warranty is the only warranty, written or oral, express or implied, provided by Infinity. No dealer, employee, or agent of Infinity, nor any third party, may create or assume any other liability, obligation, or responsibility on behalf of Infinity. ALL IMPLIED WARRANTIES, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. Any implied warranty which cannot be disclaimed under applicable law will be limited in duration to the shortest permissible term and, in any event, will not exceed the term of the applicable express limited warranty; the requirements for presenting any claim so affected will be as provided in this Limited Warranty. Any product or component not specifically subject to this Limited Warranty or another written Infinity product warranty is provided AS IS and without warranty. This Limited Warranty gives you specific legal rights and you may also have other rights, which may vary from state to state. THIS WARRANTY IS NOT A WARRANTY OF FUTURE PERFORMANCE OR A STATEMENT OF THE USEFUL LIFE OF ANY INFINITY PRODUCT, BUT ONLY A WARRANTY TO REPAIR, REPLACE, OR REFUND. Limitations IN NO EVENT WILL INFINITY BE LIABLE FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES. IN NO EVENT WILL INFINITY’S LIABILITY EXCEED THE PRICE PAID FOR THE AFFECTED PRODUCT OR COMPONENT. The limitations of warranty and liability set forth herein shall survive and apply, even if the exclusive remedy set forth in this Limited Warranty is found to have failed of its essential purpose. Certifications and Ratings Many standard Infinity products are labeled with the Window & Door Manufacturers Association (WDMA) Hallmark Certification. WDMA Certification is based on the performance of a single sample of the product at the time of manufacture. Many standard Infinity products are labeled with National Fenestration Rating Council (NFRC) ratings. NFRC ratings are based on a combination of computer simulations and physical testing of product samples. Certifications and ratings apply to single products only and do not apply to mulled or combined products. Performance of individual products may vary and will change over time, depending upon the conditions of use.