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Made from a safe and natural resource. ULTREX® is made from silica sand one of the strongest & most abundant natural resource in the world - 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.

Better Replacement Windows

Simply put our thin frames makes Infinity from Marvin the most Elegant Replacement Windows in the US. Infinity from Marvin replacement windows is Rated # 1 in 2019 by JD Powers and associates in Customer Satisfaction with window and patio door manufacturing brands. As you compare Infinity from Marvin ULTREX® windows to other manufactures and other window frame material you will discover why Infinity from Marvins ULTREX® windows are the right choice for every home.

Why our Replacement Windows BEAT All Competitors

We make the strongest window replacement frames, with the most elegant finish. Our thick even acrylic finish is free from pinholes, striations, and imperfections and will resists scratches, fading, and chalking to retain its original beauty. Manufactured from a pattened pultruded fiberglass process with a patterned acrylic finish Infinity from Marvin's ULTREX® is as STRONG AS STEEl, 8 times stronger than vinyl window frames and 3 times stronger than composite window frames like Fibrex. Proprietary ULTREX® finish is the highest rated in the industry the first and the only one to have achieved AAMA 624 verification. Our finish performs so well we offer dark colors like black without fear of UV degradation or fading to keep your windows looking beautiful for decades to come. Ultrex® also carries the best energy efficiency ratings in the replacement window industry

Our Replacement Windows are just more Beautiful

Instead of bulky wide and unappealing frames with an unfinished corner, we created thin elegant frames that are built for life. If you compare our beautiful finish to all other window frames you can see the difference in the manufacturing quality, the gorgeous design, the smoothly welded corners, and the ultimate sleek finish. You can choose from 7 interior and exterior color options and 8 wood grain options.

Beauty that lasts

Infinity from Marvin is the only company that applies this proprietary, high-performance, co-extruded acrylic finishing process which is unlike anything else in the industry. Our propriety thick, even acrylic Finish is free of pinholes, striations, and imperfections and will resist scratches, fading, and chalking to retain its original beauty. This propriety acrylic Finnish is applied both to the outside and inside frames for added protection from the harsh sun and weather for decades.

A Finnish That Resists Fading

Want long-term color retention in a variety of styles? Ultrex® uses an acrylic finish that is paintable, fade-resistant and virtually maintenance-free. With a finish that's 3 times thicker than competitive options, Ultrex® resists chipping, denting or peeling.


Vinyl can warp and shift under everyday conditions — potentially making vinyl windows difficult to open and close and affecting their all-around performance. Ultrex® resists sticking, swelling, and warping so Infinity windows and doors will continue to easily open and close.

Vinyl frames must be manufactured thicker wider, bulkier in order to support the heavyweight of the glass. Because vinyl needs thicker wider frames in order to support the heavy dual-pane glass the result is more frame and less viewable glass.

Ultrex® vs. Wood

Wooden windows offer classic beauty that, depending on the environment can require maintenance and care. Infinity windows capture the beautiful details and profiles of wood — without the maintenance.


More view for your money

ULTREX® not only provides unmatched durability compared to other window replacement materials, but it also makes a lasting impression both inside and out. From narrower profiles that deliver bigger views and more daylight to color options that resist fading, Ultrex® simply delivers.

Because ULTREX® is so strong, we actually use less material in Infinity window frames. That means you get more daylight, more view of the outside, more glass, without bulky materials obstructing your view. We pay extra attention to the details that matter — like our clean, non-welded, corners that let you make the most of your beautiful view.

ULTREX® exclusive patented frames are as strong as steel so they are thinner sleeker and more elegant which results in more viewable glass with a sleeker frame.


The Material You Choose for your windows and doors will have impacts far into the future.

Your window and door choice affects your energy efficiency, the security of your home, even the quality of your life. It's not a decision that should be made lightly. Our advice? Study the facts and choose wisely


Vinyl has a high rate of expansion and contraction compared to glass. This can lead to seal failures and stress cracks. Some vinyl/wood composites are 60% vinyl infused with wood fibers and struggle from similar performance issues as their vinyl counterparts.


Infinity windows and doors are built with Ultrex®, a highly durable, state-of-the-art, pultruded material with acrylic capping. This pioneering technology benefits from 20 years of proven performance in the field


UlLTREX® windows are as strong as steel, our frames are manufactured thinner, trimer, and sleeker because they are strong. Thinner, sleeker frames result in more viewable glass.

ULTREX® expands at a 4.0 virtually the same rate as glass, at a 4.6 so our windows stay tight and true. This makes Infinity windows resistant to leaks, seal failures, and stress cracks that can compromise energy efficiency and long-term performance.

Compared to other materials, Ultrex® is the strongest window framing material in the replacement industry. This means Ultrex® resists bending and flexing — that's confidence Fibrex® and vinyl simply can't match.



Why don't they make boats out of vinyl?

Because a boat made out of vinyl would be a very bad idea. Between the beating and pounding of the boat against the water and the heat of the sun, the vinyl would break apart on the first trip to Catalina.

Vinyl frames expand and contract. Vinyl is a soft material subject to chipping, peeling, cracking, fading, and can warp and shift under everyday conditions — potentially making vinyl windows difficult to open and close and affecting their all-around performance.


ULTREX® for unmatched performance

We created Ultrex® with one goal in mind: develop the most durable window material in the industry. It's not only 8 times stronger than vinyl — it resists expanding and contracting in any climate. So you get a tight, snug fit that will last.

Vinyl Window Frames Expand and Contract: Vinyl materials are great for many different products, like patio chairs and lawn furniture. However what happens to plastic furniture when you leave it in the sun for a few years? It starts chalking and deteriorates, it warps and falls apart in just a few years. There is a reason boats are made from fiberglass because they take the beating of the ocean waves, the heat of the sun, and the cold of the water, and ULTREX® just keeps going. Window Replacement is made for Fiberglass because it's strong and it lasts.


Compare Other Composite Windows

Compare Fibrex® material is made from 60% vinyl and 40% wood products mixed together to attempt to make a stronger vinyl window. It is the best vinyl window you will find it's 3 times stronger than most other vinyl windows, however, it is still a vinyl window and is subject to the same problems that vinyl windows have.

They don't have a protective acrylic coating like Infinity from Marvin's ULTREX® frames so the colors are subject to fading in the sun over time and it can be subject to the same problems as other vinyl windows. Compare the performance of the Fibrex material to ULTREX® in the chart above created by Stork Technimet Corporation an independent unbiased testing facility.

Reviewing the expansion and contraction chart above, vinyl windows expand and contract 8 times more than the glass they surround, Fibrex only expands and contracts 4 times more than the glass that it surrounds so it does do a better job than most other vinyl windows, however, it still expands and contracts 4 times more than the glass. Infinity from Marvins ULTREX® frames expand and contract at almost the same rate as the glass so the frames do not pull away from the frames and cause the seal failure.

ULTREX® Beats All Competitors

This comparison chart below is created by Stork Technimet Corporation an independent unbias testing facility. This test shows that Infinity from Marvin's ULTREX® Fiberglass far outperforms the competition in every category.

References: Stork Technimet/Testing Corporation: #0602-15293, #0512-14889, #0704-19702, #TCT006638P. Precision Measurements and Instruments Corporation: #13043-DS. Tecton: # ESP010521P, "Test Results for Fibrex and Ultrex®". Plastics Engineering Handbook of the Society of Plastics Industry, Inc. Fifth Edition. Andersen Fibrex Manual: "A High Performance, High Value Biofiber Polymer Composite Technology". Renewal By Andersen®: "Fibrex Material: A Better Alternative, A Better Window". LD = Longitudinal Direction * Highest rate of thermal conductivity shown. Test results range from .10 - .13 for vinyl/wood composite (Fibrex) and .09 - .12 for Ultrex®.



Let's now compare what happens with ULTREX® frames. ULTREX® expands and contracts almost the same as the glass. When the 4.6 glass heats up it expands toward the ULTREX® frame 4.0 which is strong as steel and unmovable. The result is a frame as strong as steel with a thin elegant design that provides more viewable glass.

This 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


Comparing ULTREX® Window Frames to Vinyl Window Frames. Sliding Doors and French doors require large amounts of heavy glass, your frames must stay true and be strong enough to support all that heavy glass. Southern California temperatures can start off at 40 degrees and reach up to 110 degrees on the same day.

Vinyl frames expand and contract bend and warp with the changing heat and cold temperatures of everyday conditions, potentially causing the vinyl to chip, peel, bend and fade making vinyl windows difficult to open and close and affecting they're all-around performance.


The glass expands at a rate of 4.6 the vinyl frames expand at a rate of 30 which is 652% more than the glass. So as the different materials expand at different rates the vinyl expands 652% more than the glass, the frames pull away from the glass which eventually will cause ceil failure in your windows, the argon gas leaks out and your windows are no longer energy efficient. Remember this happens every day they expand in the heat and contract in the cold with the daily temperature changes. In this engineer specification sheet above, you can see the different rates in which each material expands and contracts. ULTREX® Fiberglass outperforms all other materials hands down.

Compare Vinyl Vs ULTREX®

This photo is a competitor's new vinyl window frame photo before the installation. View the bad corner welds, the bulky frames, and the poor finish. This is something you clearly want to avoid.

Compare Wood & Aluminum Windows

Wood frames - They are very attractive but highly vulnerable to weather damage. They also need constant maintenance and upkeep. This makes them a costly option. Infinity windows capture the beautiful details and profiles of wood - without the maintenance.

Aluminum frames - These require less care than wood. They rarely need repainting and are stronger than wood. But they are not very energy efficient or attractive. Aluminum frames and Vinyl Frames are used in new construction homes because they are cheap for the contractor but they quickly lose their energy efficiency.

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