Types of glazing bars for historic sash windows: Lamb’s Tongue, Oval, and Royal Broken Lamb’s Tongue

Sash windows have been a defining architectural feature of historic and heritage buildings for centuries. The design, proportions and detailing are all critical elements of the windows that help contribute to the authenticity and aesthetic of the windows and period properties. Here we look at three different types of glazing bars, and the associated architectural eras and requirements.

Understanding glazing bars in sash windows

Glazing bars are the slender timber or metal elements that separate individual panes of glass within a sash window. The design evolved alongside advancements in glass-making and shifting architectural styles, making them a key indicator of a building’s historical period. When restoring or replacing sash windows in listed buildings, it is essential to match the glazing bar profile to the property’s era to maintain historical accuracy and meet conservation regulations.

Lamb’s Tongue Glazing Bar

Era: Georgian (1714 – 1837) & Early Victorian (1837 – 1860)

The Lamb’s Tongue glazing bar is a refined and elegant profile, characterised by a slender, curved moulding that ends in a point – getting its name from the resemblance to a lamb’s tongue. This profile became more popular during the Georgian period when large panes of glass were introduced, necessitating more delicate glazing bars to maintain visual harmony. The Lamb’s Tongue profile continued into the early Victorian period, often seen in townhouses, country homes, and formal buildings.

This type of glazing bar is best for: Grade I, II, and II* listed Georgian and early Victorian properties, where fine detailing is required to match existing architectural elements.

Oval glazing bar

Era: Late Georgian (1770 – 1837) & Victorian (1837 – 1901)

The Oval glazing bar features a rounded, symmetrical profile, creating a softer aesthetic compared to the angular look of the Lamb’s Tongue. This profile was frequently used in late Georgian and Victorian buildings, especially in more modest homes and provincial buildings where a simpler style was preferred.

This type of glazing bar is best for: Grade II and II* listed properties from the late 18^th to 19^th centuries, particularly those in provincial towns and smaller country estates.

Royal Broken Lamb’s Tongue glazing bar

Era: Regency (1811 – 1820) & High Victorian (1860 – 1901)

The Royal Broken Lamb’s Tongue is an ornate and highly decorative glazing bar profile that builds on the elegance of the standard Lamb’s Tongue with further detailing on the bar. This design became more popular during the Regency period and saw a revival in the High Victorian era when elaborate window designs were favoured in grander properties.

This type of glazing bar is best for: Grade I and II* Regency and High Victorian buildings, especially where windows are an integral part of the decorative façade.

Matching glazing bars to listed and heritage properties

For listed and conservation properties, choosing the correct glazing bar profile is essential to comply with planning and restoration guidelines. Please note that it is important to refer to documentation on the rules and regulations and liaise with industry professionals, as interpretations of guidelines can differ across the country. Here’s an overview of how these profiles align with different building grades:

• Grade I listed buildings: typically require exact historical replication, making the Royal Broken Lamb’s Tongue or finely detailed Lamb’s Tongue the best choices. 
• Grade II listed buildings: allow for some flexibility but should retain period-appropriate detailing, such as Oval bars for Victorian homes or Lamb’s Tongue for Georgian properties.
• Grade II* listed buildings: often necessitate accurate restoration using either Lamb’s Tongue or Oval profiles, depending on the building’s period.

Selecting the right glazing bar profile is crucial for maintaining the architectural authenticity of historic sash windows. Whether you are working on a Georgian townhouse, a Victorian villa, or a Regency mansion, using period-appropriate glazing bars – such as Lamb’s Tongue, Oval or Royal Broken Lamb’s Tongue – ensures compliance with conservation guidelines while also preserving the character of the heritage properties. As mentioned before, it is important to always consult with conservation officers or heritage specialists to ensure that any restoration work meets the necessary regulations and maintains the integrity of the building’s historical design.