Much of the vaulting in the temple is made using thin masonry timbrel or Catalan vaults. This technique, common in traditional construction in Catalonia, consists of two or three layers of overlapping tiles or flat bricks which are woven together with fast-setting mortar to create a highly resistant structure. Gaudí used Catalan vaulting to construct hyperboloids and paraboloids. Decorative elements made from green and golden glass are set in the spaces left by the lines of tiles, representing the leaves of the trees represented by the vaults and columns.