CASE STUDY

Western Pacific Case Study, Part 1

After a major typhoon passed through several Western Pacific islands in the mid 1980s, a damage survey was conducted to assess the building types hardest hit and the type of damage sustained by these structures.

Most of the building failures recorded were among small single family dwellings. Of these, most of the damage incurred consisted of roof failures. Roofs were lost due to the uplift force of the wind passing over the houses. Roofing sheets were peeled from the roof structure because of inadequate nail sizing and quantity of nails used to secure the roofing sheets to the structure below. In some cases where the roofs were adequately nailed down, the entire roofing system was blown away. This was due to a lack of adequate connection between the rafters and the walls.

Replacement cost estimates were made. Typical costs (replacement costs) ranged from $3,000 to $10,000. This replacement cost covered the replacement of the roof and associated structural damage, and the replacement of the owners’ possessions which were lost due to water damage from the heavy rains which accompanied the typhoon.

In the subsequent building program, elements were incorporated into the replacement program to strengthen the houses against typhoon force winds.

These elements were as follows:

longer roofing nails of the proper type

closer spacing of the roofing nails

bent metal straps used for connecting the rafters to the wall to resist the uplift force of the wind

shorter overhangs to lessen uplift

plywood soffit closures to lessen the uplift of the roof

The total average cost per dwelling for these improvements was $50. With an anticipated savings of thousands of dollars in replacement costs in a future typhoon, the mitigation elements were seen as a probable savings even though they added slightly to the initial cost of the rebuilding program.

In addition to the obvious monetary savings, several other non-monetary effects are also avoided. No displacement from the rebuilt house would be required for the family, no emergency shelter required, no loss of personal effects, no lost time away from employment due to the disaster, and no reliance on the aid of outsiders.

This example makes two interesting points regarding mitigation measures and reconstruction:

1. Development measures (in this case reconstruction) can effectively incorporate mitigation measures.

and

2. Mitigation measures are not always expensive. Even though there is a tendency for the cost of a building to rise as the level of safety increases, there are often simple and inexpensive ways available to strengthen many types of structures. These can be incorporated into new development programs as well as reconstruction projects to reduce vulnerability without significantly increasing cost. *

* This case study is a composite of real events that often occur.

Q. Identify two types of recovery programs that would have long term positive implications for development.

A.________________________________________ __________________________________________ __________________________________________