Compressed Earth Block Construction
Office Tornavida Design Type New Construction Role Concept · System Development Size 90 m² Location Hacıbektaş, Turkey Year 2018
The plan of this part time home for an elderly woman and her adult son – an accountant – is amenable to a variety of expected uses. The small town of Hacıbektaş is off the beaten track of sightseers in Cappadocia but is nonetheless a site of continuous, annual religious pilgrimage by Bektaşis and Alevis from throughout Asia Minor and the Balkans. In line with age-old Anatolian customs of misafirperverlik (hospitality), those with second homes in the town are routinely hosting friends, casual acquaintances, dervishes, dedes, and even strangers with whom they have mutual friends. Consequently, traditional notions of a living room and one's own bedroom are immaterial. Depending on the circumstance, anyone, including the primary occupants, can end up eating, sleeping, lounging, or working anywhere. The hierarchy of the spaces is therefore more important than their taxonomy.
For this reason, the inward-focused Roman domus and its gradations of public and private (and indoor and outdoor) space is taken as a model. The ātrium serves not only as a transition from the street to the inner home but as a space for informal, semi-public gatherings, almsgiving, and serving lokma. It is also the (symbolic) space of religious animal sacrifice, an integral ritual of pilgrimage.
Much of the winter, the son occupies the home on his own, and the space corresponding to the tablīnum serves, just as in the Roman paradigm, as a place for receiving clients. But it also serves as his bedroom when his mother is present and as a standalone guest room for more formal guests. Like those of the Ottoman sofa and sedir, the functions of the common room (trīclīnium) are versatile: it is a place to commune, to rest, to eat, to work, and even for guests to sleep. These functions may be moved out to the peristȳlium whenever the weather permits.
Hacıbektaş sits in a barren landscape characterized by bitter winters and by mild summers with a significant diurnal swing. Its year-round residents live hand-to-mouth, which is reflected in its unembellished, often dilapidated housing stock. A ubiquitous and time-tested tradition of earth block (adobe) construction is slowly being edged out by the less labor intensive (but not necessarily less expensive) concrete masonry unit. The second challenge of this project was to rethink the earthen construction techniques that are common in the area and create a more robust but simple, additive, integrated system that can still (mostly) be assembled by unskilled laborers and minimizes the use of expensive and unsustainable materials.
This task is made simpler by the fact that Hacıbektaş is not in a seismically active area. In the system developed, walls of unstabilized compressed earth block – the fabrication of which requires less labor and time than adobe – sit on a grade beam above a rubble trench foundation enveloped by vegetable fiber geotextile. The otherwise uninsulated exterior and interior walls – which are 45 and 30 centimeters thick, respectively – are breathable, have good insulating properties, and have high thermal mass. At intervals, stainless steel wire ladders are laid horizontally within the wall, and lightly reinforced internal lime "columns" provide vertical stability. The bottom few courses of block are stabilized with gypsum and lime (following the ALKER recipe developed at Istanbul Technical University) to increase the resistance of the base of the wall to water given that snow often accumulates in winter. Fired brick is only used to protect the base of the wall where it meets the grade beam. The exterior of the walls is finished with a three-coat lime render reinforced with hemp fiber, and the English Cross bond may selectively be left exposed on the interior.
A cork, clay, and lime floor slab sits atop a layer of insulating foam glass. Underfloor heating pipes are held in place and protected by clay mortar and topped with rammed earth which can, it turn, be polished. In the event of tremors from a faraway earthquake, the grade beam and walls are intended to roll around as a unit on top of the trench foundations. The floor slab would buckle under this lateral movement, so a generous expansion gap is left between it and the grade beam.
The ceiling and roof structure consists of low jack arches of compressed earth block supported by low profile IPE AAAA beams or tee sections and stabilized in the transverse direction by intermittent steel rods concealed within the arch as well as by a reinforced lime mortar slab. The steel beams, in turn, sit on a concrete ring beam within the block wall which also serves as the lintel at the doors. A continuous, gravel-lined channel runs adjacent to the parapet wall and forms the perimeter of the intensive green roof which can either be planted with self-perpetuating vegetation of used as a vegetable garden. The parapet is topped with a lightly reinforced lime bond beam into which vertical reinforcing in the walls is tied.
The spare, white front façade frames the fruit orchard that occupies the forecourt between the house and the street. While there is a mandatory easement all the sides and rear of the property, perimeter walls are permitted along the lot lines. For this reason, the ātrium and peristȳlium both have an "exterior" wall so that part of this easement can be reclaimed for the inner sanctum of the home. Earth block claustra screens span the gaps between these freestanding walls and the building itself, hinting at the oases that lay behind them.