By: Jose Santos
During a facade restoration project, it’s very important to consider the different ways of distributing the loads or weights on the structure, and how this effects the structure and the materials it is composed of. It is also necessary to consider how the materials used are affected by the surrounding environment. Factors such as humidity or extreme temperatures cause what is known as tension in the internal resistance of each material. Expansion joints are used to control the movements that generate this tension.
An expansion joint is an element that allows relative movements between two parts of a structure. All construction materials have a coefficient of expansion. This coefficient is a function of temperature variation. When the temperature rises, the material expands, and when temperature decreases, the material contracts. Therefore, it’s necessary to provide areas where these large stresses can be absorbed. Expansion joints are installed to do that just that. By absorbing the stresses on a building, they help to prevent cracking in brick, stone, stucco, mortar joints and all other façade materials.
The most common and recognizable symptoms of the lack of expansion joints are extensive vertical cracks in the face brick, crumbling mortar joints, crumbling brick masonry, and bowing bricks. The design professional overseeing a restoration project will provide the locations of expansion joint installation. These typically include building corners, parapet walls, door edges, window openings, and areas of change in wall thickness or height. For aesthetic reasons, the widths of expansion joints are typically the same as the widths of the mortar joints. The location of and distance between expansion joints can vary. For example, expansion joints at a parapet wall are typically less than 25’ apart, while at a corner rebuild, expansion joints are installed no more than two or three brick lengths from the corner of a building.
The correct design and placement of expansion joints will decrease damage and deterioration to building materials caused by loads and environmental conditions. Additionally, proper installation of expansion joints will extend the life span of an exterior façade.