Sternfenster has expanded its premium PVC-U window portfolio with the launch of Timberline, a next-generation flush sash system developed to answer growing demand for high-end heritage and contemporary installations. Designed to mirror the refined proportions of classic timber flush sash windows, Timberline focuses on authentic detailing, while adding manufacturing and performance upgrades that position it firmly in the premium category.

At the heart of the system is Timberline’s standout engineering feature: unique square-welded internal and external joints. Unlike conventional PVC-U flush sash windows that often use a 45-degree internal mitre, Timberline achieves a sharp, perfectly squared finish on both the inside and outside of the sash and frame. The result is a cleaner, more architectural aesthetic, one that strengthens the timber-alternative look while delivering the crisp geometry increasingly preferred by homeowners, designers, and specifiers.

Speaking on the launch, Nathan Court, Sternfenster’s Chief Sales Officer, describes Timberline as a major step forward in timber-alternative design, built directly around installer feedback. The goal was clear: deliver the craftsmanship and visual depth of timber, combined with the efficiency, consistency, and reliability of PVC-U. With the square weld presented as a genuine market differentiator, Timberline is positioned to set a new benchmark within the flush sash sector.

In terms of specification flexibility, Timberline is available in a wide range of foiled finishes, including heritage woodgrain effects, modern matt textures, and dual-colour combinations, allowing installers to suit both period properties and contemporary façades. Hardware options can also be tailored to match traditional styling or modern minimalism.

Performance is equally central to the Timberline proposition. The system achieves U-values as low as 1.2 W/m²K, supporting improved thermal efficiency, while also offering configurations designed to meet up-to-date security requirements, including PAS 24 options. Sternfenster also highlights production consistency and workflow advantages, with Timberline designed for smooth integration into its digital ecosystem, including EasyAdmin+ and EasySales.

With Timberline, Sternfenster gives fabricators and installers a flush sash window engineered for premium visual authenticity, strong technical performance, and modern production efficiency, supporting growth in both the heritage renovation market and high-end residential projects.