The Winston Heritage Sliding Sash Window is an exclusive, groundbreaking design by Gowercroft Joinery. Already installed in several Grade II listed buildings, including Winston Churchill’s former residence, this product was shortlisted for the Build It Awards in the “Best Windows” category and is now part of Gowercroft’s multi award-winning heritage range.
It is ideal for period and listed properties that demand a high-performance window with a truly slim-lined, traditional appearance.
When working on heritage window replacements, a compromise is often needed. Conservation officers prioritise the historic character of the building, while homeowners want improved energy efficiency and lower maintenance costs.
Often, the compromise is to use slim double glazing. At first glance, this seems to suit both parties. However, slim double glazed units are not fit for purpose. They tend to degrade quickly, lose performance and develop condensation, compromising both appearance and effectiveness. The result is a lose-lose situation.
We have a strong reputation for working on heritage and listed buildings.
Often, we are asked to manufacture timber windows with slim double glazing. However, it goes against our values to sell a product we know will not last.
Instead of compromising, we looked for a better solution. Our product development team explored new materials and technologies. That led to the creation of the Winston Heritage Sliding Sash Window—a beautiful, durable solution that meets both conservation and performance needs.
The Winston combines traditional craftsmanship with state-of-the-art materials. It features:
Together, these innovations create a timber window that outperforms standard double glazing, even though it uses a glazing unit just 6.4mm thick.
Elegant design
The window includes slender 18mm glazing bars with an extended profile that reduces the visible width. Bars are applied both internally and externally to replicate traditional putty glazing. Classic ironmongery includes fitch fasteners and sash pulleys, and the windows are operated by a traditional lead-weight system.
Hidden performance
Our patented SashSealer system achieves Class 4 air permeability, the highest possible rating. All gaskets are hidden from view inside and out.
Superior energy efficiency
The Winston exceeds Part L Building Regulations for new builds. A typical window size of 1230mm by 1480mm delivers a whole window U-value below 1.35 W/m²K.
Long-lasting insulation
LandVac’s flexible edge-seal technology prevents gas leakage, ensuring consistent thermal performance. This is backed by Historic Scotland research that highlights the problems of gas loss in slim double glazing.
Zero-maintenance guarantee
The window comes with a full 10-year guarantee with no exclusions. It also qualifies for lifetime coverage under our TimbaCare programme.
Exceptional materials
Made using Accoya®, the world’s most durable timber. According to TRADA, Accoya is rated Class 1 for durability and offers a minimum 70-year service life.
Yes. The Winston Heritage Sliding Sash is part of our full Heritage Range. It pairs perfectly with the Richmond flush casement window and our Churchill Door, helping homeowners and architects create a unified look and consistent performance across the entire property.
We provide expert surveying, product demonstrations and factory tours at our Derbyshire workshop. If you’re working on a listed building, period home or conservation project and want windows that look authentic and perform like no other, contact us to arrange a consultation or visit. We serve customers across the whole of the UK.