Building expansion joints are often required to allow for various types of building movement. These joints cut completely through the building to allow the segmented pieces to move independently from each other. The joint goes through all portions of the building, including the exterior walls and roof. It is important to use an expansion joint cover to bridge the joint, which keeps things like water and debris out to allow the building to move as designed. The exterior building expansion joint can cause major issues if it’s improperly installed or neglected in the planning phase.
Proper planning begins with understanding how both the joint and the cover should function. Determine the nominal joint size and its movement in order to choose the best cover type. For the most part, factory manufactured covers should be used on joints 1 inch and larger, while smaller joints may be closed off with backer rod and sealant or pre-cured silicone sheet. The larger manufactured covers can be made weathertight in a variety of ways. Selection of exterior wall covers can include compression seals, pre-compressed foams, rubber and rail systems and metal covers with moisture barriers.