Such a houseboat is about 90 to 100 feet (about 20 to 25 meters) long and about 15 feet (about 5 m) wide at the middle. The hull is made of wooden planks that are held together by ropes of coconut fiber; the usual wood is 'Anjili'. The roof is made of bamboo poles and palm leaves. The exterior of the boat is painted with protective coats of cashewnut oil.

Unbelievable as it may sound, not a single nail is used in the making of a Kettuvallam. Jack wood planks are joined together with coir rope and then coated with black resin made from boiled cashew nut shells. The materials that go into the making are all local and Eco friendly bamboo poles, coconut fiber ropes, bamboo mats, coir carpets etc. These traditional country boats were used as the mode of transport in the early times from the isolated interior villages to the towns.