Ban's interest in using existing materials aligned with his minimalist ideology. There was never a question of manufacturing a different paper material as current technologies such as waterproofing films, polyurethane and acrylic paints can be used to improve its material properties."pg31" In the design of "The Paper Dome" in 1998, paper as an innovative building material had to meet the rigorous construction codes, so a great deal of structural engineering data was submitted to the government. In this project straight paper tube joists were connected by laminated timber joints. Although the joints were expensive, the low price of the paper tubing made for an inexpensive overall budget."pg32" In addition, the paper tubes were waterproofed with liquid urethane to minimize expansion and contraction due to humidity variances found in Osaka-Cho Japan."pg93"