Rammed earth

What it is

In rammed earth construction, unfired earth is filled and compacted block by block between two shuttering boards; in French these boards are called banches.¹ Ramming shrinks the earth to about half its volume, and once dry it becomes almost as hard as stone.² In southern Morocco, rammed earth is the main technique for load-bearing walls; mud bricks (adobe) serve for the upper storeys of the towers, for parapets, decorative features, partition walls, stairs and columns.³

A ksar (plural ksour) is a communal settlement behind walls with corner towers, in which houses, stables, granaries, market square, assembly room, mosque and madrasa stand together.⁴ The kasbah, by contrast, in Tamazight tighremt, is the large house of one family around a rectangular courtyard with four fortified wings; it can be a farmhouse, as in the Skoura oasis, or a palace the size of a small village, as in Taourirt or Telouet.⁵ Southern Morocco has around 300 kasbahs and 4,000 ksour, spread over the valleys of the Draa, Dadès, Ounila and Ziz on the edge of the Sahara.⁶

Where it comes from

According to ICOMOS, the earthen buildings of the south belong to a building tradition of the areas on the edge of the Sahara that is found throughout the Maghreb from Mauritania to Libya; the building form and technique were probably brought into the mountains and valleys of the south very early on by masons of Saharan origin.⁷ The best-known ksar of the Ounila valley is Aït-Ben-Haddou in the province of Ouarzazate, 31 kilometres from the town, on the southern slopes of the High Atlas; it was one of the trading posts on the route from the old Sudan through the Draa valley and over the Tizi n'Telouet pass to Marrakesh.⁸

History

Whether this way of building arose with Islamisation and the founding of Sijilmassa in 757 is uncertain; the oldest surviving buildings do not seem to go back before the 17th century, even though the form and technique are much older.⁹ Like the oasis valleys, the Ounila valley has been protected since 1953¹⁰, and Aït-Ben-Haddou has been a UNESCO World Heritage Site since 1987, with a core zone of 3.03 hectares and a buffer zone of 16.32 hectares.¹¹ The ksar of Taourirt, today in the middle of the town of Ouarzazate, also dates from the 17th century; its kasbah, national heritage since 1954, was a residence of the Glaoui and was extended at the end of the 19th century by Si Hammadi el Glaoui into a walled complex with stables, workshops, market, wells and hammams.¹² In 1972 the heirs sold the kasbah to the municipality of Ouarzazate; from 2011 the Getty Conservation Institute and the state centre CERKAS drew up a conservation plan intended to preserve the traditional earthen building techniques.¹³

What it is made of

According to ICOMOS, Aït-Ben-Haddou shows the whole range of building techniques on the edge of the Sahara: rammed earth laid in stretchers and headers, ordinary rammed earth and mud bricks.¹⁴ The building materials are still earth and timber; attempts to introduce cement have so far been warded off by the supervisory bodies.¹⁵ In general, local earth with little clay and no fibres, taken from below the humus layer, is suitable.¹⁶ For the restoration of the Kasbah of Taourirt, earth from 15 kilometres away was used, 67 per cent sand and 33 per cent clay, a ratio regarded as suitable for rammed earth and matching the original earth of the site.¹⁷

How it is made

The shuttering boards are about two to three metres long and around 60 centimetres high, and the walls are 50 to 60 centimetres thick; compaction is done with a hand rammer.¹⁸ After each section the formwork is moved, so that the wall grows layer by layer; doors and windows are left open as it goes up.¹⁹ In Taourirt the rammed-earth walls are 60 to 80 centimetres thick, the foundations consist of large stones, and short timbers reinforce the corners; the decorative features in mud brick are coated with earthen plaster.²⁰

In the restoration at Taourirt, the slightly moistened earth is filled into metal formwork and compacted with a pneumatic rammer, which in southern Morocco has largely replaced the more laborious wooden rammer; the blocks measure about 85 by 250 by 60 centimetres and are joined with wooden wedges.²¹ The earthen buildings are very vulnerable when care and regular repair are lacking.²² In 1986 ICOMOS recommended making Aït-Ben-Haddou a test case for conservation drawing on the traditional techniques of earth and timber work²³; today CERKAS, the Centre for the Conservation of the Built Heritage of the Atlas and Sub-Atlas Areas, monitors the ksar and implements its management plan.²⁴

How to recognise it

Hallmarks of the ksour are the corner towers, whose upper parts are decorated with patterns of mud brick.²⁵ Often there is also a fortified granary on a hill, called agadir or ighram, as above Aït-Ben-Haddou.²⁶