Choosing windows and doors for listed properties isn’t just about historic aesthetics, they also have to create a comfortable living environment and preserve the building for the future.
We developed our award winning Heritage Range specifically to address the unique challenges and planning requirements associated with Grade I and Grade II listed buildings. From glazing bar innovations to thoughtfully designed finishing touches, our heritage windows and doors offer a solution that respects architectural history while achieving modern performance.
Here’s how we do it:
Why Use Vacuum Glazing in Listed Buildings?
Single glazing is original to most listed properties, but it lacks thermal efficiency, allowing substantial heat loss, condensation issues, and higher energy costs.
Whilst nobody wants to live in a constant draught or pay more for heating, upgrading glazing on listed buildings is a bit of a balancing act.
It is a common myth that you cannot have double glazing in a listed building. Whilst not strictly true, this rumour exists for good reason: glazing options should closely resemble what was there originally.
Glazing suitability for listed properties:
Standard Double Glazing: Provides better insulation but requires thicker frames, which don’t align with historic aesthetics and are often unsuitable for listed properties. There is also a noticeable double reflection that differentiates it from single glazing.
Triple Glazing: Highly insulating but unsuitable for heritage windows due to its bulk, which alters the window’s look.
Slim Profile Double Glazing: Designed to blend better with historic frames, but slim double glazing has durability issues. The narrow edge seals are prone to failure, especially in varied temperatures, compromising the unit’s lifespan. This risk meant we couldn’t offer our 10-year no-maintenance warranty on slim double glazing. The thickness, though reduced, may still appear out of place in heritage settings.
Why Vacuum Glazing is the Best Choice for Listed Buildings
We developed our heritage range with vacuum glass to retain historic charm without compromising performance.
Visually, the 8.3mm thick LandVac glass has a miniscule 0.3mm vacuum gap, which maintains the traditional appearance and prevents the double reflection common in standard double glazing.
With a U-value of 0.4 W/m²K, it provides excellent insulation, far superior to single glazing and beating most double glazing too.
Additionally, its warm-edge spacer seal resists the seal failures often seen in slim double glazing, allowing us to offer the 10-year no-maintenance warranty. Vacuum glass thus provides the ideal blend of durability, insulation, and authentic visual appeal for listed properties.
Why Are Glazing Bars So Important for Heritage Windows?
When replicating the look of historic windows, glazing bars play a critical role. Traditional pass-through bars replicate the original style, but modern alternatives like plant-on bars and astragal bars often fail to meet conservation standards. Here’s a breakdown of why each falls short and how we developed an innovative solution.
Why Don’t We Use Pass-Through Bars for Listed Building Windows?
Pass-through bars, where individual panes are separated by bars, are historically accurate but not ideal for modern glazing:
- Structural Challenges: Retaining original pass through glazing bars is incompatible with efficient glazing. Using pass-through bars to support the weight of vacuum glass would require much thicker bars, which would alter the original, delicate appearance of the window design.
- Reduced Efficiency: Smaller panes with multiple edges increase thermal bridges, allowing heat to escape more easily and reducing energy efficiency.
What Are the Problems with Plant-On Bars?
Plant-on bars adhere directly to the glass but come with their own issues:
- Durability Issues: Over time, plant-on bars can detach, especially in high-exposure areas.
- Inauthentic Look: These bars often appear flat and lack the depth and detailing that conservation officers look for in authentic restorations.
Why Aren’t Astragal Bars the Best Choice for Heritage Windows?
Astragal bars, which overlay the glass, provide a faux multi-pane look but don’t fully replicate historical authenticity:
- Lack of Depth: Astragal bars look “stuck-on” rather than integrated, missing the aesthetic detail essential for listed properties.
- Potential Durability Issues: Although sturdier than plant-on bars, astragal bars are still not as robust as a fully integrated option.
What Makes Our Integrated Glazing Bars Ideal for Listed Properties?
To address these issues, Gowercroft’s product development team created integrated conservation bars. These bars are fixed directly into the window structure, offering the authentic look of individual panes without sacrificing durability or energy efficiency. Conservation officers have particularly appreciated this solution on projects like Newton Park Farm, where maintaining historical integrity was essential.
Our finishing process for glazing bars has also impressed planners. Each window is painted as a single unit, creating a seamless appearance that hides the gaps between bars and panes. This meticulous finish means the window closely resembles traditional designs, making it difficult to spot any differences unless you are particularly looking for them.
Additional Features to Enhance Historical Accuracy
To meet the exacting standards of listed properties, we’ve refined several design elements:
- Putty Profile: Externally, we use a putty profile that replicates traditional putty glazing, preserving an authentic appearance.
- Elongated Bead Profiles: Internally, our deep, tapered bead profiles are more faithful to historic window aesthetics than standard designs.
- Unified Paint Finish: Each window is painted as a single unit, closely mimicking the look of original historic windows. This finish ensures a seamless appearance, making it hard to detect any separation between bars and glass.
Through these thoughtful adjustments, Gowercroft’s Heritage Range combines historical accuracy with the durability and thermal performance required for today’s listed building projects.
How Does Our Ironmongery Maintain Heritage Aesthetics While Ensuring Security?
Our casement windows are equipped with authentic butt hinges and casement stays for a traditional look, while hidden multi-point locking systems meet modern security standards without compromising appearance.
How Do Our Sliding Sash Windows Combine Heritage Style with Modern Benefits?
Our two sliding sash window options offer both traditional aesthetics and practical advantages.
The first style uses classic lead weights and marine-grade nylon cords, enhancing durability while maintaining a heritage look.
The second option incorporates a concealed spiral balance system, allowing for smooth, one-handed operation, even with large, heavy sashes. This system not only improves ease of use but also ensures a discreet appearance that preserves the window’s historical integrity while meeting today’s functionality standards.
Another defining detail is our fully concealed gaskets, which are completely hidden when the windows are closed. This ensures a smooth, uninterrupted look, free from the unsightly brush piles you often see on other designs—a detail that makes all the difference in maintaining a true heritage aesthetic.
What Makes Our Heritage Range so Durable?
Timber choice significantly impacts the lifespan and authenticity of heritage windows. We use Accoya, a high-performance timber with a 60+ year lifespan, chosen for its stability, sustainability, and minimal maintenance needs. Accoya’s durability is particularly suited to listed buildings, as it preserves the window’s appearance and structure over time. For the perfect durability pairing, we coat Accoya with microporous paint that resists cracking and peeling, reducing maintenance needs.
Can You Add Trickle Vents to Heritage Windows?
Yes, we offer fully concealed trickle vents as an option for increased ventilation, even though they’re not required by building regulations for heritage windows. Because they are hidden, this feature provides the benefits of ventilation without compromising the authentic appearance and becoming a problem for planning.
Real-World Success Stories: How Our Heritage Windows Fit Listed Buildings
Templeton House: We developed our Heritage Range specifically for Templeton House, our first large-scale project with rigorous heritage requirements. As Winston Churchill’s former residence, the property demanded an approach that preserved its historic character while meeting modern performance standards.
This project also marked our pioneering use of vacuum glass for window replacements—a relatively unknown technology at the time. Inspired by this landmark project, we named all our products in the Heritage Range, including the Winston sliding sash windows, to honour the legacy of historic properties like Templeton House. This installation set a new standard for our work on listed buildings, blending heritage aesthetics with cutting-edge performance.
Achieving PassivHaus standards in a heritage setting required precision.
Our heritage windows met both energy and conservation requirements, making them ideal for this project.
Slim-profile windows combined with advanced vacuum glazing allowed us to secure planning approval for this project, balancing energy needs with a classic look.
The striking blue frames add a bold, unique aesthetic to the property, enhancing its traditional charm while subtly modernising its appearance.
Why Choose Gowercroft for Your Heritage Project?
With our Heritage Range, Gowercroft offers a unique solution that satisfies both conservation officers and homeowners. By prioritising historical authenticity and modern functionality, we’ve developed windows and doors that blend seamlessly into listed properties, from the glazing bars to the finishing touches. Our innovations in design and material choice ensure compliance with planning requirements while providing durable, energy-efficient solutions for your Grade II listed property.
Experience the Quality for Yourself
Want to see how our heritage windows and doors fit into your listed property? Contact us today to discuss your project or book a factory visit to witness the Gowercroft quality first hand.