Ksar, kasbah, tighremt: the earthen architecture of southern Morocco

Images of ochre ksour at the foot of the Atlas have travelled the world, mostly through cinema. They say little about what these buildings are: a coherent constructive, social and climatic system, threatened today less by time than by the departure of those who maintained it. This guide defines the three types, describes how and why they are built, draws on UNESCO’s assessment of Aït-Ben-Haddou and on recent research into earthen renders, and says what restoring an earthen building involves today. It belongs to the typologies of the Moroccan architecture pillar.

Ksar, kasbah, tighremt: what are we talking about?

UNESCO describes Aït-Ben-Haddou as “a mainly collective grouping of dwellings” where, “inside the defensive walls which are reinforced by angle towers and pierced with a baffle gate, houses crowd together – some modest, others resembling small urban castles with their high angle towers and upper sections decorated with motifs in clay brick”. Those “small urban castles” are the kasbahs and tighremts housed inside the ksar. The community areas “include a mosque, a public square, grain threshing areas outside the ramparts, a fortification and a loft at the top of the village, an caravanserai, two cemeteries (Muslim and Jewish) and the Sanctuary of the Saint Sidi Ali or Amer”.

Where is this architecture found?

Aït-Ben-Haddou, “located in the foothills on the southern slopes of the High Atlas in the Province of Ouarzazate”, is “the most famous ksar in the Ounila Valley” and “an eminent example of a ksar in southern Morocco illustrating the main types of earthen constructions that may be observed dating from the 17th century in the valleys of Dra, Todgha, Dadès and Souss”. Its position is explained by trade: the site “was also one of the many trading posts on the commercial route linking ancient Sudan to Marrakesh by the Dra Valley and the Tizi-n’Telouet Pass”. Ksour line the oases and the routes; their wall protects harvests and people, and their collective granary, the agadir, keeps the community’s reserves.

UNESCO notes that “the oldest constructions do not appear to be earlier than the 17th century, although their structure and technique were propagated from a very early period in the valleys of southern Morocco”. Raw earth is not dated like stone: a maintained rammed-earth wall is rebuilt in layers, and living buildings are rarely of one period.

How are they built?

Load-bearing walls are rammed earth: damp earth compacted in layers inside a timber formwork, rising in successive lifts, 50 cm thick or more, which gives the ground floors their thermal mass. The upper parts, towers and top storeys, are sun-dried earth bricks, lighter and easier to decorate: the geometric motifs “in clay brick” that UNESCO notes under the cornices are bricks laid proud or recessed. Floors rest on palm, tamarisk or poplar beams covered with reeds and beaten earth. Openings are small, for coolness and defence.

Aït-Ben-Haddou’s authenticity rests on the fact that “the construction materials used still remain earth and wood”. UNESCO records that “the inclination to introduce cement has so far been unsuccessful, thanks to the continued monitoring of the ‘Comité de contrôle des infractions’ (Rural Community, Town Planning Division, Urban Agency, CERKAS). Only a few lintels and reinforced concrete escaped its vigilance, but they have been hidden by earthen rendering. Particular attention is also paid to doors and windows giving on to the lanes, to ensure that the wood is not replaced by metal”. The guide on rammed earth details the material and its upkeep.

Why does this architecture suit the climate?

UNESCO judges that “the earthen constructions are perfectly adapted to the climatic conditions and are in harmony with the natural and social environment”. Materials research says why: earth “gives the opportunity to build high living comfort structures, thanks to its breathability and thermal insulation”, it “is widely available in nature at an extremely low price”, is used “without the necessity of special transformations” and “requires a reduced energy amount for its processing”. Rammed-earth walls store the day’s heat and release it at night; covered lanes and narrow courts stay in shade; the ksar’s compactness reduces exposed surfaces. The “compact grouping, closed and suspended”, in UNESCO’s words, is a climate machine before it is a backdrop.

Why is this habitat vulnerable?

Criterion (v) of the inscription concerns “the traditional earthen habitat, representing the culture of southern Morocco, which has become vulnerable as a result of irreversible socio-economic and cultural changes”. UNESCO is precise about the mechanism: “the earthen buildings are very vulnerable due to lack of maintenance and regular repair resulting from the abandonment of the ksar by its inhabitants”. Research confirms that “the only drawback of these architectures is the limited durability of the material against the aggressive action exerted by external agents (such as rainwater, capillary rise, erosion, wind, anthropic action) that makes it necessary a constant maintenance”.

The cycle is well known: families leave the ksar for modern houses by the road, the render is no longer redone after the rains, water seeps in at the top of the walls and at the base, the timber floors rot, and the building collapses from top to bottom. At Aït-Ben-Haddou “the large houses in the lower part of the village, with well conserved decorative motifs, are regularly maintained”; elsewhere, hundreds of ksour and kasbahs no longer are.

What do you need to know to restore or build in earth today?

For inscribed sites, “protection measures essentially relate to the different laws for the listing of historic monuments and sites, in particular the Law 22-80 concerning Moroccan heritage”, and CERKAS, the Centre for the conservation and rehabilitation of the architectural heritage of Atlas and sub-Atlas zones, “ensures coordination in the implementation” of the management plan. Outside listed sites, the ordinary building permit applies to any construction, earthen or not; in rural settlements covered by a development plan, “obtaining prior authorisation is required for any construction”, as the guide on planning documents explains.

Technically, the lesson of conservation sites and laboratories is constant: a cement render on an earth wall traps moisture and bursts the wall from inside; earth must breathe. The Italian-Moroccan study by Mattone, Ibnoussina and colleagues, which tested earthen renders from the Marrakesh region stabilised with products “easily available on the Moroccan territory”, lime and gypsum, concludes that “with regard to water resistance, the addition of lime gives the best results”, that the plain earth render “has not withstood the test” of erosion, that gypsum reduces capillary absorption while lime increases it, that straw “generally worsens the behaviour” for adhesion, and that “the permeability to water vapour keeps almost unchanged in all the plasters”. In other words, the skin of an earth wall can be hardened against rain without stopping it breathing, provided lime or gypsum is used rather than cement.