The tops of the piles are notched for the longitudinal and transverse beams that support the upper structure. The remainder of the sub-structure is assembled in-situ. The transverse beams are fitted into the notched piles, and then notched to fit the longitudinal beams. Side panels, which are often decorated, are then formed on these main horizontal beams. The distinctive curved roof shape is obtained through a series of vertical hanging spars supporting upwardly angled beams. A vertical free-standing pole supports that portion of the ridge pole extending beyond the ridge purlin. Bamboo staves bound with rattan are assembled transversely in layers and tied longitudinally to the rafters forming the roof. The under roofing is of bamboo culm. Wooden boards laid over thick hardwood joists form the floors. Nowadays, zinc roofing sheets and nails are increasingly used