EARTH IN THE CITY

Arguably the most extensively used building material over time and across cultures, raw earth has been found expedient for building construction by ancient civilizations due to its ready availability and easy maneuverability. The current trend of ‘return to earth’ is ironically championed by industrialized / developed nations, France in particular. This is because current research has found the material to be viable economically, and technically. It also allows for a decentralization of the construction industry, thus empowering more individuals with the ability to directly meet their own housing needs.

Adoption of raw earth technology provides a broad spectrum of opportunities for national development. The local availability of the basic raw materials and skilled / unskilled labour cuts down effectively on the cost of importation of services and materials which have been a significant drawback for the construction industry in developing countries. This draw back particularly affects concrete as a material which has been at the vanguard of modern building construction. In Nigeria, 60% of the components of cement are imported by most cement factories. The cost of materials accounts for about 40% of production costs while energy costs account for 30-40% of the total production costs. Coupled with transportation costs which inflate the unit price of cement bags in direct proportion to the distance; these costs have made the deployment of cement based construction for affordable mass housing rather difficult.

In response to the problems posed by modern construction methods, research in raw earth construction has gone a long way in showing the versatility, functionality and cost effectiveness of earth as a construction material. Development programmes geared towards the harnessing and development of this technology for architectural application in the past have provided an avenue for:

1. Expression of cultural identity in traditional building techniques
2. Initiating development plans which are not capital intensive but labour intensive. Such cost effective schemes would help developing nations with effective debt management.
3. Technology transfer and inter boundary diplomacy between developing nation states and advanced countries which have pioneered the adoption of raw earth architecture.
4. Maintenance of the ecological balance while cutting down on the unemployment figures of developing nations.

Modern cities and settlements executed in splendid styles and versatile forms by the CRATerre group in affiliation with the Grenoble Architecture School in France show just how raw earth can be applied to exquisite modern taste. City blocks and housing schemes in Mali, Morocco and Saudi Arabia, executed with raw earth, show how relevant it is to developing states and how well it fares in competition with other construction methods.

Raw earth structures have been existing in practically every state of the country for several centuries. The obvious reason for this is the basic nature of the material, its ready availability and easy manipulation and durability even well and above that of stone or timber structures. The flexibility of the material is well exhibited in the variety of expressions of earth forms across the cultural, religious and climatic regions or terrains of Nigeria. The northern regions have the tradition of using conical sun dried earth bricks (tubali) for their residential houses and monumental structures like mosques and palaces, characterized by domed roofs. The central and south – eastern parts of the country are known for clustered huts made of puddled earth laid in wet courses. Colonnades are common to support overhanging thatch roofs which protect the earth walls. South - western Nigeria is known for houses and palaces built around spacious courtyards with earth walls and thick columns linked by strong beams. Down south, raw earth is padded unto linear wood structural frames to form composite walls which could easily be load bearing.

The different zones exhibit a uniqueness in the application of the material, based on their varying climatic and cultural characteristics. Up north, the walls are left exposed and are even decorated with motifs which remain for several years. This also makes it possible to experiment with different molded forms for the walls which are the most prominent building elements unlike down south (with higher annual rainfall) where the overhanging protective roofs dominate. Walls in South eastern Nigeria are sometimes decorated with incisions or with indigo coloured pigments (Uli) while buildings in south – western Nigeria could have their earthen columns sculpted into caryatids or other interesting forms.

True ‘return to earth’ will require a study of the traditional building systems in earth technology that evolved over time, to gather basic evidence of their successes and failures which can then guide the material’s usage in a modern context.

This need to research our traditional building forms must have informed the creation of the Museum of Traditional Nigerian Architecture (MOTNA) in Jos. Set within the sprawling 80 acre boundary of the Jos Museum, MOTNA is a live project that replicates at full scale, the major types of traditional built forms (all in raw earth) from across the different regions of the country. Of the 48 models intended, over one third have been completed, including models of well known structures like the ancient Kano city walls, Zaria Friday Mosque, Pategi Compound, Mbari Shrine, Rukuba Compound, Benin Palace, amongst others. This rich store of cultural and technological information has turned the Jos Museum into a choice tourist destination. MOTNA commands attention for its daring scale as an open air museum, a classification it shares with very few others in Africa. It is instructive to note that Jos Museum is of major relevance to the revival of earth construction in Nigeria, not just because it houses MOTNA, but also because Jos Museum in the past has been host to technical workshops on earth construction methods that exposed museum staff and interested professionals in the building construction industry to modern possibilities in raw earth construction.

A visit to the Lagos station of the National Museum, where the bamboo huts that once characterized the craft village area are being replaced with raw earth structures; would show how some of those possibilities are being explored today. According to Messrs Folaranmni Adebayo and Festus Owojaiye, technical officers of the museum attached to the project, the new buildings are being erected with solid compressed earth blocks of 4 inches by 12 inches which are made with a molding machine and technical knowledge brought in from Jos. The compressed blocks are made from cement stabilized earth: 19cm³ of cement to 4 wheel barrows of laterite (red) sand. The resultant blocks are rock solid after curing for 7 – 10 days and can then be laid in courses like regular sand-crete blocks or burnt bricks. Sourcing the laterite sand of the correct consistency could be a challenge in Lagos where sandy and loamy soils are prevalent. For the current project which complements the popular Museum Kitchen that has continued to stand tall with its earthen walls through generations of use; laterite soil had to be source form the Mowe – Ibafo area, right outside Lagos at the cost of N8,500 per tipper as against N1,500 which would have been obtainable up north where the soil type is more prevalent. Though this makes it difficult in Lagos to benefit from the cost savings that should have been the norm when building with earth, it is not the case in other parts of the country (or other parts of Lagos for that matter) where red earth is readily available in abundance.

Another perceived deterrent to the widespread adoption of raw earth building construction in rainforest regions like Lagos is the fear that earth walls would fail under the constant influence of driving rain and floods. However, that fear is unfounded when earth buildings are conceived with the right design considerations for the regions where they are to be erected. With a good hat (effective roofing system) and a good pair of shoes (a secure / raised foundation) raw earth walls would hold their own against all odds in regions with high annual rainfall. Many buildings have been standing for over a hundred years in those regions to lend credence to the fact.

Through the current project, the Lagos Museum hopes to increase awareness for earth construction and to provide technical consultancy for individuals and organizations that show interest in adopting the building material and techniques.

So, mud house….anybody?

-Ayodele Arigbabu.
arigbs@gmail.com

published in The Guardian Life Dec 04-10, '05