Hollaway Studio’s weathered steel extension complements 18th-century Kent house

Tell us about the project

Our clients, Ed and Rebecca, wanted to replace a small and ill-suited extension to their 18th-century grade II-listed home with a more complementary but, nevertheless, modern addition providing a kitchen, dining area and playroom.

The house sits within an Area of Outstanding Natural Beauty (AONB) near Canterbury in the Kent Downs, and the rust-coloured steel facades of the extension were inspired by stone found in the field beside the house, which contains iron ore deposits. They also match the tones of existing brick and tilework. A material that might ordinarily be thought of as industrial blends well with the rural context. Iron ore stone is used at the foot of the steel walls, and meadow grass grows all the way up to the concrete path around the extension, unifying the building and the landscape.

Faceted facades are oriented to exploit views of the surrounding countryside, and oversailed by a sculpted roof that shades the large picture windows. The roof is planted with sedum so that from the first floor, too, the extension seems to merge with its setting.

How was the planning process?

We work in the area a lot and have a track record of delivering high-quality architecture, which builds confidence within the planning department. Early on we met with the head of planning, the planning officer and a conservation officer, and explained how the extension’s scale, proportions and materiality responded to their context. Our clients were also eloquent about why they wanted to build in this way, and consent was subsequently granted.

How does the extension work with the existing house?

The original building has the traditional charms of a Kentish country home: low ceilings and cosy, protective rooms. But to live in such buildings better, it helps to have contrasting spaces. On cold winter nights the family can sit around the old inglenook fireplace, but in the morning come into the high-ceilinged, open-plan extension and enjoy all the light that comes in through large windows.

Existing houses are sometimes forgotten when extensions prove more convenient to live in, but we have created a route through the house that loops through both the old and new parts around the central stair, so the whole building is well used but in new ways.

How was the extension constructed?

With small projects, we always try to use local contractors and suppliers. The trick to achieving good quality is not to make the structure too complicated. Here we have an irregular plan and opted for a steel frame as it’s well suited to a building with complex angles. It's also efficient and capable of carrying the load of the sedum roof.  

The steel cladding was installed by the contractor, with whom we’ve worked for 20 years. To reduce costs, we bought mild steel instead of the more expensive Corten, which is supplied pre-weathered. Newly installed, it makes the building look like a spaceship, but it has quickly rusted as anticipated.

Tell us about the interior?

The kitchen is the focal point, with a central copper-clad island echoing the angles of the facade, and ‘soft’ plywood cabinets against the brick wall of the original house. The polished concrete floor works as an efficient thermal mass for the underfloor heating and unifies the space, flowing out through a large pivot door to the outside space. Polished concrete was also used to form benches that sit at opposite ends of the extension, framing the space. One provides seating at the dining table, while the other is a cushioned reading space set against a window.

What is the most sustainable feature?

The sedum roof has numerous benefits. It stops the sun from striking the roofing membrane, preserving its life. The vegetation provides habitat for the biodiverse species in the AONB, while also acting as a carbon store. And the soil slows rainwater percolation and reduces surface runoff. It also helps to regulate the house’s internal temperature, retaining moisture for cooling and acting as a thermal mass. High levels of airtightness also help to reduce energy consumption.

What was the greatest challenge?

Buildings of this age are often damp, with windows that need to be replaced and poor foundations that need to be underpinned when an extension is added. Once you start remedying defects it can be hard to know where to stop, so it’s important to agree with the clients what the parameters are. Here we have preserved some of the ‘warts’ of the existing building, which certainly appear more prominent when a new extension is added but also contribute to character. Striking the balance is always a compromise.  

What is your favourite moment in the finished building?

There are a number of highlights, including preserving the character of the original building and the effect of unconventional materials in the extension – particularly the weathered steel – as well as the experience of the landscape from the kitchen-diner.

In the past, we’ve often used large sliding doors to open out an extension to the landscape. But with the British weather, there are a limited number of days on which that is useful. Here, the combination of fixed windows and a single pivot door works well to provide views and connect inside and outside at a lower cost. It also makes space in the extension more useful. We particularly enjoy the way that each facet of the facade provides a different view through the framed picture windows, forming a ‘curated’ gallery: the meadow, the church, and the oak tree. It’s an approach we’ll use again.

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