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Astragal Bars vs. Plant-On Bars

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The image shows a grey Georgian-era two-storey building with large white-framed timber sash windows. Each window has multiple panes and features Gowercroft's innovative integrated conservation bars, blending seamlessly with the building's traditional design. The main door, also white, has an arched frame and is slightly raised from the ground. The overall appearance is clean and elegant, highlighting the well-preserved architectural details characteristic of the Georgian period.

Is there an alternative to plant-on bars or astragal bars for heritage windows?

Reading Time: 3 Minutes
Published on: July 24th, 2024

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Astragal Bars vs. Plant-On Bars: What’s Best for Heritage Windows?

When you want to preserve the historical integrity of heritage properties, choosing the right window bars is crucial. Understanding the differences between astragal bars and plant-on bars helps you make an informed decision. At Gowercroft Joinery, we combine traditional aesthetics with modern engineering to maintain both the look and efficiency of your windows.

Original Georgian Bars

Original Georgian bars in historic windows divide the glass into smaller panes and are an integral part of the window frame. These bars are essential for maintaining the traditional appearance of heritage properties.

What Are Astragal Bars?

Astragal bars in replacement historic windows replicate the look of original Georgian bars. These slim strips of wood or metal sit on the surface of a glass pane to make it look like the window is divided into smaller panes. For double or triple-glazed windows, additional bars between the panes enhance this effect. Today, astragal bars help historic buildings retain their old-fashioned look while updating windows for modern performance.

What Are Plant-On Astragal Bars?

Plant-on astragal bars attach directly to the glass surface, replicating the look of individual panes within a larger sheet of glass. Unlike traditional astragal bars, you apply plant-on bars after manufacturing.

Why Are Plant-On Astragal Bars Popular?

Plant-on astragal bars have gained popularity for several reasons:

  • Cost-Effective: They cost less to produce and install.
  • Easy to Install: You can easily add them to existing windows, making them ideal for upgrades.
  • Flexible in Design: You can customise them to meet specific architectural styles or personal tastes.

Common Problems with Plant-On Astragal Bars

Despite their benefits, plant-on astragal bars often encounter issues:

  • Adhesive Failures: The adhesive can fail, causing bars to detach.
  • Planning Permissions: They may not receive approval for listed buildings or conservation areas due to their non-permanent nature.
  • Maintenance Issues: Loose bars can increase maintenance and compromise the window’s appearance.
  • Visible Gaps: You can often see gaps between the panes, making it obvious they are not original.

Gowercroft’s Integrated Conservation Bars

Gowercroft Joinery has developed Integrated Conservation Bars to address these issues. Our bars are part of a mechanically fixed grid to the frame, ensuring durability and stability. The pre-painted grid reduces reflections and maintains an authentic look consistent with heritage properties.

A close-up shot of a white timber window frame with integrated conservation bars, focusing on the curved and intersecting design elements. The bars exhibit a smooth, polished finish, emphasising their quality and elegance.
A workshop scene showing several white timber window frames with integrated conservation bars hanging from hooks. The frames feature intricate, curved designs and are displayed in a neat arrangement, highlighting the detailed craftsmanship and quality of the integrated conservation bars.
A close-up view of white integrated conservation bars for timber windows. The image shows a detailed intersection of the bars, highlighting their precise construction and smooth finish.

Benefits of Integrated Conservation Bars

  • Enhanced Durability: Mechanical fixation provides a stronger, more permanent solution.
  • Authentic Aesthetics: Pre-painting ensures a uniform appearance, mimicking traditional craftsmanship.
  • Compatible with Vacuum Glazing: enabling the use of thin profile, high-performance glass and keeping the aesthetics of single glazing.

Real Conservation Project Example

One notable project is at Newton Park Farm, an 1840s model farm in South Derbyshire. This Grade II listed property was the first in the region to have vacuum glazed windows approved, blending heritage conservation with modern technology.

A beautifully renovated white brick house with well-maintained green lawn and blooming flower pots in the foreground. The house features Gowercroft Joinery's timber windows, including Winston Heritage Sliding Sash Windows and a Churchill Heritage Door. The windows and door seamlessly blend with the historical aesthetic of the property, showcasing a successful combination of heritage design and modern functionality.

Planning and Innovation at Newton Park Farm

Ben, the homeowner, shared: “This was the first time that vacuum glazing/our Heritage range was approved for Grade II listed in South Derbyshire—setting a precedent for the rest of the planning authority. They were initially nervous about the glazing bars, but you developed a different system.” This innovation helped secure planning approval, showcasing Gowercroft Joinery’s ability to meet stringent conservation standards while enhancing the property’s historical character.

A modern bathroom with a large freestanding bathtub positioned in front of a wide window. The window features white timber sash frames with integrated conservation bars, offering a clear view of a lush, green garden outside. Above the window is a patterned Roman blind with decorative trim, adding a touch of elegance to the space. To the right of the bathtub, a sleek chrome shower fixture is visible, and a small vase with white flowers sits on the windowsill.

Benefits of Gowercroft Joinery’s Heritage Range

Our Heritage Range offers advantages for listed buildings and conservation areas:

  • LandVac Vacuum Glass Innovation: Ensures superior thermal performance while preserving the visual authenticity of historic windows.
  • 98% Planning Pass Rate: Our high success rate with planning applications reflects our deep understanding of heritage requirements.
A close-up of a white brick wall with a single sash window featuring integrated conservation bars. The window is framed with a black lintel and sill, contrasting sharply with the white wall. Through the window, a vase with white flowers is visible, and the reflection of a cloudy sky can be seen in the glass. The window's traditional design enhances the classic aesthetic of the building's exterior.

Contact Us

To discuss your specific requirements and see our craftsmanship firsthand, please contact us to arrange a visit to our factory. We look forward to helping you find the perfect solution for your heritage property.