INCA Case Study: Fore Street, North London

Saving space and staying sustainable in the city

It’s taken just 11 years for the world’s population to grow from seven billion to eight billion, meaning that land and space have never been more valuable than they are today.

This is especially true in major cities, including London, where developers and contractors are becoming increasingly keen to maximise existing space. One such developer is Riza Yelden, who owns a cluster of shops and apartments for rent on London’s bustling Fore Street.

In July 2022, Mr Yelden commissioned Zeki Construction to extend his three existing first-floor apartments – effectively doubling them in size – and add a second floor containing three new apartments. The project also involved building an extension on the back of the shop units to not only allow for the extension of the first-floor apartments but also to create a new cycle store, a bin store and new access stairs to the apartments.

However – like with most projects of this nature – while there were certainly opportunities to create more space using the existing building, such work was not without its challenges.

Being on a busy London street, there was a lack of storage space, and it was only possible to work within the footprint of the building. Access was restricted, and there was no electricity or water available on site, meaning hand machines were used to put in the screw piles for the lightweight steel frame system that was being used for the extension. 

The original structure of the building was traditional brick masonry, but it wouldn’t have been advisable to adopt the same approach for the extension work – not only because of the site limitations but also because it would have been more expensive, less sustainable, and would have involved considerable disruption to the shop units which had to continue trading.

Construction for this project was kept as environmentally friendly as possible, starting with the foundations. These were screw piles supporting a reinforced concrete raft slab, significantly reducing the volume of concrete, excavation depth and volume of muck away, as well as saving dozens of tonnes of embodied carbon in the process. The foundations were designed to bridge over existing services and to avoid disturbance and instability to the back of the shop units and all whilst maintaining fire escape access to the adjacent properties.

The screw piles and light gauge steel frame were designed, manufactured and installed by JPSE (John Plummer Sustainable Engineering). The light gauge steel also produced a considerable embodied carbon saving when compared to traditional construction methods. It is manufactured from recycled steel and fabricated offsite, then delivered in flatpack panels that weigh no more than 45kg, requiring no cranage or heavy plant.

This method of construction was ideal for saving space, as using traditional masonry would have meant going outside the building’s existing footprint. Using a light gauge steel frame with an External Wall Insulation (EWI) system not only maximises the internal space, but also speeds up the build process and increases the thermal efficiency of the wall.

Saint-Gobain Weber’s webertherm XM system was directly fixed to the lightweight metal structure provided by JPSE, using 150mm of mineral fibre (MFD) insulation offering a U-value of 0.17 W/m²K.

When it came to choosing the external façade, director of JPSE Barry Heyne recommended weberwall brick after using the product on similar projects. This was not only because of how little storage space would be needed for it on site, but also because he knew that Weber would be able to match weberwall brick in Antique Red Multi to blend into the texture and pattern of the LBC London Brick used in the existing structure.

Having used weberwall brick on other projects, he knew that the lightweight nature of the material is much more advantageous than using heavy masonry material. One wall wrap (displaying 20 brick faces) weighs the same as one standard brick.

It also generated less waste as – having retained all of the existing external walls – the frame was adapted to line up with what was left, and the Weber team could then calculate exactly how much weberwall brick was needed for the façade.

The external wall insulation system with weberwall brick finish was installed by the team at Thermoclad Ltd – a Milton Keynes-based contractor that specialises in EWI, render and cladding.   

The project was completed in October 2022 and Mr Yelden is currently pursuing planning permission to build a third floor which will also be constructed using light gauge steel.