I have visited many traditional earthen towns, but Djenné in Mali is certainly one of the most interesting and well-preserved. Located in central Mali by the Bani River, Djenné is one of the oldest continuously inhabited towns of Sub-Saharan Africa with the earliest settlement dating to the 3rd century BCE. Djenné is known for its remarkable earth architecture and well-preserved urban fabric, for which the town was declared a UNESCO World Heritage site in 1988. Djenné is also home to one of the world’s most famous mosques, the Great Mosque of Djenné, which is also one of the world’s largest adobe or mud brick buildings.
Djenné’s World Heritage status is meant to preserve the characteristic architecture and urban fabric of the town, but local opinions are divided over the restrictions UNESCO poses. One of these restrictions is that the residents of Djenné are only allowed to build with earth and not with cement. The earth buildings of Djenné require annual maintenance which is a burden on the locals, many of whom think UNESCO shouldn’t restrict people’s lives or should at least support them financially. Lack of income from tourists due to years of instability and fighting in northern Mali makes it even harder to find the motivation to follow UNESCO’s guidelines.
Traditional earth architecture of Djenné
A typical house in Djenné has two stories, a flat roof, a courtyard and very little windows. Three main architectural styles are found in Djenné, namely Moroccan, Toucouleur and Sudanese. The Moroccan and Toucouleur style houses have many decorative elements, while the Sudanese style is more simple. All houses are built with adobe, or sun-dried earth bricks, locally known as ferey, and plastered with mud. Pieces of wood are commonly inserted into the walls between each five courses of bricks in order to make the houses stronger. Ceramic pipes are used to drain rainwater from the roof in a way that keeps the water from damaging the walls.
The main construction material, mud, comes from the floodplains of the river Bani at the edge of town. The site is under water for several months each year after the rainy season and the earth remains muddy even after the water starts to drain. The residents of Djenné take advantage of this by using the ready-made mud for construction, instead of digging dry earth and laboriously mixing it with water. The calcite-rich mud from this site makes very durable adobe bricks as well as mud mortar and plaster.
Construction work in Djenné follows the natural seasons with the peak construction season being March and April. Depending on how much it rained the previous year, it is generally possible to start making bricks in February when the floodwaters have mostly receded. Construction then continues until the end of the dry season in May, although in May the work becomes more laborious as the ground becomes harder and there is less water available on-site. The floods of the next rainy season flatten the holes that were created while digging the mud, preparing the site for the next construction season in a beautiful cycle of materials.
Annual maintenance of Djenné’s earth houses
The architectural style in Djenné leaves the earthen walls and roofs exposed to the rain. This is not a big issue in the semi-arid climate of central Mali, but it does mean that buildings need regular maintenance to keep them from melting away after consecutive rainy seasons. In particular, the exterior walls and roofs need to be replastered periodically, ideally every year.
The mud used for plastering is gathered from the site outside town and rice husks are mixed in to reduce cracking. After the mix is prepared, the mud is covered from the sun and left to settle for a few days. Plastering is generally done by a skilled mason who determines when the plaster is ready for use. More rice husks and water are added to the mixture right before use.
During my visit in early May most houses had been freshly plastered in preparation for the rainy season. The paradox was that the new plaster had a lot more cracks than the old one. The reason behind this is that the mud used is mainly clay with very little sand and clay shrinks significantly when drying, which causes cracking. When the rains start the clay gets wet and swells again so that the cracks are sealed. As the drying process becomes slower with frequent rains, by the end of the rainy season there are little or no cracks left. Hence the replastering is done before the rainy season.
The Great Mosque of Djenné
The most iconic building of Djenné is its Great Mosque. The first mosque at the site was built in the 13th century, but the current mosque (the third reconstruction) was built in 1906-1907. Just like Djenné’s other buildings, the mosque is built with adobe bricks, while the earthen roof is supported by a palm wood structure. The mosque is built on a raised on a platform in order to protect the building in case of flooding
The design of the Great Mosque of Djenné is full of religious symbolism. The interior of the mosque is dominated by 99 massive pillars that represent the 99 names of God. 105 skylights provide the interior with light and ventilation, with the number five representing the five daily prayers of Islam. Meanwhile, the minarets are topped with ostrich eggs that are symbols of fertility and purity in Mali.
The style of adobe bricks used in the construction of the mosque is different from what is used in Djenné today. These bricks were cylindrical and shaped by hand instead of using molds. This was the norm in Djenné until the colonial times in the 1920s when the residents of Djenné switched to rectangular, European-style bricks. The mixture was also different, with shea butter and leaves of baobab trees mixed in with the mud instead of today’s more economical rice husks.
The Great Mosque also requires annual maintenance to keep it from being destroyed by successive rainy seasons. Replastering the mosque has become an important annual festival that the whole town participates in. The festival generally takes place in April and the event is accompanied by food and music. Djenné’s four quarters are each responsible for preparing a set amount of mud plaster for the event. The mixture of mud and rice husks is prepared weeks in advance and left to settle for better results.
The whole community participates on the day of the plastering. Women carry water while men mix and bring baskets of mud to the masons. The plastering itself is done by skilled masons, and with around 40 masons the work can be finished in just half a day. Each mason has his own style and level of experience, which can result in variations. Palm wood projections function as permanent scaffolding in the higher parts of the mosque.
Burden of World Heritage status
UNESCO World Heritage status is meant to preserve the heritage of Djenné, but simple restrictions on what people can and can’t do have become a burden on the local people. Many residents of Djenné would like to use more modern materials or spatial layouts that are more suited to modern life, instead of feeling like a part of a museum. What Djenné needs is development that fits the traditional framework, but lack of finances, management and technical competence make it difficult to tackle the challenge of making the town fit for 21st century life.
According to my guide, around half the people of Djenné want to keep the earth houses while the other half would rather build with concrete. The locals know that earth houses are cooler in the summer and warmer in the winter, but the expense of replastering every year is so high that many would prefer to live in a concrete house instead. Even though the materials are local, the mason has to be paid, as well as the transport of the mud and the rice husks. Even finding rice husks is challenging because recent rice harvests have been low due to little rain. It is not difficult to see why some residents would rather spend more money on a cement house, or at least cement plaster, but this is not allowed by UNESCO.
Some people go around the rules by tiling their walls with fired clay tiles and cement mortar. This is allowed by UNESCO because the clay tiles are something traditional and locally made (although the tiles originally had completely different purposes, such as lining graves). But the masons of Djenné know that cement on earth walls is problematic and hence don’t recommend the use of tiles. When there is a crack and water gets in the earth wall, the cement doesn’t let the water dry out and the wet expanding earth wall causes more cracks. The Great Mosque of nearby Mopti was plastered with cement in 1978, and this incompatible plaster eventually led to the deterioration of the mosque due to water infiltrating the structure. The cement was eventually removed and mud plaster restored in a restoration project by the Aga Khan Trust for Culture.
UNESCO on the other hand seems to be more worried about the integrity and authenticity of the historic site than about the welfare of its residents. What UNESCO seems to have a hard time accepting is that earth architecture is not something static that lasts for hundreds of years. Earthen dwellings are periodically demolished and reconstructed, and at each reconstruction the design evolves with new ideas. Instead of conservation of individual buildings, the focus should be on preserving the knowledge and techniques of Djenné’s masons while promoting further experimentation with local materials. In this way, Djenné can develop its earth architecture into the 21st century and continue being a living town with a grand heritage, instead of one frozen in time.