A safe house must be based on a strong foundation and therefore it must be given primary attention. Problems with foundations not properly designed lead to unequal settlement, cracking of walls and floors, and structural weakness. To resist outside forces, a house needs a coherent and simple structure. House structure is like the skeleton to the body. If it is strong, it protects the whole house. Walls must be joined to the roof. Walls and roofs can strengthen each other if joined properly. Walls also must be joined to the building structure. Walls should be supported by the columns, and need to be connected to them. Roof trusses must be flexible but strong enough to enhance safety. Walls and roofs need bracing against lateral movement. Drainage plans are essential to good house design. The design should carefully consider whether the house needs to be elevated to safeguard its contents from flooding.