As Aluminum Prices Rise, Fabricators Are Looking to Composites

Fiber-reinforced Polyurethane: The High-Performing, Cost-Effective Alternative to Aluminum Inserts

For decades, aluminum has been the go-to material for structural and thermal reinforcement in PVC window systems, prized for its strength and durability. But that reliance is now being put to the test. As the industry evolves, market conditions shift and new materials emerge, aluminum’s long-held place in window assemblies is being re-evaluated. 

One reason is hard to ignore: aluminum prices have risen significantly compared to the previous year. 

As of late August 2026, aluminum is sitting at roughly $3,220 per tonne, which is approximately $600 higher than it was just a year ago. Behind the spike is a familiar mix of pressures: supply chain disruptions, rising energy costs tied to aluminum production, tight inventories and geopolitical factors that continue to create market volatility. 

These conditions are prompting building and construction organizations to evaluate alternative reinforcement materials. For PVC windows specifically, fabricators and architects are looking at composite substitutes, and finding success with fiber-reinforced thermal reinforcements. Products such as Deceuninck’s Innergy® Reinforcements demonstrate how this material technology can provide structural performance while addressing some of aluminum’s thermal limitations. 

Strength Without the Thermal Trade-Off

These reinforcements are made from advanced fiber-reinforced polyurethane and offer several technical advantages that make them a practical alternative to aluminum inserts, particularly in light of current market conditions. 

From a performance perspective, one of the material’s standout features is its ability to provide a robust thermal break within window and door systems. While aluminum provides the necessary structural strength, it is also highly conductive and can create unwanted thermal bridging that reduces the overall energy performance of a window system and potentially affects the building envelope. By comparison, fiber-reinforced polyurethane reinforcements are engineered to minimize thermal conductivity, effectively enhancing the insulating properties of the overall assembly. This can improve energy performance and help window and door systems support increasingly stringent energy efficiency requirements. In fact, reinforcements of this kind are virtually impermeable to the cold or heat they would realistically be exposed to in any real-world environment.  

Depending on the specific product and application, leading products can resist temperatures from -40° F to more than 200° F. In material-to-material comparisons, certain products can also provide thermal performance up to 700 times better than aluminum. 

These thermal reinforcements also reduce the risk of condensation within a window system by regulating temperature and minimizing cold spots. Because the material does not corrode like metal, it can also help prevent staining sometimes associated with metal reinforcements. 

While addressing the thermal shortcomings of aluminum, fiber-reinforced polyurethane reinforcements can also provide significant strength and structural reinforcement of metal, but with added durability. Well-engineered composite components resist permanent deformation from impacts or high wind loads, while aluminum components may be more susceptible to denting, bending, taking a permanent set and other forms of deformation. This performance can be attributed to the production process, which involves cross-linking continuous strands of glass fiber with polyurethane polymer resin in a heat-accelerated continuous chemical reaction process called pultrusion. This gives the material a metal-like stiffness that can offer 100% flexural memory, exhibit zero creep under structural loads, and possess up to a 7,500 Kilopounds per square inch (Kpsi) bending modulus. Simply put, the material is engineered to flex under load and return to its original shape rather than permanently deform. 

No Retooling Required

Leading fiber-reinforced components can be custom designed to integrate into a customer’s existing window systems, where they are engineered to insert easily into the hollow chambers of sashes and frames. While fiber-reinforced polyurethane is approximately 75% as strong as aluminum in a material-to-material comparison, reinforcement profiles can be engineered to achieve comparable structural strength by increasing the cross-section area of the component. This flexibility means fabricators do not have to undertake costly window system redesigns or retooling processes. 

This approach not only improves the energy efficiency and structural strength of the window, but also helps fabricators maintain their current production workflow while upgrading their product portfolio for customers. In an industry increasingly focused on production speed and product customization, this kind of integration flexibility can provide a meaningful operational advantage. It can also allow fabricators currently using aluminum inserts to respond to price volatility by evaluating higher performing materials without significantly disrupting production or redesigning their existing systems. 

A Smarter Bet in a Volatile Market

The rising costs and thermal inefficiency of aluminum are encouraging more fabricators to evaluate fiber-reinforced composite components. By considering alternatives to aluminum, fabricators can enhance the energy efficiency and structural integrity of their products while reducing their exposure to fluctuations in the aluminum market. Advances in materials, engineering and custom profile development have also made the transition increasingly practical for existing window and door systems. 

Fiber-reinforced polyurethane reinforcements are not simply a response to current aluminum prices. They represent a broader opportunity to combine structural performance, thermal efficiency and production flexibility within modern window and door systems.