The family's means of building their first house depends on a sound understanding of nature. First, the family choose a big tree with branches at a great height, so that a rope ladder could be strung from the branches. For temporary shelter, a sailcloth is slung over this tree to make a sort of tent, but this is only the first step. The family intends to find wood to build a house with, and possibly some rod to build a ladder with. Ernest finds some bamboo in the sand, and the family cut these to lengths of five feet and bring them back to the tree.
Using geometric calculations, they determine that they should build their house thirty feet up in the tree. They build a ladder and fix it to the ground with stakes. Then they fashion a pulley so that materials can be brought up into the tree.
Later, more wood is collected from the beach for building, and these planks are pulled up into the tree to be arranged as a "smooth solid floor." The sailcloth is then brought up to be slung over the highest branches in the tree and nailed down to the platform of planks. This makes a sort of treehouse or "nest" high up in the tree, enclosed on three sides by the sailcloth and the tree trunk, with the front left open to allow access down the ladder and to allow the sea breeze to blow in.