Replacement Steel – Framed Glazing in Hampstead Garden Suburb

This article was originally published in Listed Heritage Magazine. View the original article.

Hampstead Garden Suburb was designated as a Conservation Area in 1968. Internationally recognised as one of the nest examples of early twentieth century domestic architecture and town planning, the London Suburb was conceived by Henrietta Barnett as a model community of beautiful houses set in a verdant landscape and the properties within it were designed by some of the best architects of the day.

Front elevation of Arts & Crafts style house in Hampstead Garden Suburb fitted with new bespoke steel windows with leaded lights from the Clement Brooking range.

Today, the Suburb comprises around 5,000 properties, many of which are listed and is home to some 16,000 people. The Hampstead Garden Suburb Trust operates a management scheme which requires freeholders to get prior approval before altering the external appearance of their properties. This means that the Suburb survives relatively intact, reflecting the original vision of Barnett and master planner Raymond Unwin.

Many of the homes in Hampstead Garden Suburb are Arts and Crafts in style with original steel-framed windows and the Trust stipulates that replacement windows must be very similar to the originals. Clement Windows Group offers two window ranges which are suitable for these properties – Brooking, which was developed in conjunction with the Trust and other conservation bodies and takes its name from internationally renowned collector and architectural historian Charles Brooking, and EB20, an exceptionally slender, high specification steel window which replicates existing or original steel windows. Clement’s W20 steel profiles are also appropriate for replacement steel doors in this Conservation Area.

The stunning Arts and Crafts style house pictured above and below is located in Hampstead Garden Suburb and has recently been fitted with new leaded Brooking windows and W20 steel doors. The front and back elevations are very different yet the new windows provide just the look that the owner and Hampstead Garden Suburb Trust were seeking without detracting from the original character of the property.

The new windows and doors at the house flood the interior with natural light.

The new windows and doors are expertly engineered, thermally efficient units and the exceptionally slim frames allow the maximum amount of light to flood the interior. Both the windows and the doors were polyester powder painted RAL 9005 Jet Black. Homeowners selecting products from these ranges have the option of choosing dual colour where the frames can be painted one colour on the outside in line with conservation requirements and another on the inside to match an interior design scheme.

The owners of the property shown below also chose new steel windows from the Brooking range and W20 steel doors for the refurbishment of their property. The leaded light windows had unique handle plates and Clement made templates of the existing ones to ensure the new plates were as close to the originals as possible. The client commented: “It was very easy working with Clement once we’d made the decision to renew our metal windows. They took great care over the smaller details such as the handle finishes, window hinges and the special decorative detail behind the top floor window pulls. As a result, we have new up to date working windows that are fit for purpose, a pleasure to use and look at, and also comply with the Conservation Area and Listed Building requirements for this area.”

The new steel windows at this property were painted RAL 9016 Traffic White.

For each of these projects, work was carried out with the approval of Barnet Planning Department and the Hampstead Garden Suburb Trust.

Updating or altering a building in a Conservation Area can require the owner to apply for permission and securing this can be a lengthy process. Therefore, it is prudent to start discussions with the planning authority or to involve a conservation architect or heritage consultant as early in the process as possible.

Replacing steel windows in a Conservation Area may be necessary because the existing windows have deteriorated due to age or neglect and are no longer fit for purpose, or because there is a need to reduce the energy loss from the original frames. New steel windows might also be required when an extension is added to a building and the new fenestration needs to be similar to the rest of the windows and doors or to replace inappropriate plastic windows that were installed at an earlier, less regulated time.

We tend to think of steel windows as belonging to the mid-twentieth century. However, before the introduction of standardised rolled steel window sections at the end of the First World War, steel windows were already popular in domestic architecture, particularly as a result of the fashion for leaded light windows in the late nineteenth and first half of the twentieth century.

Today, the steel window replacement industry is dominated by hot rolled steel windows whose profiles are close in appearance to those which have existed in a similar form for more than 150 years. The look of a mild steel frame has not really changed since late Victorian times and the basic ‘Z’ pattern section used to create both fixed and opening lights remains universal.

There are fewer profiles available today and steel windows do vary significantly, but new steel profiles can – at high cost – be engineered to order which replicate even rare and unusual examples of historic fenestration.

Modern steel frames are hot dip galvanised to EN ISO BS:1461:2022, weather stripped and have a surface coating of polyester powder paint to BS 6497 2005 EN 13438 2018 applied. Subject to the historic significance of the property Conservation Officers might insist on single glazed replicas, but it is possible to produce double glazed insulated glass units which are very close to the look of traditional steel windows. These double glazed units will achieve energy preservation, security, reduction of sound and solar gain without detracting from the building’s appearance.

Clement made templates of the original handle back plates to ensure the new ones were similar.

For more information, contact us, we’d love to hear from you.