Achieving authenticity in PVC-U sash windows

In a demanding market, Mike Bygrave of Roseview Windows explains how to achieve true heritage authenticity in modern sash windows

Manufacturers of PVC-U sash windows often tout “authentic features” as a key selling point. They hope to replicate the classic style of traditional sash windows with one-off headline features such as run-through sash horns, narrower midrails or mechanical or faux-mechanical joints.

While individual features can improve a standard PVC-U sash window, true authenticity extends beyond that. It seamlessly combines traditional details so that they work together to create a modern, high-performance window that truly captures the essence of period sash windows. Roseview’s Ultimate Rose window exemplifies this approach.

The pitfall of piecemeal design

Sash windows are deep-rooted in British architecture; their appeal lies in their traditional aesthetics. Generally, PVC-U manufacturers try to capture this with a fragmented approach – adding features one-by-one, in isolation.

While this approach is easier, it only takes you so far. A heritage-grade window is more than a set of individual parts; everything has to work together as a cohesive whole. That’s the difference between traditional-style and genuinely traditional.

Heritage authenticity requires a deep understanding of the design and functionality of original sash windows. The traditional craftsmanship, proportions and details that go into them must be meticulously recreated. Moreover, each element should be carefully designed to complement all the others. 

Why? Because homeowners can tell the difference. When comparing a standard PVC-U sash window to an authentic one, initially homeowners will see the similarities. But very soon the differences become clear, and they realise that one replicates a timber sash window, while the other looks like a PVC-U window with added extras.

Ultimate Rose: more than a sum of its parts

Ultimate Rose is testament to the principle that true authenticity is more than a sum of its parts. Every element is intentionally designed to work together to create a window that is virtually indistinguishable from timber, no matter how close to it you get.

For instance, Ultimate Rose uses ultra-slim putty-line profiles throughout. Its seamless 35mm external midrail is complemented by the 44mm internal sash, resulting in a well-proportioned 9mm recess instead of an awkward step between two profiles with very different widths. This mirrors the delicate proportions of traditional timber sash windows.

Crucially, the profiles are combined using genuine mechanical joints, rather than the mitred or hidden welds commonly found elsewhere. True mechanical joints replicate the construction methods of original sash windows, but only when oriented properly with vertical joints on the sashes and horizontal joints on the frame. 

Harmonious design

The intentional design of Ultimate Rose ensures that everything works together harmoniously. Chamber fillers cover the tell-tale external balance chambers, giving a smooth, solid timber-like finish. Removable staff beads work with the window’s tilt function and sit neatly on top of the 50mm deep cill, giving a fitter-friendly flush face that’s easy to trim or architrave. Seamless run-through horns come in various designs, because original sash windows have different horn styles. Simple square-edged profiles and putty-line sightlines match the look of timber, especially when fitted behind the brickwork in a check reveal.

Individually each of these features is a step towards authenticity. But when designed to work together they become more than a sum of their parts, creating a window where everything (not just some things) is right. 

A planned approach

The success of Ultimate Rose underscores the importance of a bottom-up approach to design and authenticity. Focusing on how each element works together is an essential part of creating a cohesive, authentic modern equivalent of a traditional sash window.

Homeowners choose sash windows because they are the correct choice for their homes, despite lower cost casements being an option. They want authentic sash windows that capture the true essence of period design while delivering modern performance and ease-of-use. Ultimate Rose delivers exactly that.

www.roseview.co.uk