Streamline Moderne is a horizontal style. In the overall form of the building as a rule, and always in the main elevations, horizontality prevails, with vertical features (if employed at all) reserved for the entrance. Secondly, it is a style of curved surfaces - curved end walls, curved corners, curved bays, and cylindrical projections. Thirdly, it is a style quite without ornament, apart from stringcourses and other trim emphasizing the horizontality of the design. In larger buildings the upper stories are often set back. Roofs are flat and parapeted. The parapets are often surmounted by pipe railings, producing a nautical effect that may be intensified by pipe railings on balconies and outside stairs, by round windows like portholes, and even by imitation rivets. Walls, brick or concrete, are usually plastered. Glass block is much used for translucency and textural contrast.
Whiffen, Marcus. American architecture since 1780: a guide to the styles. N.p.: The MIT Press, 1969. Print.