What are Ralph's reasons for wanting to build shelters in Lord of the Flies?

Ralph decides to build shelters so the boys have civilization on the island. 

Ralph does the best he can to create order on the island.  He wants to be a good leader.  He was elected because he blew the conch, and that created a sort of mystique the other boys respected.  He was a connection to the adult world, drawing them together.  However, he was never really able to get much done.  His goals were to get a signal fire going and tended and shelters built.  Neither goal was well-accomplished. 

Ralph wants to recreate civilization.  He wants rules and order.  He is worried about bad weather, and what will happen to the boys then.  He decides that they need to build some shelters off the beach. 

Ralph is also concerned because so many of the little kids get afraid at night.  He thinks the shelters will make them feel safe, reminding them of the comforts of home and making them feel protected from the beastie. Building something also gives them an occupation and keeps them busy.

Building the shelters is a difficult task.  Ralph cannot get the boys to follow directions and accomplish any goal.  The younger children do not work, and the older ones don’t listen.  Nothing gets done.

“They’re hopeless. The older ones aren’t much better. D’you see? All day I’ve been working with Simon. No one else. They’re off bathing, or eating, or playing.” (Ch. 3) 

Ralph’s failure to get the shelters built is symbolic of his failure at leadership in general.  Ralph is not able to get the children motivated.  He can’t make them listen. It is symptomatic of a larger problem.