Modular Thatch Roof in Kutch, Gujarat (adapted from Bali, Indonesia) — Artisans in Architecture

Modular Thatch Roof in Kutch, Gujarat (adapted from Bali, Indonesia) - Artisans in Architecture

Title

Modular Thatch Roofs in Kutch (adapted from Bali, Indonesia)

Summary

Modular thatch roofing covers the roof surface with units (similar to tiles) made out of locally available thatch. Instead of the entire process being done on the roof, this type of roofing is constructed on the ground, separately from the under structure of the roof and later it is tied to the roof structure. Separating these two processes of construction — roof understructure and roofing results in saving time and reducing the efforts of working on the roof. It is also convenient to do quality check and consistency maintenance on ground along with improving the efficiency.

In this type of roofing, the thatch is not fully exposed to the weather. Since the modules made out of thatch are overlaid on each other such that only 1.5 to 2 inches of thatch towards the end is exposed to the weather. Hence the life of the thatch roof is much longer than traditional roof construction with thatch. In general, the roof with modular thatch roofing lasts between 12 to 15 years before thatch needs to be replaced.

Modular thatch roofing system has been in practice successfully in Bali (Indonesia) even today. The other important factor for its wide application is easy availability of materials and skills to construct it. Having a tropical climate (in Indonesia), it very easy to get the Paddy leaves and Bamboo as the basic roofing materials. Also, there is a large number of skilled artisans still available to construct this type of roof system.

This system of thatch based roofing construction can be useful in India too, where thatch is amply available and very much affordable material. Being porous material, it helps in temperature control. Also, due to its light weight it does not require heavy supporting structure. This not only helps controling the cost but also is safer in case of structural failure or failures due to disasters. Yet, there are reservations against it due to its labour intensive construction methods. Slowly, the thatch is being eliminated from vernacular construction.

This documentation focuses on the technical aspect of modular thatch roofing system and try to adapt it to Indian context and climatic conditions.

Location

Roof using the modular thatch roofing system are widely used in Indonesia and specially in the Bali region. It is found on the roofs of traditional houses, temple complexes and in modern context, also on luxury resorts etc.

Context

Indonesia:

Indonesia has tropical, hot and humid climate, while Indonesian highlands observe more moderate climate. Throughout the year, there is not much variation in temperature because of almost uniformly warm waters that are part of the archipelago. In much of western Indonesia dry season lasts between June to September, rainy season prevails between December to March. In such climate, grass and bamboo grow amply. The humidity level is generally high and protection from the rains is very much required. The climate also requires that the rooms are protected from heat. Grass and bamboo both are amply available in tropical climate of Indonesia. Due to the materials used for this roofing, it responds well to the climatic conditions as this roof is porous and hence comfortable in the heat. In such context, thatch as roofing material is very natural to have been used.

Kutch is very different in terms of climate and geography. Opposed to hot and humid tropical climate of Indonesia, Kutch has hot and dry climate. Though both the places have ample amount of grass available that can be used for thatch roofing and also good traditional know how of working with materials. Furthermore, the scarcity of resources and good adaptation skills means that modular thatch roofing can be a good example for transformation for Kutch.

Geography: Kutch, the second largest district in India (reference required) is surrounded by the Gulf of Kutch and the Arabian Sea in south and west, while northern and eastern parts are surrounded by the Great and Small Rann (seasonal wetlands) of Kutch. Kutch or Kachchh, as it is in Gujarati, literally means something which intermittently becomes wet and dry. The same word is also used in the languages of Sanskrit origin for a tortoise and garments to be worn while having a bath. Large part of this district known as Rann of Kutch is shallow wet-land which submerges in water during the monsoon and becomes dry during other seasons.

Climate: Kutch has hot and dry climate with very little rains.

Summers- the cool wind in the evenings/night needs to be brought into the house from the south west; however the day sun/heat needs to be avoided from the south.

Winter- the sleeping room needs to be closed from the night cold of desert, but the day sun is welcome, though during most times it can be quite harsh.

Monsoon- rain is less but can come down in torrents and generally comes from the S-W direction.

Though the monsoon is very short, there are heavy showers of rains during the monsoon. Thus, for a short period of time, protection from rain is necessary. During the hot and dry summers, protection from heat is very essential as the temperature rises upto 45 degrees or more.

Natural Disasters: Most of the area of Kutch is highly vulnerable to many natural disasters. Below mentioned are some of the natural calamities that were registered in Kutch in past:

Earthquakes- Whole of Kutch falls under Zone V of earthquake vulnerability. Observations suggest that it has a 50 year cycle with earthquakes ranging between 7 to 9 intensity on Richter scale. Last significant earthquake was observed on 26th January, 2001. after that also many minor earthquakes are observed in the region.

Cyclones- with 220km of coastline cyclonic winds are very common here. Winds upto 180-200 kmph are commonly observed. Last cyclone in July,1999 hit Abdasa in Kutch which recorded speed of 180kmph.

Floods- Banni region of Kutch has area of 4500 sqkm which has clayey soil. This flat region with elevations ranging from 7-14m above sea level observes periodic floods. Though monsoon is short and rain scarce, the wetlands are flooded regularly while the other part of the region faces frequent draughts and Kutch is famous for its scarsity of water.

materials: Variety of grasses are available in the grazing lands of Kutch. Traditionally, thatch is widely used as roofing material combined with wooden understructure. Though, the traditional technique of using thatch in Kutch is very different from that used in Indonesian roofing, there are many skilled artisans who use thatch roof construction.

Housing/ Settlement Typology

As discussed in the summary, this type of roof is used to cover various spaces. The modular thatch roofing can be used in different combinations of walls and roof structures. The walls can be made of earthen block masonry, rammed earth, brick masonry, stone masonry, adobe construction or wattle and daub construction, while the roof understructure can be made out of wood, bamboo or steel in form of truss or space-frame. Even other variations using frame structure instead of load bearing walls are also easily possible.

The buildings using this roof may have variety of spans from 10 to 12 feet (for house) upto 30 feet or more depending on the space and functional requirements. In a training centre at Kukma village near Bhuj a roof is constructed with wooden understructure and modular thatch roofing that spans 30 feet X 30 feet 1 .

Knowledge System/ Innovation

Disaster Resistance/ Structural System

In the unit based roof construction with thatch, the thatch is tied properly to the wooden members to make the thatch modules. These modules are further anchored to the roof structure. Thus, the thatch is properly tied to the structure of the roof and hence the damage due to heavy wind or in cyclone is reduced.

Also, thatch being light weight the roof does not require heavy structure for support. It also helps reducing the damage to life and assets in case of failure of roof structure due to earthquake or cyclone.

Climate response

In extreme hot climate of the region, thatch roof reduces the temperature of interior rooms due to its thickness and porosity. The temperature reduction recorded at under such thatch roof in peak summer in Kutch was 9 to 10 degrees. (further details of the measurements and conditions/dates etc.).

A well constructed thatch roof can provide sufficient protection during the monsoon rain due to overlapping of the thatch.

Title

Modular Thatch Roofs in Kutch (adapted from Bali, Indonesia)

Summary

Modular thatch roofing covers the roof surface with units (similar to tiles) made out of locally available thatch. Instead of the entire process being done on the roof, this type of roofing is constructed on the ground, separately from the under structure of the roof and later it is tied to the roof structure. Separating these two processes of construction — roof understructure and roofing results in saving time and reducing the efforts of working on the roof. It is also convenient to do quality check and consistency maintenance on ground along with improving the efficiency.

In this type of roofing, the thatch is not fully exposed to the weather. Since the modules made out of thatch are overlaid on each other such that only 1.5 to 2 inches of thatch towards the end is exposed to the weather. Hence the life of the thatch roof is much longer than traditional roof construction with thatch. In general, the roof with modular thatch roofing lasts between 12 to 15 years before thatch needs to be replaced.

Modular thatch roofing system has been in practice successfully in Bali (Indonesia) even today. The other important factor for its wide application is easy availability of materials and skills to construct it. Having a tropical climate (in Indonesia), it very easy to get the Paddy leaves and Bamboo as the basic roofing materials. Also, there is a large number of skilled artisans still available to construct this type of roof system.

This system of thatch based roofing construction can be useful in India too, where thatch is amply available and very much affordable material. Being porous material, it helps in temperature control. Also, due to its light weight it does not require heavy supporting structure. This not only helps controling the cost but also is safer in case of structural failure or failures due to disasters. Yet, there are reservations against it due to its labour intensive construction methods. Slowly, the thatch is being eliminated from vernacular construction.

This documentation focuses on the technical aspect of modular thatch roofing system and try to adapt it to Indian context and climatic conditions.

Location

Roof using the modular thatch roofing system are widely used in Indonesia and specially in the Bali region. It is found on the roofs of traditional houses, temple complexes and in modern context, also on luxury resorts etc.

Context

Indonesia:

Modular Thatch Roof in Kutch, Gujarat (adapted from Bali, Indonesia) - Artisans in Architecture

Indonesia has tropical, hot and humid climate, while Indonesian highlands observe more moderate climate. Throughout the year, there is not much variation in temperature because of almost uniformly warm waters that are part of the archipelago. In much of western Indonesia dry season lasts between June to September, rainy season prevails between December to March. In such climate, grass and bamboo grow amply. The humidity level is generally high and protection from the rains is very much required. The climate also requires that the rooms are protected from heat. Grass and bamboo both are amply available in tropical climate of Indonesia. Due to the materials used for this roofing, it responds well to the climatic conditions as this roof is porous and hence comfortable in the heat. In such context, thatch as roofing material is very natural to have been used.

Kutch is very different in terms of climate and geography. Opposed to hot and humid tropical climate of Indonesia, Kutch has hot and dry climate. Though both the places have ample amount of grass available that can be used for thatch roofing and also good traditional know how of working with materials. Furthermore, the scarcity of resources and good adaptation skills means that modular thatch roofing can be a good example for transformation for Kutch.

Geography: Kutch, the second largest district in India (reference required) is surrounded by the Gulf of Kutch and the Arabian Sea in south and west, while northern and eastern parts are surrounded by the Great and Small Rann (seasonal wetlands) of Kutch. Kutch or Kachchh, as it is in Gujarati, literally means something which intermittently becomes wet and dry. The same word is also used in the languages of Sanskrit origin for a tortoise and garments to be worn while having a bath. Large part of this district known as Rann of Kutch is shallow wet-land which submerges in water during the monsoon and becomes dry during other seasons.

Climate: Kutch has hot and dry climate with very little rains.

Summers- the cool wind in the evenings/night needs to be brought into the house from the south west; however the day sun/heat needs to be avoided from the south.

Winter- the sleeping room needs to be closed from the night cold of desert, but the day sun is welcome, though during most times it can be quite harsh.

Monsoon- rain is less but can come down in torrents and generally comes from the S-W direction.

Though the monsoon is very short, there are heavy showers of rains during the monsoon. Thus, for a short period of time, protection from rain is necessary. During the hot and dry summers, protection from heat is very essential as the temperature rises upto 45 degrees or more.

Natural Disasters: Most of the area of Kutch is highly vulnerable to many natural disasters. Below mentioned are some of the natural calamities that were registered in Kutch in past:

Earthquakes- Whole of Kutch falls under Zone V of earthquake vulnerability. Observations suggest that it has a 50 year cycle with earthquakes ranging between 7 to 9 intensity on Richter scale. Last significant earthquake was observed on 26th January, 2001. after that also many minor earthquakes are observed in the region.

Cyclones- with 220km of coastline cyclonic winds are very common here. Winds upto 180-200 kmph are commonly observed. Last cyclone in July,1999 hit Abdasa in Kutch which recorded speed of 180kmph.

Floods- Banni region of Kutch has area of 4500 sqkm which has clayey soil. This flat region with elevations ranging from 7-14m above sea level observes periodic floods. Though monsoon is short and rain scarce, the wetlands are flooded regularly while the other part of the region faces frequent draughts and Kutch is famous for its scarsity of water.

materials: Variety of grasses are available in the grazing lands of Kutch. Traditionally, thatch is widely used as roofing material combined with wooden understructure. Though, the traditional technique of using thatch in Kutch is very different from that used in Indonesian roofing, there are many skilled artisans who use thatch roof construction.

Housing/ Settlement Typology

As discussed in the summary, this type of roof is used to cover various spaces. The modular thatch roofing can be used in different combinations of walls and roof structures. The walls can be made of earthen block masonry, rammed earth, brick masonry, stone masonry, adobe construction or wattle and daub construction, while the roof understructure can be made out of wood, bamboo or steel in form of truss or space-frame. Even other variations using frame structure instead of load bearing walls are also easily possible.

The buildings using this roof may have variety of spans from 10 to 12 feet (for house) upto 30 feet or more depending on the space and functional requirements. In a training centre at Kukma village near Bhuj a roof is constructed with wooden understructure and modular thatch roofing that spans 30 feet X 30 feet 1 .

Knowledge System/ Innovation

Disaster Resistance/ Structural System

In the unit based roof construction with thatch, the thatch is tied properly to the wooden members to make the thatch modules. These modules are further anchored to the roof structure. Thus, the thatch is properly tied to the structure of the roof and hence the damage due to heavy wind or in cyclone is reduced.

Also, thatch being light weight the roof does not require heavy structure for support. It also helps reducing the damage to life and assets in case of failure of roof structure due to earthquake or cyclone.

Climate response

In extreme hot climate of the region, thatch roof reduces the temperature of interior rooms due to its thickness and porosity. The temperature reduction recorded at under such thatch roof in peak summer in Kutch was 9 to 10 degrees. (further details of the measurements and conditions/dates etc.).

A well constructed thatch roof can provide sufficient protection during the monsoon rain due to overlapping of the thatch.

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