However, brick and masonry construction, especially vaulting, was heavy, was time consuming to construct, and required the construction of costly custom formwork. Structural clay tile offered a lighter, faster, and simpler alternative. An interlocking system of angular clay tiles that were fit together with a keystone became popular in the early 1870s, after designs by Vincent Garcin were mass produced to create flat segmented arches. This flat segmented arch, developed by Garcin, was first used in the United States at the New York Post Office, Kendall Building in Chicago, and the Singer Manufacturing Building in St. Louis, becoming the most prolific use of hollow clay tile until the end of the century. With its increased popularity, structural clay tile became one of the most popular materials for fireproofing iron and steel construction. However, its capacity for fireproofing was not fully realized until Peter Bonnett Wight invented the "tile shoe" in 1881. The "tile shoe" covered the exposed side of metal beams, fully insulating them from fire. Flat arch construction grew in popularity with the increasing number of buildings using steel and iron structural members in their design. New building code requirements for fireproofing aided in the use and proliferation of structural clay tile in skyscrapers and other large buildings. After 1910, manufactures began to test and develop stronger and more complex structural clay tile systems that worked better in compression. Greater compressive strength, found largely in the invention of the end pressure arch, allowed the material to be used in longer floor spans. However, as reinforced concrete grew in popularity as a cheaper and less complex alternative, structural clay tile use in floors and roofing declined. Increasingly, clay tile was used inside concrete flooring to make it lighter, or as centering/formwork for concrete construction. With the rise of reinforced concrete flooring and metal decking, structural clay tile fell out of popularity for use in horizontal applications. While the use of structural clay tile in flooring and roofing declined, its use in walls enjoyed popularity into the 1950s. Wall tile blocks continue to be manufactured, but specialty tile units often require custom commissions. Clay tile arches are no longer manufactured and due to a lack of skilled artisans to lay the arch systems, they are never replaced. Side pressure arch construction, the first method used in tile floor arches, is composed of hollow tiles laid parallel to I beams. End pressure arch construction is composed of hollow tiles laid perpendicular to I beams. This method enjoyed popularity after it was discovered to be fifty percent more efficient than side pressure arches.