Restoration of the Sistine Chapel frescoes smoke and exhaust fumes of the city, being "much dirtier than the ceiling proper". The building was a little unstable and had already shifted considerably prior to Michelangelo's work of 1508, causing cracking of the ceiling, the crack in the "Judith" pendentive being so large that it had to be filled with bricks and mortar before painting. The upper part of the ceiling provided Michelangelo an irregular surface due to cracks and water seepage. Continued ingress of water from the roof and from unroofed exterior walkways above the ceiling level had caused seepage which carried down salts from the building
Sistine Chapel three to get the width and by two to get the height. Maintaining the ratio, there were six windows down each side and two at either end. Defined proportions were a feature of Renaissance architecture and reflected the growing interest in the Classical heritage of Rome. The ceiling of the chapel is a flattened barrel vault springing from a course that encircles the walls at the level of the springing of the window arches. This barrel vault is cut transversely by smaller vaults over each window, which divide the barrel vault at its lowest level into a series of large