Typhoon Resistant Building in Vietnam : a programme for reaching people.

John Norton, Development Workshop
Guillaume Chantry, GRET
Nguyen Si Vien, IBD Hué

Each year typhoons sweep across the central and northern coastal plains of Vietnam, leaving a trail of death, destruction to property and infrastructure, and loss of crops. In the aftermath the population mobilises to rehabilitate their region. Scarce resources of materials and money are consumed in the effort: those same resources that should be far better used for the development of the region.

Much damage could be reduced, and far less effort and money consumed, if preventive steps were taken to make buildings stronger against typhoons. This article describes a programme started in January 1989 in the provinces of Quang Binh, Quang Tri and Thua Thien (BTT zone)(1) , aimed at reducing typhoon damage by raising awareness about the need to protect buildings and about the techniques that can be used to achieve this. The BTT programme was initiated on request from the Vietnam government by UNCHS Habitat, and designed and implemented by Development Workshop (DW), GRET, the Institute of Building Design (IBD) in Hué, and the Institute of Housing and Public Building Design (IHPBD) in Hanoi.

In 1999, Development Workshop has renewed activities in Central Vietnam on the same theme, with support from Alternative Action, Canada and CIDA Humanitarian Aid.

Building in BTT and resistance to typhoons
Most buildings in BTT zone are small dwellings with adjoining structures for kitchens, selling, workshops and animal sheds. Apart from a few major public buildings, the public buildings use forms and methods similar to those used in the smaller domestic building, and, for storm resistance, present similar strengths and weaknesses. Most buildings can be considered primarily in terms of a supporting framework holding up the roof. The walls are usually lightweight, often contributing little to the structure. One can identify three main families of construction: the traditional buildings; buildings with a mixture of materials and techniques - the "transition" house evolving towards the "modern" dwelling; and the local public buildings in the districts of each province. The latter two are jointly characterised by poor detailing and frequent poor quality; since they increasingly represent the building stock of the area, they are the major preoccupation for typhoon resistant construction.

Traditional buildings, whether on the scale of the region's palaces, tombs and temples, or that of the house, exhibit quite consistent characteristics: a framed structure with many substantial heavy wooden posts and short span beams, held together by finely executed mortise and tenon joints. The roof, often with hipped ends, is an integral part of this framing. Between the structural elements the infill walls use various materials, from wattle and daub through to fired brick or timber shutters. On tiled roofs it is common to see exposed masonry ribs which help hold down the covering.

The combination of good jointing, small structural units and large timbers give the traditional building structural integrity and stiffness: these make traditional buildings very able to resist typhoons. Increasing scarcity of timber has pushed costs up, making the construction of a traditional house very expensive: nevertheless, one still finds the traditional beautifully executed timber frame used in new houses, and regarded as a status symbol. Sadly, the quality of walls and roof covering are not always of similar standard, and this is but one example of the second category of houses and public building in the area: the transition building.

Contemporary habitat: the "transition" building.
Today, a wider variety of materials and techniques are employed than in the past, some use the hybrid forms of traditional building, others attempts to apply new techniques and new materials such as reinforced concrete, often without the necessary skill or the money to get it right. The poor depend on using straw, leaves, branches and bamboo. Construction of most houses is an ongoing process: with the difficulties of acquiring materials, various elements that make up the building are often linked together in a haphazard manner, more influenced by what is available at the time than by what might best protect and secure the investment that is being made. These buildings are characterised by the weakness of the joints between elements, which thus easily fail; and by the increasing lightness and lack of rigidity in the structure, offering less resistance to high wind pressures. Everyone would like a version of the "modern house", which once complete offers quite good typhoon resistance: but in the meantime the step by step investment made in materials such as tiles, bricks and cement is at high risk from frequent typhoons. This is exacerbated by poor workmanship.

Public buildings
Public buildings, although designed by technicians, are similarly at risk to storms. The same weaknesses in detailing and execution are compounded by the design of the buildings: a trend towards high un-triangulated structures, the use of gable end walls with little rigidity, large verandas where the roof is greatly exposed to uplift. Typhoon Irving in 1989 highlighted this problem, with the collapse of hospitals and schools in the Thanh Hoa province(2) .

Costs
Construction is not cheap. At 1989 prices(3) , a thatch and bamboo frame structure cost 50,000 Dong/m2; a bricks and tile roof structure 200,000 Dong/m2, and a reinforced concrete structure with concrete roof some 300,000 Dong/m2. Compared to the monthly wage of local engineers, in the order of 45,000 Dong/month, one has an idea of the magnitude of the investment. The affordability of housing is worse for farmers and fishermen, with an average family revenue of 40,000 Dong and often less.

Typhoon damage and cost: prevention or recovery?
Typhoons of varying intensity hit the Vietnam coast: those with small intensity which come every year, where damage should be limited; medium, so-called "10 year" typhoons causing far more major damage; and massive "100 year" typhoons which cause major devastation. The effect of typhoon winds for all but the frailest structures is progressive: in a medium typhoon bamboo and thatch shelters collapse rapidly under the initial buffeting of the wind. Damage to more substantial buildings comes in a sequences of events, where elements are weakened or loosened by pressure and suction: the tiles lift on the eaves and ridges, the complete roof blows away, followed by roof frame collapse. Walls are either flattened or carried off, depending on the structure. Rapidly, 70 or 80% of the building can be razed to the ground; 40 to 50% of the materials lost beyond recovery. Against this cost and loss, comprehensive surveys carried out by BTT programme participants during `89 and '90 showed that an extra construction investment of 10% (on more solid buildings) to 30% (on thatch and bamboo shelters) would make most buildings able to resist small and medium scale typhoons, the latter seeming to occur more frequently than every ten years. It was thus a major task of the BTT programme to persuade people to spend time and money on preventive action in order to secure their investment in the "transition" building.

Who builds and how?
Houses in the BTT zone are usually built by local builders, employed somehow even in the simplest construction. The family helps with the work. Local materials are used for the most part. Usually little or no attention is paid to typhoon resistant construction details and there are no regulations. When a typhoon arrives, last minute measures are taken to stop the tiles blowing off, or the walls collapsing: by this time it is often too late. Public buildings, designed by provincial and district technicians who carefully follow rules for reinforced concrete design, have had habitually little attention paid to typhoon resistant detailing and form. The local building brigades and contractors who do the construction have little contact with the designer, and pay even less attention to quality control: this sad state of affairs has become too often the accepted norm. After a typhoon, the population and the province mobilises in a major effort to reconstruct, but the quality of work that contributed to the collapse of the building beforehand is now repeated: at the next typhoon the building will be just as much at risk. Thus the cost of recovery is compounded by its repetitive nature.

A programme to create a local capacity
In1989 the UN funded a programme followed the massive 1985 typhoons which devastated the Binh Tri Thien zone, leaving 875 persons dead, 49,000 houses destroyed and 230,000 damaged, 2,600 classrooms destroyed, and 6 hospitals and 250 health centres damaged.
Implemented by DW/GRET, the programme's objectives were clear from the outset:

In implementing these objectives, one of DW/GRET's local partners, the IBD Hue, has progressively taken a leading role in maintaining the programme.

How to achieve a local capacity
The programme focussed on three levels of activity:

Developing the organisational as well as the technical skills of the technicians and builders in each province has formed the backbone of the programme. Each provincial seminar has involved the participants in theoretical and practical work: conducting village level surveys to find out the weak points of local construction, how local buildings can be made to resist typhoons, and with what locally available resources; exploring ways in which this information can be transferred to the population: and detailing the extra costs involved. The participants produced technical dossiers for each aspect, and produced the media they felt best suited to inform the public: posters, poetry, radio and video materials including a short film(4).
Central to the programme has been the of "ten key principles of typhoon resistant construction": principles which can be adapted to suit local realities rather than norms which cannot be applied by the population: Use topography to shelter your building; keep the building form simple with minimum obstruction to the wind; pitch the roof between 30° and 45° to lower wind suction; avoid large overhangs, and separate the veranda from the house; tie the whole structure firmly together; use diagonal bracing; fix down the roof covering; balance the size of openings; if you can, make sure that all openings can be closed; and plant wind breaks.
During each seminar, the participants also designed, and subsequently constructed of a public building. These buildings - a primary school, a health centre, and a library - have provided the opportunity to demonstrate the application of the "ten key principles". They have given first hand experience to local builders and technicians, particularly with respect for quality control on the building site

How to get the message to the public?
The most fundamental action in the programme has been to inform the population about the need to protect their buildings, about the ways that this can be done, and who can help them - the builders and technicians trained in the programme. Following an encouraging trial campaign in January 1990. a major campaign was launched in Thua Thien Province in April 1990, reaching some 500,000 people in communes affected by typhoons. The campaign activities have been multiple and rich. In Hué, newspapers ran full-page articles prepared by the IBID Core team. The team toured the province to lecture, and appeared on local TV with provincial leaders to carry the message further. Local radio announced the programme and the time of showings for the video, watched each time by several hundreds of people prior to main feature films, already a regular event. Locally photo and drawing exhibitions showing action against natural calamities were organised, and in the schools competitions were held for poetry and drawing about the `Campaign for Typhoon Resistance Building'. Throughout the province the Women's Union, The Youth Union and the Farmer's Union organised public gatherings on the same theme. All over the province over 2,500 large posters were shown in gathering places, the markets, bus stations and cafés. On the Provincial Day of Disaster Preparedness, the 26th April, youth brigades paraded the streets of each District with specially prepared banners, and the Radio and TV ran special programmes. This campaign met with great enthusiasm and several Districts prolonged activities into a second month.

A plan of action in place
Developing out of the work of the seminars, and embodied in the first public information campaigns, has been a plan for assuring the spread and application of typhoon resistant building techniques, first in the provinces of the programme, and gradually into other provinces, to become a national programme. Its execution brings together three levels of action. At Province level, the Building Institutes constitutes the Typhoon Resistant Construction Unit. The Unit organises the programme, prepares training and information materials, trains district technicians, and constantly evaluates and improves the programme. At District level, existing local technicians, now trained in Typhoon Resistant Construction Techniques, become the local public advisers, helping families and training local builders. They advise too how the Core teams should improve the programme. And at the Commune level, the local mason and carpenter, once trained, through involvement in domestic building activities provide practical advice in house design and materials choice.
In the plan's application, the experience of 1990 showed the important role that local institutions for information dissemination, for education, and for political decision have to play: mobilising resources - of people and money -, and in complementing the skills of the Core Teams.
The impact of the BTT programme was positive even though time was too short: the constitution of specially trained teams, a process of training technicians and builders which has been tried and tested, and the development of an excellent local knowledge of `what is possible'. Linked to the experience of the public information campaigns, this represents a real capacity to identify applicable techniques, evaluate them, and assure their diffusion. Nevertheless, after two years of action, the programme must still confront some major issues. It is clear that for many families who live in the frail thatch, branch and bamboo structures, there is still almost no chance that their homes will resist a typhoon: the extra cost is prohibitive. It is realistic to envisage the improvement of "transition" buildings, to resist at least a medium "10 year" typhoon; but still there is insufficient protection against the massive "100" year typhoons, frequent in recent years, which destroy essential public infrastructure as much as private homes. The economic situation of the country and the people imposes severe limitations on what can in reality be achieved.

For the individual family, the notion of spending extra scarce resources on protection against a typhoon that may not hit your home remains hard to accept: child vaccination against disease is becoming accepted; "vaccinating" your home against typhoon damage still needs much promotion and active demonstration of the benefits it brings. These remain the tasks for the years ahead.

(1) Until Jully 1989, these three provinces were known as Binh Tri Thien province. Quang Binh has a population of 646,000; Quang Tri 458,000; and Thua Thien 891,000 (1989 figures).

(2) Thanh Hoa province, just to the north of the BTT provinces was hit by a major typhoon in October 1989 which caused extensive damage: DW & GRET were called in to provide rehabilitation assistance, and at their instigation involved the Vietnamese institutes of IBD Hué and IHPBD Hanoi.

(3) 1US$ = 4500 Dong in 1989.

(4) We build our new house, a story about a young family who follow the advice of properly trained local builders and technicians: their new home resists when the typhoon arrives.