Essays on the Marshallese Past Low technology reduction of damage to roofs and walls against strong winds

The passing of the tropical storm "Zelda" in late November 1991 and of the typhoon "Axel" in early January 1992 has once more shown that the islands on the atolls of the Republic of the Marshall Islands are very vulnerable to typhoon impact caused by storm-driven waves and wind action.

It is now time to pool all available resources to ensure that damage in future occasions of typhoons will be less than the damage incurred this time. One of the great, largely untapped resources the Republic of the Marshall Islands has at its disposal are the knowledge and the "appropriate technology" skills which the old Marshallese still possess, and the historic evidence, showing how the German and Japanese Administrations coped with the matter.

In this chapter we will have a look at the way the Japanese pre-World War II administration attempted to typhoon proof their houses. All these houses were wooden structures set on a concrete platform.

Protecting the roof

In order to typhoon-proof their roofs, the Japanese ensured that the roofs were well built with strongly reinforced and well connected roof trusses. In addition they provided anchor points, with which the roof could be tied down to the ground, not unlike a tent. Two options exist:

• To include the anchors in the foundations of the building when the building is being constructed (figure 1). Here one would place between four (one at each corner) and eight iron anchor points into the concrete foundation when cast. One option is to utilise rebar with one end bent into a full loop (figure 1).
  

  Figure 1

• The other option is to retro-fit existing structures with anchor points set outside the foundations. The way to do so would be to dig a large hole, about 2 x 2 x 2 feet and set in a a rebar with end bent to a full loop, and fill the hole with concrete (Figure 2). These anchor points should be heavy enough to withstand substantial wind pressures.
  

  Figure 2

In both cases a second set of anchor points would be attached to the roof trusses. These would either be imbedded in the wood, or would be attacjed to the trusses by a series of well bolted band irons. In case of an impending storm then, guy wires, or strong ropes could be strung between the anchor loops at the roof and the ground, thus tying the roof to the ground.

There is an option which can be utilised for these houses which do not possess roof trusses strong enough to allow for the installation of iron anchors: In this instance, in case of an impending storm, a strong rope can be anchored at one ground anchor, thrown over the roof of the building, and tightly tied to the other ground anchor.

This trick was utilised by the Japanese when they built their administrative structures in the 1920s and 1930s throughout Micronesia. Such anchor points can be found in many old Japanese foundations.

Protecting the walls

The Japanese also utilised another method to prevent that the houses would lift off the foundations. When the foundations were cast, the Japanese cast in strong long bolts, which protrude for about 4-6 inches above the foundation The wooden sleepers, on which the walls would be erected, would be sat upon these bolts and fastened by adding a large washer plate and a nut.

In Djarrit, Majuro Atoll, there is still a Japanese building, erected as part of the seaplane base, which still stands and which - 50 years after construction - provided ample evidence for the strength of the building method employed.