Set on an unusual plot size in the vicinity of protected trees, the site constraints meant the design had to be non traditional in form and construction. The realised building is made of two wings connected by a central stair core using a concrete framework clad externally with a simple palette of charred timber, zinc and split slate. This simplicity in materials is carried through into the interior spaces with the same high attention to detail, using a warm but neutral palette.
The staircase is a key feature of the overall design, located in the central core and rising over three floors. It appears circular in shape but is, in fact, helical. This slightly unusual shape provides more space for the design to function and meets Building Regulation requirements, which stipulate the amount of turning space needed and the height and depth of each stair, which must be identical.
To present a sculptural feel, the staircase is cast in concrete that wraps around the inside of a curved concrete wall. The original interior design concepts featured limestone flooring throughout the ground floor, chosen to complement the planned limestone cladding to the exterior of the house with a polished stair. However, as the construction progressed, the limestone cladding was replaced with charred timber cladding, meaning that the planned limestone flooring would feel out of place in the building, so Clear Architects chose a polished concrete floor instead to maintain the restrained palette of materials. In this context, a polished concrete stair would risk the interiors feeling too clinical, so a different type of finish was sought.
A big factor influencing the form of the house is the 500-year-old oak tree located in the garden, formerly a part of Epping Forest. Using this as inspiration, designs were created to install a solid oak runner with prominent vertical posts acting as the balustrades. Creating a striking internal representation of the majestic tree’s form as well as complementing the vertical timber cladding on the exterior. Areas of the original planned, polished concrete remain visible to either side of the oak runners that have been laid on each tread. These areas are polished and sealed to give a low-sheen finish. The exposed concrete detailing is continued as a threshold at the top of each staircase and as a band around the carpet on the first- and second-floor landings.
As the structural width of the stair is over 1m, Clear Architects did not want to have a handrail along the inside of the curved concrete wall that the oak runner widths. The projection of the handrail and the oak skirting details were carefully considered to bring the effective stair width down to 990mm, allowing us to maintain the integrity of the curved concrete core wall rising through the building.
Creating the staircase involved a detailed process requiring skilled joinery and structural engineering to ensure the design was robust. One of the challenges of working with oak posts was creating the height needed for some of the balustrades. The 50 x 50mm solid oak timber pieces needed to reach heights of up to 7m. The recommended maximum length of post advised by the mill was 4m, beyond which structural integrity would decrease and, crucially, the propensity for warping would significantly increase.
Knowing that each individual piece could be no longer than 4m, Clear Architects explored how to join pieces to achieve the longer lengths needed to maintain the graceful curve across the three floors. To achieve this, the architecture firm designed the joins to stagger up the stairs, following the rise and emphasising the joins with negative rebates of 5mm. This creates slight shadow gaps where individual timbers join, giving the illusion of single pieces of oak from afar, but close up, the considered detail reveals itself.
The spacing of the 111 timber balusters was worked out by the creation of a 1:1-scale drawing template on plywood that was laid out on site and used to set out the posts as they were fitted.
All the oak pieces were given a stained finish, which is matched across the house in all timber elements, from the doors on the ground floor to any timber elements in joinery pieces throughout the house.
To maintain safety and avoid slipping, each oak tread has three brass trims, creating a nosing detail that contrasts beautifully with the stained oak. This brass detailing is carried throughout the property on handles, carpet edgings and hinges.
Another challenge was how to introduce borrowed light into the spaces leading off the stair core. The 2.7m-diameter rooflight at the top of the stair core floods the core itself with light, but getting this light to the landing areas on the first floor behind the curved wall was important to avoid it feeling dark and dingy in comparison.
This has been achieved by casting vertical slot openings into the concrete wall. These slots are of different sizes to accommodate the waist of the stair’s structure that follows the wall at that floor level. Mimicking the verticality of the external timber cladding, the slots allow light to filter through as well as provide a visual link to the stairs from the landing behind the wall.
The completed staircase at Wyvern House is a stunning feature at the centre of this beautiful property. It is a testament to what detailed design and vision can achieve and is a real talking point of this home.