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Kayu Ulin
BUILDING MATERIALS & CONSTRUCTIONintermediate
Definition
Ironwood (Eusideroxylon zwageri) — one of the hardest and most durable tropical timbers in the world, found in the lowland forests of Kalimantan. Kayu ulin is exceptional for structural use in wet or marine environments: it hardens rather than decays when exposed to water, making it the traditional material for pile foundations, bridge piers, and the stilt structures of riverine rumah panggung in Borneo. Its exceptional density makes it resistant to marine borers and termites.
Example
Traditional longhouses (rumah betang) of the Dayak people in Kalimantan use kayu ulin for their stilt foundations and floor structure — piles that may remain in direct contact with soil and water for a century or more without significant decay.