Conservation Grade Double Glazing for Listed Buildings

Conservation Grade Double Glazing

Designed and made in house a Conservation Grade Double Glazed Unit (CDGU) mimics a traditional leaded light as closely as possible. We originally produced our CDG units in 2001 for a Grade I listed manor house in Dorset with approval from Historic England since then Sherriff Stained Glass have successfully fitted our units into many private residences in sensitive planning areas such as Dartmoor National Park and the New Forest.

How It works

Each Conservation Grade Double Glazing Unit has a stick-on lead applied to a specially made glass panel. Imperfections are introduced at the point of the making of the glass. This matches the effects of looking through a traditional leaded window.

We then solder the joints and patinate both the window lead and the boundary lead. This not only protects it but also helps to accurately mimic original leaded light.

The Conservation Grade Double Glazed Units are often inserted directly into your existing frames. This is a practical approach without the expense of replacing the framework itself.


The typical U-Values on windows is a measurement of heat loss and the rate at which it is lost.  U-Values indicate the overall performance in retaining heat and preventing it from escaping to the outside. U-Values are measured in Watts per square metre Kelvin, or W/m2 K. In simple terms, the lower the U-Value number, the better the thermal performance of the window.

·       A Stained and leaded glass window has a U value of 5.6u

·       A Conservation Grade Double Glazing Unit has a U value of 2.0u

·       A Triple Glazed Unit(TGU) has a U value of 0.7u

Planning Permission For Listed Building Windows

You may need to seek planning permission from your local conservation officer to install double glazing for listed buildings, grade I or grade II. It may also be necessary if you live in a conservation area.

We have the experience and knowledge in helping you to gain the necessary permission to upgrade your existing leaded windows. We have been successful in installing our conservation grade double-glazing windows in many areas. Our highlights include listed buildings in the prestigious St Georges Hill area of Weybridge. We have also completed projects in the idyllic New Forest and the Dartmoor National Park.

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Contact us

For further information about our range of products and services, call us on 01202 882208 or complete the enquiry form.

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