Hardwoods and screws: Ironwood in the Tri Hita Karana Tower

Located on Bali's west coast, the Tri Hita Karana Tower is a project that bridges tradition and modernity. Designed to blend effortlessly into the local context, the tower was inspired by the idea of combining ancient culture with contemporary technology, using carefully selected materials while focusing on minimising the tower’s impact on the surrounding landscape.  
 
The structure was developed based on a design by Arthur Mamou-Mani, in partnership with Global Woodtech – the company responsible for overseeing the engineering and construction – and supported by the municipality of Nuanu. The collaboration resulted in a structure that now serves as a new architectural landmark for the island, integrating art, engineering and spirituality. 

The tower is a symbol of eco-parametric and circular architecture, starting with its structure made of ironwood repurposed from an old colonial bridge. This reclaimed timber was used to build the central structural elements, the staircase, floors and balustrades.  

Rising over 30 metres, Tri Hita Karana evokes the island’s ancient coastal temples, inviting the community to participate in events and ceremonies while enjoying a panoramic 360-degree view of Bali.  
 
The exterior in rattan, selected for its regenerative properties and treated with plant-based bio-epoxy, gracefully envelops the tower in a flowing form reminiscent of a river.  

The vision behind the Tri Hita Karana Tower project was precisely to create a building that respected traditional Balinese construction practices while incorporating modern techniques to ensure both stability and durability.  

Ironwood: Ulin timber selected for its strength 

To achieve this balance, Ulin timber – also known as Borneo timber or “Ironwood” – was chosen as the main construction material for the tower, precisely because of its exceptional strength and high density of 1000 kg/m³.  

This specific type of timber was selected for its resistance to water and humid climates, making it ideal for a coastal structure exposed to sea winds and salinity. When working with this material, the fasteners connecting the various structural elements must be carefully chosen to efficiently penetrate the material and create strong joints, without unnecessary delays. 

Ulin timber is commonly used in traditional constructions, for example to build longhouses, boats, bridges and funerary monuments. Not only are its strength and resilience crucial in particularly challenging environments, it also holds deep spiritual significance in the regions where it grows. Indigenous communities rely on this material to build traditional homes and tools, reflecting the strong connection between nature and culture central to Balinese heritage. In Indonesia, Ulin timber has recently found a place in contemporary architecture, too. 

Completed in August 2024, the Tri Hita Karana Tower harmoniously fits into the surrounding natural and cultural landscape, while also incorporating modern features, fully adhering to international certifications. 

Fasteners for high-density timbers 

The complex design and structural demands of the Tri Hita Karana Tower project offer a valuable technical case study, in particular with regard to the choice of fasteners and materials suitable for working efficiently even with dense timber like ironwood. 

The structure effectively requires certified, tested components that guarantee long-term performance while also allowing for quick, practical and certified connections, thus simplifying installation and delivering a strong, reliable hold. 

Solutions such as HBS HARDWOOD, the certified screw designed for use with high-density timbers without pre-drilling, the XEPOX D resin, as well as the stainless versions of KOS, ULS and STA, all proved ideal for this task. 

 
HBS HARDWOOD, installed in this case with protective timber screw cover caps, features an enlarged internal thread diameter to ensure secure tightening in the highest density woods.  
Its 60° concealed head allows for effective, minimally invasive insertion, enabling rapid tightening aided by the special diamond-shaped tip and notched, serrated thread. 

XEPOX D, on the other hand, proved particularly valuable for the screwless joints, given its certification for structural use.  

The right fastener for every timber, and every environment 
 

Timber density is not the only factor to consider when choosing fasteners; even more crucial is the corrosivity class of the timber itself, or of the surrounding environment. 

That’s why we’ve developed a new system of search filters on our website, enabling users to select the perfect fastener in just a few clicks.  

Try it out here: https://www.rothoblaas.com/products/fastening/screws, and delve even deeper into the relationship between timber and fasteners with our timber screws smartbook: https://issuu.com/rothoblaas/docs/smartbook-timber-screws-en?mode=embed

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