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Alang Alang Thatched Roofing

Alang alang thatching has been used in Indonesia for hundreds of years on the islands of Bali, Lombok, Sumbawa, Timor and Sumba as a traditional system of roofing. There are slight variations in the application of the material throughout these different places but by far the neatest and strongest form is found in Bali .

The blades of alang alang thatching are constructed from the grass Imperata Cylindrica which is called locally ambongan. It is also called alang in Indonesian and Malay. It is known in Australia as bladey grass because of its tendency to cut skin. It is a tough and resilient grass and grows best in harsh conditions and poor ground. Some of the strongest examples are found on sandy margins at the edge of beaches and on cliff tops. Because of the demand for alang alang for tourism projects in Bali and the loss of the beachfront margin to hotels, there has been a lot of grass production in fertile soils that were normally used for other farming, also using fertilizer to allow faster harvesting. The alang alang made from this raw material is inferior which shortens the lifespan of the roof material.

The alang alang roof is good insulation against heat and is very attractive to look at, both inside and out. It is durable, with reports of it lasting to twenty years, although by this time it would be very thin and unattractive. More commonly it has a life span of seven or eight years.

The actual life span depends on many factors. An alang alang roof, as it is made from organic materials, is constantly under a process of decomposition. Modern Balinese roofs that we have documented have lasted from between seven and fifteen years. The factors that have affected these periods of time are the quality and quantity of material used to fabricate the original elements, the pitch of the roof, wind damage, whether there is water from an upper roof falling on it and whether there is overhanging trees that both drop leaves and prevent the outer surface from drying during sustained periods of rain.

The only negative comment made about alang roofs in Bali is the amount of dust from the small insects that have their life cycle in the bamboo rafters and the battens that form the spines of each individual piece of alang alang.. There is very little dust, however, from the inner surface of the alang alang as it is not attacked by insects and is hardly decomposing.

Alang alang roofs require no finishing or maintenance but a spraying with a varnish of the inside can enhance their appearance.