The wooden roof was constructed to form a conservatory in this north-facing London garden that has strong afternoon light from the west on sunny days. Natural light within the built environment is appreciated and desirable in northern European climates, this being where the conservatory was originally invented.
Traditionally, conservatories tend to have a pitched roof, with glazed panes creating a fall for the rainwater to run off, which reduces watermarks on the glass and maintains good visibility to the sky. However, the traditional roof pitch requires height, which was not an option at the rear of this London semi detached Grade 2 listed house. Our solution was to create a series of higher pitches in short lengths that push rain water rapidly to the longer gentle primary valley fall. Consequently, the overall roof height was kept to a minimum, yet it has a well-drained glass surface with a deeper floor plate below.
The dia-grid geometry of the roof structure was derived simply from the existing site boundary, and helps to segment the Four Seasons glass roof into practical unit sizes. With the deep profiles within the grid, the beams cast palpable shadows of the dia-grid into the space and sometimes onto the beams themselves throughout the year, this emphasises the presence of natural light in this northern European climate.
Once the roof was formed, the dining space below was developed in relation to the garden, which is higher than the conservatory floor level. In order to mediate this topological condition, we inserted an 'empty stage' at table height between the garden and dining room. The primary purpose of the stage is to be 'empty' so that the garden merges into the background within a framed view. For the occupiers, the space below the roof feels as if it is expanding into the garden.
We took full advantage of the natural structural capacity and low thermal conductivity of wood. The entire conservatory, from the roof, to the window and door, was made from the same species of acetylated wood components, which is known for its durability and dimensional stability. From our digitally transferred design models, the wooden beams, posts and window frames were processed to within a millimeter of accuracy with a 5 axis CNC router. This enabled the planned roof falls to be installed correctly and easily on site which also minimised waste and off cuts. All of the cross junctions of the beams were structurally designed with no requirement of glue or any mechanical fixings (although glue was used for the ease of positioning during the assembly process).
Externally the wooden faces are fully exposed and charred to protect against rot and fungus decay and internally they were oiled so that it breaths. Both treatments allow the wood an extended longevity. The empty stage, adorned by a red maple tree, remains devoid of activity except for the occasional play of dappled light on the stone surface by the large European ash tree in the garden.