Are Expansion Joints Really Needed?
To be accurate, what you are looking at is not really the expansion joint. A joint is a gap between structural elements. That gap runs from the foundation, upwards through the structural beams supported by double columns, the roof deck, and roof system. The roofing industry provides expansion joint covers. Beams are supported independently on each side of the joint, and the deck is discontinuous as well. The purpose of the structural expansion joint is indicated by its name: It allows for expansion, contraction, or even seismic relief so that the structures on each side of the joint can move independently. Large roof structures extending over acres are a fairly new development. Massive poured concrete buildings are rare today because of the associated costs of foundations to support the weight, dead weight of the deck and supports, and labor involved. If a concrete deck can be poured as a monolith, there is no need for joints (just in the roof system). However, for the lightweight stee
