Wall Space

Question: What is a wall?
  Answer: A wall is a permanent vertical construction with a continuous surface except where pierced by doors, or windows. Walls define the physical limits of an area. They can subdivide interior space with partitions or exterior siding of a building. Walls may support floors, and roofs. - 155

Question: What are walls made of?
  Answer: Walls can be made from masonry, wood, plaster, brick, stones, metal or other building materials. - 156