In general, the construction materials used on the Sagrada Familia are the ones suggested by Gaudí and which were used on the part of the temple he oversaw the construction of.
The stone used for the bell towers on the Nativity and Passion facades is sandstone from Montjuïc in Barcelona. Due to the scarcity of this exact type of stone (the Montjuïc quarries were closed several years ago and the stone is only obtainable from demolished buildings), other sandstones and granite have been used for the windows and parts of the towers and roofs. Reinforced concrete, which Gaudí used for the pinnacles on the Nativity facade, has been used in accordance with his instructions on the construction of the naves.
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.
Today, materials are applied using techniques offered by modern construction technology. Stone is cut using computer controlled systems, as are the wooden or metal, even polyester, fibreglass or polystyrene, frames and shuttering used for reinforced concrete.
Finally, mention must be made of present-day ancillary equipment (metal scaffolding, tall, powerful cranes, and computer-aided redesigning systems) which have become indispensable tools for carrying out construction with precision and efficiency, as well as the procedure of pre-mounting large stone pieces, frames or shuttering on a large site on the outskirts of Barcelona.