The roof was built in two parts, utilizing two softly upward curving reinforced concrete membranes, with a space between for insulation. The sinusoidal curved ceiling was formed with wooden framework and then whitewashed. The linear, textured impression left from the timber framework emphasizes the lines of increasing curvature of the roof. Robin Evans believes that the ruled surface was integral to the roof design from the beginning, and may have been influenced by Antoine Pevsner's sculptures from welded metal rod, which Le Corbusier felt could be generalized as models for timber shuttering.