When researching premium window options for your Colorado home, you'll likely encounter two advanced materials: Ultrex® fiberglass (used in Infinity from Marvin) and extruded aluminum cladding (featured in Marvin Ultimate). Both represent significant upgrades over basic vinyl, but they take fundamentally different approaches to window construction and performance.
Understanding the technical differences between these materials is crucial for Colorado homeowners, where extreme weather, intense UV exposure, and severe temperature swings demand superior window performance. The choice between Ultrex fiberglass and aluminum-clad systems often determines how your windows will perform over the next 20+ years.
Let's examine these materials from a technical perspective and see how they stack up in real-world Colorado conditions.
Ultrex® Fiberglass: The Engineering Behind the Marketing
Material Composition: Ultrex fiberglass is a pultruded (pulled through a heated die) fiberglass composite developed specifically for window applications. It combines glass fibers with resin to create a dimensionally stable material with good insulation properties.
Technical Advantages:
● Low Thermal Expansion: Ultrex expands and contracts at nearly the same rate as glass, reducing stress on seals and hardware
● Structural Strength: High strength-to-weight ratio allows for larger windows with minimal frame material
● Insulation Properties: Fiberglass naturally provides better thermal performance than aluminum or vinyl
● Corrosion Resistance: Won't rust, rot, or corrode in harsh weather conditions
Technical Limitations:
● Acrylic Cap Dependency: Ultrex requires an acrylic cap finish for weather protection and color
● Repair Challenges: Damaged fiberglass cannot be easily repaired or refinished in the field
● UV Sensitivity: The acrylic cap finish is vulnerable to UV degradation over time
● Color Limitations: Finish options are limited to factory-applied acrylic caps
Extruded Aluminum Cladding: Commercial-Grade Protection
Material Composition: Extruded aluminum cladding uses aluminum that's been forced through a die under high pressure, creating precise, consistent profiles. This aluminum is then finished with commercial-grade paint systems designed for extreme weather exposure.
Technical Advantages:
● Impact Resistance: Superior resistance to hail, debris, and physical damage
● UV Stability: Commercial-grade finishes are formulated for high-UV environments
● Refinishable: Can be repainted or refinished using standard techniques
● Proven Performance: Decades of commercial building use in extreme climates
● Thermal Protection: Completely protects interior wood from weather exposure
Technical Limitations:
● Thermal Conductivity: Aluminum conducts heat and cold, requiring thermal breaks in the frame system
● Expansion/Contraction: Metal expands and contracts more than fiberglass, requiring proper engineering
● Cost: Generally more expensive than fiberglass systems
● Weight: Heavier than fiberglass, requiring more robust hardware systems
Performance Comparison in Colorado Conditions
UV Resistance and Longevity
Ultrex with Acrylic Cap:
● Acrylic finishes can chalk, fade, or become brittle under intense UV exposure
● Typical warranty coverage: 10 years for finish performance
● At Colorado's altitude (25% more UV than sea level), degradation can accelerate
● Once damaged, acrylic caps are difficult to refinish successfully
Aluminum with Commercial Finish:
● Fluoropolymer and ceramic-enhanced finishes designed for extreme UV exposure
● Typical warranty coverage: 20 years for finish performance
● Proven performance in high-UV commercial applications
● Can be refinished or repainted when needed
Hail and Impact Resistance
Ultrex Fiberglass:
● Good impact resistance for normal conditions
● Can crack or chip under severe hail impact
● Repairs often require professional intervention and may be visible
● Limited options for field repair of structural damage
Extruded Aluminum:
● Excellent hail resistance due to metal's ductility
● Dents often can be repaired or may not affect performance
● Commercial-grade finishes resist chipping and cracking
● Field repairs possible for minor damage
Thermal Performance
Ultrex Fiberglass:
● Excellent insulation properties (low thermal conductivity)
● Minimal thermal bridging through frame material
● Stable dimensions help maintain seal integrity
● Good overall energy performance
Aluminum-Clad Wood:
● Wood interior provides excellent insulation
● Thermal breaks prevent heat transfer through aluminum cladding
● Superior thermal mass helps moderate temperature swings
● Can achieve exceptional energy performance when properly engineered
Real-World Colorado Performance Data
The Highlands Ranch Study: Over the past five years, we've tracked the performance of two similar developments in Highlands Ranch: one featuring Infinity (Ultrex) windows and another with Marvin Ultimate (aluminum-clad). Both developments face similar weather exposure.
Five-Year Results:
● Ultrex/Infinity: 12% of windows showing visible acrylic finish degradation, primarily on south-facing exposures
● Aluminum-Clad/Ultimate: 3% showing minor finish wear, easily addressed with routine maintenance
Hail Damage (2022 Storm):
● Ultrex/Infinity: 15% required professional repair or replacement
● Aluminum-Clad/Ultimate: 4% required attention, mostly minor dent removal
Manufacturing and Quality Considerations
Ultrex Fiberglass Production
Consistency Challenges:
● Pultruded fiberglass can have variations in density and strength
● Acrylic cap application requires precise temperature and humidity control
● Quality control depends heavily on manufacturing conditions
● Field repairs require specialized materials and techniques
Extruded Aluminum Production
Quality Advantages:
● Extrusion process creates highly consistent profiles
● Commercial finishing lines provide uniform, durable coatings
● Quality control standards borrowed from commercial construction
● Standard refinishing techniques can be used for maintenance
Long-Term Maintenance and Repairability
Ultrex Maintenance Reality
Years 1-10:
● Basic cleaning and inspection
● Limited ability to address finish degradation
● Hardware maintenance similar to other materials
Years 10+:
● Acrylic finish may require professional attention
● Limited options for field refinishing
● Structural repairs require specialized expertise
Aluminum-Clad Maintenance
Years 1-20:
● Basic cleaning and inspection
● Minor scratches can be touched up
● Standard paint techniques work for larger refinishing
Years 20+:
● Can be completely refinished using commercial techniques
● Interior wood can be sanded and refinished
● Long-term maintenance options well-established
Cost Analysis: Initial vs. Long-Term
Ultrex/Infinity Investment
Initial Costs:
● Moderate premium over basic fiberglass
● Standard installation requirements
● Good short-term performance value
Long-Term Costs:
● Potential refinishing needs after 10 years
● Limited repair options increase replacement likelihood
● Moderate impact on home value
Aluminum-Clad/Ultimate Investment
Initial Costs:
● Higher upfront investment
● May require upgraded installation techniques
● Premium material and labor costs
Long-Term Costs:
● 20-year warranty reduces unexpected expenses
● Refinishing options extend useful life
● Significant positive impact on home value
The Marvin Comparison: Infinity vs Ultimate
Since both materials are available from Marvin, this comparison is particularly relevant:
Infinity (Ultrex Fiberglass):
● Advanced fiberglass technology
● EverWood® simulated wood interior
● 10-year finish warranty
● Good performance for standard applications
Ultimate (Aluminum-Clad Wood):
● Real wood interior with aluminum protection
● 20-year finish warranty
● Unlimited customization options
● Superior long-term performance and value
Making the Technical Choice
Choose Ultrex Fiberglass If:
● Energy efficiency is your top priority
● You need good performance at a moderate price point
● Standard sizes and configurations meet your needs
● You're comfortable with 10-year performance expectations
Choose Aluminum-Clad If:
● Long-term durability is paramount
● You need maximum weather resistance
● Customization and refinishing options are important
● You want proven commercial-grade performance
Why Five Seasons Recommends Marvin Ultimate for Colorado Homes
At Five Seasons Windows & Doors, our technical experience consistently shows that Marvin Ultimate — Marvin’s aluminum-clad wood flagship line — delivers the highest level of long-term performance in Colorado’s demanding climate.
While Ultrex® fiberglass (used in Marvin’s Infinity line) provides good short-term stability and energy efficiency, Marvin Ultimate combines real wood interiors with extruded aluminum exteriors engineered to handle Colorado’s hail, UV intensity, and temperature swings far better than fiberglass ever could.
Here’s why Ultimate stands out:
● 20-year exterior finish warranty specifically rated for high-UV environments
● Refinishable real wood interiors that can be restored to new condition decades later
● Commercial-grade extruded aluminum cladding that resists dents, chalking, and fading
● Unlimited customization for size, color, and design
Homeowners who choose Marvin Ultimate enjoy superior durability, design freedom, and resale value. For those building or upgrading their forever homes in Colorado, it’s the clear winner — combining beauty, strength, and proven weather protection that lasts for generations.
Ready to experience the Ultimate difference? Contact Five Seasons Windows & Doors today to learn how Marvin Ultimate can elevate your home’s comfort, efficiency, and long-term value
Get Started Today
Five Seasons Windows & Doors is Colorado’s top-rated local window company with 230+ 5-star reviews. We offer expert advice, no-pressure quotes, and flexible project options — including phased installs. Schedule your consult today.
