Extending A Listed Building: The Glass Extension

Extending A Listed Building: The Glass Extension

As interior designers we are often working with clients who would like to extend their properties. When it comes to listed property, this can prove tricky. A potential solution to our client’s desires for more space, is the Glass Extension. The technology in glasswork has become so advanced that a rear or side return extension can be achieved using few other, visible materials. In this blog, we explain why it could be the answer to your extension frustrations and give your home the wow factor at the same time. Plus we share a few tips that have helped us along the way.

1. Minimal Interference with the Original Building

Glass extensions can be constructed in such a way that there is minimal contact with the original building itself. Clever framework that can be attached to the main building by little more than a piece of lead flashing, meaning that the extension is completely freestanding. This is a big plus for conservation authorities as the existing building is left in tact and, if the extension were to be removed in the future, there would be little sign of the extension having been present. Furthermore, the extension is an obvious, modern addition to the property and in stark contrast to the original. This is often preferred over a sympathetic or in keeping extension which can blur the lines between the original and extended parts.

2. Uninterrupted view of the Original Building

The transparent nature of glass means that this type of extension barely interrupts the view of the original building to which it is attached. Framework can be kept to a minimum and if the building is of particular importance, low iron glass can be specified to ensure that any blue or green tint is removed from the glass, therefore increasing its transparency.

The use of oversized doors can assist with this further so there is less visible framework and even less interruption with the original building. Oversized pivot doors look great and mean that the whole front of the extension can open up to the outside.

3. Consider Where to Propose your Extension

One of the main considerations will be what you want to achieve with the extension. Rear extensions are popular to make transitions between indoor and outdoor spaces and often lead off of kitchens at the rear of the house. Side extensions are helpful to make best use of otherwise wasted space. In our experience, if working with a listed building, it is helpful to try to utilise an existing doorway or sash window as an access route to the glass extension. Local authorities tend not to like new openings being created on the external areas of listed properties.

4. Pre Application – Be Flexible!

We have found it very beneficial to submit a few options for the conservation and planning authorities to consider at the pre application stage. Of course you can state your preferred option but showing some flexibility in the construction, roof shape and overall look of the extension can definitely assist with your chances of approval. If you can get an insight into the thoughts and concerns of the local authority at the pre app stage, you can be better prepared to answer and deal with the issues in the formal application.

5. General Benefits and Tips for a Glass Extension

– If you anticipate resistance from neighbours, you may be able to appease them and the authorities with a glass extension as it will have little to no impact on your neighbours ‘right to light’. The nature of a glass extension allows light to travel through it and therefore not reducing the light to your neighbours property.
– If you require cabinetry in your glass extension and are concerned about the appearance of cabinets against the glass, consider having the glass coated with a block colour of your choice to just above cabinetry level. It will hide the cabinetry and add a design element.
– Make sure that the extension that you are proposing is not disproportionate to the overall size of the existing property. This is particularly important with listed buildings or in conservation areas.
– Be clear on your energy efficiency ratings. Thermal glass can assist with protecting against heat loss and Solar glass against overheating in glass extensions. If your energy efficiency rating is low as a result of a proposed glass extension, consider offsetting with a highly energy efficient boiler.
– Check the most recent permitted development rules for your area. Although this will not stop you from requiring permission to extend a listed building, it could mean that planning consent will not be required in addition if your plans meet the criteria.


Our suggested suppliers for glass extensions similar to those featured above are IQ Glass, Glass Space, Cantifix and Glass UK.