North Nias houses have an oval floor plan, rows of diagonal bracings (X form) in the substructure and a huge hat like roof. Central pillars lead from basement to ridge pole. The façade is all around the house.
In Middle Nias houses have a rectangular floor plan, slanting sidewalls and an oblique front façade, which is often decorated with carvings and/or colour. In the substructure v-shaped diagonal bracings are significant. Layouts of Central Nias houses can vary from rectangular to cross-shaped. The hybrid typology of these houses has not yet been fully examined. Research on its origin and influences on North- and South Nias types will form an important part of our project.
Houses of South Nias have a rectangular floor plan, straight load bearing sidewalls and a slanting front façade. Significant is the v-shaped diagonal bracing in the front façade and the very high steeply pitched roof. Houses are built side by side in a row. So the house has just one front façade with open louvers and decoration.
All house types are entered from the side, the entrances sometimes being very creative annexes. In former times the houses were entered from below through bottom flaps. In the core of the house used to be the fireplace. Under the colonial rule of the Netherlands a decree ordered that kitchens had to be placed in an annex outside the house. Nowadays all kitchen and sanitary facilities are situated in these annexes. For the oval shaped North Nias houses the annex construction is quite difficult. No typology has yet evolved for these recent building parts.
Very significant for all Nias houses are the window flaps in the roofs. This kind of opening is peculiar to the island of Nias and cannot be found elsewhere in the Archipelago of Indonesia.
Fig. 1:North Nias house, Sihare'o Siwahili
TRIPARTITE STRUCTURE
The construction of the buildings has evolved reflecting the tectonic situation under the steady threat of seismic shocks. As in many other types of houses in Indonesia, we also find in all Nias house types a vertical zoning of three different levels, each level having its own structural system and serving a different function. The tripartite structure refers to a spiritual differentiation: the underworld, the present world and the upper world of the ancestors.
The ground floor represents the underworld. This originally open space is only used for storage and for animals. The living area allegorises the present world, the place where every day life takes place. Ancestors and gods have their space in the roof as the place of the over world.
Besides the spiritual meaning of the tripartite zoning this construction idea is responsible for the earthquake resistance of the buildings.
Fig. 2: South Nias houses, Bawomatalou
The houses rest on a structure of vertical and oblique posts which are placed on slabs of stones. Vertical posts and X and V bracings are the elements of this substructure. The threedimensional structure offers great resistance and has the required elasticity because it does not settle in the ground. The separation of the house from the ground is the most important concept for earthquake resistant building in traditional form.
The first floor - the living floor - is in itself a very stable boxlike structure. Even if the substructure collapsed, the box persists. In the 11 villages we visited, nobody was killed during the earthquake of 28th March 2005 due to the breakdown of a traditional house.
The living floor is separated into public, private and transitional spaces either by wooden walls or changes in the height of the floor. This element to organise space is most elaborate in South Nias houses and will show up also on the village level.
Large openings over whole front facades provide good ventilation. They enable the inhabitants to overview the neighbourhood. Depending on the distance to the opening a good control of contact and visibility is possible.
Houses are hardly furnished, the inhabitants belongings stored in chests. The most important piece of furniture is a long plank below the louvers, which the tenants use as a bench.
Fig. 3: Interior of the front room of a South Nias house
The steeply pitched roofs are a notable feature of Nias houses. The roofs of the chief's houses, called "Omo Sebua" can reach up to 20m. Still most roofs are covered with palm leaves, although the use of tin is getting more popular.
The light multi-storey roof-construction is resting on 2 main pillars in the North and Middle Nias type, and on sidewalls in South Nias. The steep sloping roof zone is a very light 3d structure. Minimising material is the most important issue of this intelligent construction. Furthermore, the large overhangs protect the wooden connections from rain and provide additional space outside.
MATERIALS AND DETAILS
For the traditional house only local grown plant material was used. Even nowadays the use of metal even for the renovation of traditional houses is avoided. The wooden beams are jointed using elaborate mortise and tenon connections. They are very flexible and don't break in case of earthquakes. Loosened connections can be fixed easily.
Different kinds of wood are used according to the position within the construction. Noticeable are the posts of a very slow growing hardwood called “Manawa Danö” which is used in the North Nias houses. As this wood is very hard and trunks are built in the construction as they are grown, the posts of the substructure have very different shapes and give the substructures very interesting designs.
For the interior of South Nias kings houses huge plates of ebony have been used being most impressive. With the beginning of extensive cultivation of land for plantation the growth of building timber declined.
Ebony was grown on the island of Telo but also here it is getting scarce. Apart from wood, palm leaves and bamboo are still used for the roofs and coconut fibres are used for binding.
Natural stones are used for the base underneath the posts in the substructure of the houses. For the pavement of the roads especially in South Nias slab stones are laid very exactly. Similar techniques and designs of carving are applied to wood.
South Nias houses have the fine decoration inside the house. The wooden carvings show the status of the owner. Especially the Omo Sebua have numerous fine carvings.
Natural stones are used for the base underneath the posts in the substructure of the houses. For the pavement of the roads especially in South Nias slab stones are laid very exactly. Similar techniques and designs of carving are applied to wood.
South Nias houses have the fine decoration inside the house. The wooden carvings show the status of the owner. Especially the Omo Sebua have numerous fine carvings.
Fig. 4: Omo Sebua in Hilinawalö Mazinö, South Nias
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