2V - 3V - 4V

Platonic solids are approximations to the sphere and only the icosahedron is very close, but to make a large structure from it would require very long struts. One way to proceed is simply to subdivide the triangles in one of the regular platonic solids, and this is how a geodesic dome is constructed.

The names, “2V”, “3V” and “4V” refer to the number of subdivisions that are made to the original triangles in the icosahedron before they are pushed out to the surface of the sphere.

THE STRONGEST - THE LIGHTNESS

The more subdivisions of one face of a given diameter icosahedron, the more numerous and smaller are the triangles, and the closer you get to a sphere.
If the structure is completely composed of triangles, it can be made completely rigid, even if the individual joints are not.
When force is exerted at any point on the sphere, all members of the grid, combine to more or less, equally absorb this force.
The economy of the sphere combined with the strength of the geodesic grid, makes this type of dome, the strongest, the lightest, most efficient building system ever devised.

3 in 1

During the design stage of The Nam Kan National Park Visitor Center more aspects in term of material saving have been adopted.
First to notice is that 3 different dome structures have been used. The main dome is a 4V, the 2 kitchens on north side are located in a 3V dome and the smallest kitchen on the east is a 2V. If on one side using only one typology would have made easier, on the other side using 3 different types allowed to have the most convenient variation compared to the struts length, the material available and the volume of space needed.

STEEL HUB CONNECTORS

The wood used for the structure are logs of rosewood seized by the national park forest guards and already cut in 2 meters size with only few pieces left longer. The size of the log was one of the reason in first place to choose a geodesic structure over others.
Into detail, a 4v dome uses 250 struts of 6 different lengths. Since a 16m diameter structure was planned, the struts lengths can be mathematically calculated and vary from 260 cm to 202 cm. With the wood available became necessary to design custom steel connectors that allowed to use shorter struts than the length needed. All the struts were attached to 91 steel connectors of 4 types and able to gain 20 cm on the theoretical length.

COVER

The cover is made with fiber cement panels installed on all the surface offering a good compromise in term of thermal insulation, fire and insect resistant, humidity acceptance and low in carbon footprint. A non-toxic water based polyurethane waterproofing membrane, highly elastic and UV-resistant has been applied on top. To minimize the impact of the structure in the local community and further reduce the solar radiation absorbed, the whole structure was covered by around 15000 rattan palm leaves locally prepared giving a salutary job to around 12 families every 2 years.