Want to Extend or Renovate a Historic or Listed Building?

A frameless glass link

The Link Between New and Old

Renovating a historic or listed building to incorporate new, modern elements is a popular trend within the architectural landscape. Whether replacing original windows or extending, the integrity of the original building is carefully considered in order to modernise the property whilst creating a contrast to its original structure.


Window glazing

Double height glass extension to Grade II* listed home in London
Credit Seacon Ltd.

IQ Glass can offer slim double glazed units which serve as brilliant replacement units for historic and conservation properties, greatly increasing their thermal and efficiency performance.

Our slim glazing units are double glazed glass units with a unit thickness of just 10-12mm. Using this system we are able to effectively and invisibly upgrade thermally inefficient, old and cracked single glazed units with a double glazed system, achieving u-values which surpass the Building Regulations thermal efficiency targets.

The glass panels consist of two panes of 4mm glass, the inner pane applied with low-e coatings to increase thermal efficiency, an inert gas filling and warm edge spacer technology. The gas used in these units is generally a mixture of Krypton and Xenon. These gases are heavier than the standard Argon gas filling which is used in most double glazed units and are perfect for this small cavity opening. The heavier gas along with the small cavity spacer means that no convection currents can form in the internal gas filling and cavity, resulting in less heat loss to the external faces.

IQ Glass Listed Property Glass LinkThe glass units look like single glazing from any distance, thus not changing the outward appearance of an old or listed property. But using this glazing solution gives you U Values from as little as 1.2 W/m2K compared with the typical 5.4 W/m2K in a single glass panel.

These slim units are extremely suitable for replacing glass in traditional Georgian sash windows, able to fit into a rebate of only 7mm, and have been acclaimed by Kevin McCloud for their ability to both thermally enhance historic buildings whilst keeping the design integrity of the original structure in place.


Structural glazing
Glass can be engineered to have many enhanced properties but is naturally transparent. This is the reason it is used to great extent as a bridge between what was and what will be.

It is often a requirement of the planning permission that any structure linking from a listed building to a new structure be transparent and frameless, but even if it is not, that clear definition in the structure and design of the building can allow you to do something different, new and contrasting without impeding on the classic architecture of the existing building.



Structural glass link on listed cottageIQ Glass, as specialist glaziers in frameless structural assemblies, have been called upon to provide just that many times over the years. One of the most notable would be the RIBA award-winning property by Found Associates. The country cottage based in the rolling greenery of the Cotswolds in a picturesque lakeside setting was given a complete re-haul and extension. IQ’s Minimal Windows were used throughout but the connection between the old and the new was a frameless, colourless, almost invisible glass link. Supported by the stonework of the new and original buildings the glass link space provides a clear break in materials making the extension seem almost as if they were freestanding, individual buildings.


Edge House

Frameless Glass Link with Integrated DoorAnother example of this invisible glasswork would be at this large residence, the link here was to connect the main house with a games and entertainment space. The invisibility of the frameless glass construction was made possible with the use of low iron glass, keeping the visual feel of the original structure and design. The structural glass link has a modular look, giving the illusion of having been manufactured off-site and simply put in place. This was achieved by highly technical installation work which creates an effortless finish.


Yew Tree House

minimal sliding doors into a glass box extension to a listed home. This cottage was both listed and in a conservation area, making the design and approval process incredibly technical. IQ utilised the vast knowledge and experience working on heritage buildings to gain approval for a ‘transparent’ structure. The minimal windows have a frame of 21mm, perfectly in keeping with the frames of the structural glass walls surrounding them. In keeping with the transparent structure and sleek design, where an inward-facing aluminium casement door was installed, the glass within the door was stepped over the doors framing. The result was a completely glazed, sleek exterior.


Contact IQ Glass today on hello@iqglass.com to discuss your listed or heritage project.


Glass extension to a grade II listed house


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Carly Coren

Carly is an integral part of the marketing team at IQ. She studied marketing at university before putting her knowledge into practice within the glazing industry. You will find her working on social media campaigns or writing blog content for the brand.