Vernacular heritage in Bhutan at risk: a manual for conservation and maintenance of rammed-earth buildings

Bhutan is a small country located on the slopes of the Himalayas, which is an area characterized by frequent earthquakes due to the collision of the Indian and Eurasian plates; despite there’s no record of earthquakes greater than 7 magnitudes in the twentieth century, the country appears to be in an area at risk and with a high probability of having other earthquakes of greater intensity in the future. Furthermore, the climatic conditions, the difficult environment and the predisposition to natural disasters put the population and its housing to frequent tests. Nowadays, it is not very hard to find buildings constructed of reinforced concrete in the urban areas of the country; on the contrary, in the rural ones, where the majority of the population reside, the buildings are constructed of raw earth or stone. These traditional constructions are particularly vulnerable to earthquakes due to the lack of seismic resistant technologies, as happened in 2009 in the east of Bhutan and in 2011 with the earthquake on the Indo-Nepalese border. At present there are no guidelines or policies for the conservation and structural reinforcement of traditional earthen buildings, although the government has focused in particular on the preservation of Bhutanese vernacular buildings, especially with the publication of the last “Five Years Plan”. The Kingdom of Bhutan due to rapid urbanization and modernization of construction technologies is placing more attention and efforts to promote and preserve the cultural heritage that comes from vernacular architecture, represented by temples “Lhakhang”, fortress “Dzong” and traditional dwellings “Yue Chim”; thanks to this conscious vision of the uniqueness and richness of the heritage that there is the possibility of developing a search for conservative technologies for buildings built of rammed-earth. This thesis work therefore arises with the aim of proposing a manual of intervention for vernacular buildings in rammed earth damaged by the earthquake. In the light of the damages assessments, it has been done an analysis of the causes that may have contributed in the case of damage or collapse of a building, which is not always related only to the earthquake tremors. The research therefore, continued with the identification of appropriate techniques and materials to repair the effects of the damages, always in consideration with the socio-economic possibilities and local resources of the population in respect of the traditional architecture style. The concepts introduced, focus onto the development of a seismic culture by the local population for the vernacular buildings in which they reside, in order to mitigate and prevent structural damage in future earthquakes. Although the manual itself will not be distributed directly to the population, if not with accurate experimentation by researchers of the Satreps program and workshops to craftsmen, this arises with a language as simple as possible and with the use of graphic drawings to explain step by step the repair actions that have to be undertaken, as the final goal is the proposal of interventions easy to understand and repeat by the local population.