The one element carried through Tadao Ando's structures is his idolization of the reinforced concrete wall. The importance given to walls is a distinct departure from Modernist architecture. They are usually made of 'in-situ' poured in place concrete. Considerable care is taken to see that the walls are as perfect as technique will allow. These walls are thick, solid, massive, and permanent . The main reinforced concrete shell of the Church of the Light is 15 inches thick.
"In all my works, light is an important controlling factor," says Ando. "I create enclosed spaces mainly by means of thick concrete walls. The primary reason is to create a place for the individual, a zone for oneself within society. When the external factors of a city's environment require the wall to be without openings, the interior must be especially full and satisfying." And further on the subject of walls, Ando writes, "At times walls manifest a power that borders on the violent. They have the power to divide space, transfigure place, and create new domains. Walls are the most basic elements of architecture, but they can also be the most enriching."
"A smooth surface was achieved by adopting a dense engineering quality mix with a slump less than 15cm (6in) and by ensuring thorough vibration with a minimum cover for the reinforcing bars of 5cm (2in) to avoid weathering problems and staining. The density of the concrete results in a glass-like surface that registers the different qualities of light, and tends to dematerialize it. Because Ando's concrete is so precisely wrought, and so smooth and reflective, it produces an illusion of a taut, textile surface rather than presenting it as a heavy earthbound mass. Ando has his own teams of expert carpenters to make the formwork who compete against each other; even so, his walls contain imperfections and are uneven." ("Church on the Water, Church of the Light" by Tadao Ando and Philip Drew)