The property is located in a mountain area near the Great Wall, north of Beijing.
Originally built in the middle of last century as underground storage for fruit trees for the village, the existing structure is built entirely of natural stone and consists of a rectangular volume of 21x11x4 meters.
The client owns a house on the south side of the property, in an elevated position overlooking the roof of the underground storage. The scope of the design was to extend the existing house by turning the storage into a 4 bedrooms residence.
The existing storage is constructed north facing, partially underground in a basin lower than the surrounding. To create a liveable environment for the new residence, a design solution for these particular conditions was required.
The design strategy focused on three main directions: enhance the identity of the storage and its stone walls, allow as much light as possible to the interior space and preserving the panoramic view from the existing house owned by the client.
The existing natural stone walls are preserved to a large extent and are fully exposed as a strong presence in the house in contrast with the new polished concrete structure and white plastered interior walls. Only in the north side the natural stone wall is replaced by a large glass façade and the soil removed to create a generous terrace in front, which occupies the entire length of the living and dining area in the inside. Also, in the north side, the garage is inset into the building as a wood cladded box.
In the open-plan living area, the custom-made open fireplace and the black kitchen counter set 2 focal points while the wood cladding of the garage provides a warm background to the soft seating area.
The new roof was designed to maximize the natural light input to the house. The existing roof was replaced by two concrete slabs, which are detached from the stone wall and set at two different heights. During the design stage we worked on many different options for the architectural volume of the house and consequently of the roof. The final solution convinced us as it was able to give to the house a modern design different from the neighbour houses yet very integrated with the natural surrounding. The roof in fact looks like two garden platforms floating above each other in perfect balance with the stone wall below as well as with the slope terrain that envelops the plot. The lower northern roof covers the living room and the garage and it is designed as a roof terrace. It is shorter than the existing stone wall length and creates two gardens in the east and in the west of the house. These gardens increase the natural of light from different angles.
The higher roof in the south is shifted to the west to allow a passage to the lower roof terrace and avoid to project shadow to the east courtyard.
The different heights of the roofs are responding to in the terraced degradation of the plot and the surrounding. The gap in between the 2 roofs allows more natural light to penetrate in the central part of the building and it is improving the natural ventilation during the warm seasons.
Below the higher roof in the south part of the new house are located the bedrooms. They enjoy a contemplative feeling thanks to their high ceilings and high-rise windows. Each room has a private bathroom. The bedrooms are connected by a passage which is elevated by three steps to the adjacent living area.
Next to the bedrooms, in the southeast corner, a tunnel connects the new house with to the existing residential building. As the belonging plots are separated by a side road, this passage passes through a tunnel under the road.
As a result, for the view from the terrace of the existing house is enriched by two floating green roofs in balance with the panoramic scene to the Great Wall.