Batak House (Jabu)

The Batak are a group of peoples of North Sumatra, Indonesia, whose traditional houses are among the most dramatic in Southeast Asia. The Toba Batak house (jabu, also called rumah bolon) is dominated by a huge, steeply pitched saddleback roof with projecting gables, while Karo Batak houses rise in tiers under great hipped roofs.

Toba Batak roofs

• Form: a large, steeply pitched saddleback roof. Rafters angle outward from the wall plate to produce the curve, and sharply projecting triangular gables overhang the house on all sides. The front gable reaches further than the rear.
• Structure: there are no internal roof trusses. Large longitudinal beams called labe-labe, at head height, carry the roof, and diagonal ties run from them to the gable ends instead of horizontal battens.
• Space: the open roof creates most of the interior volume. A flat timber ceiling over the front third of the living area forms an attic for heirlooms and sometimes shrines.
• Decoration: the front gable is carved and painted in red, white and black with suns, stars, cockerels and geometric motifs; the rear gable is plain.
• Covering: roofs were traditionally thatched.

The rice barn (sopo) follows the same form, with grain stored inside the roof, carried on six large pillars over an open working and sleeping platform.

Karo Batak roofs

Karo houses (siwaluh jabu) have hip roofs rather than saddle roofs, sometimes up to 15 m (about 49 ft) high. Variants include:

• rumah beru-beru - a basic hip-and-saddle roof;
• si empat ayo - four gables, made by crossing two saddle roofs at right angles;
• rumah tersek - a double-storeyed roof, with a saddle roof over the lower hipped part, improving ventilation and letting cooking smoke escape;
• anjong-anjong - a miniature house set on top of the roof as decoration.

The roof is thatched and bound with ijuk, fibre from the sugar palm (Arenga pinnata), without nails or screws. Painted interlaced triangles called ajo decorate the gable, and buffalo horns are mounted at the roof ends.

Comparison

Unlike the Minangkabau rumah gadang, whose curved roof sits on conventional walls, the Toba roof itself forms most of the living space. Both belong to the Austronesian tradition of raised houses with steep, heavy-gabled roofs.