Secondary Glazing for Victorian Properties

Victorian properties typically feature timber sash windows — either two-over-two, four-over-four, or six-over-six pane configurations with distinctive glazing bars. These windows are single-glazed and thermally poor, but they are also architecturally significant and often protected by conservation area designation or listed building status.

The Challenge of Victorian Windows

Victorian sash windows present several challenges for improvement. They are notoriously draughty — the timber frames shrink and expand with seasonal temperature changes, creating gaps around the sashes. They are single-glazed, losing heat rapidly in cold weather. And they provide almost no acoustic insulation, allowing traffic noise, voices and urban sounds to penetrate freely.

Replacing Victorian sash windows with uPVC double glazing would solve some of these problems but at the cost of the original character and, in listed buildings and conservation areas, would require planning consent that is unlikely to be granted.

Secondary Glazing — The Victorian Solution

Our balanced vertical sliding (BVS/TBVS) secondary glazing is specifically engineered to complement Victorian sash windows. It mirrors the vertical sliding action of the original window, sits discreetly within the window reveal, and is virtually invisible from outside the property. The original sash windows are preserved exactly as they are.

With 6.8mm acoustic laminate glass and a 150–200mm reveal-fixed air cavity, a Victorian property near a busy road can achieve up to 80% noise reduction — transforming road-facing rooms from noisy to genuinely quiet. Combined with Low-E glass for thermal performance, the draughts, condensation and heat loss that are characteristic of Victorian properties are dramatically reduced.

Georgian Bars and Glazing Patterns

Many Victorian sash windows feature Georgian bars dividing the sash into smaller panes. Our secondary glazing can be specified to align with the original glazing bar pattern, maintaining the visual character of the window while adding the secondary pane discreetly behind.

Conservation Areas and Listed Buildings

A large proportion of Victorian terraced properties are located in conservation areas, and many are individually listed. Secondary glazing is the recommended solution in both cases — installed internally, it does not alter the external appearance and does not require planning consent in most circumstances.