An expansion joint is a structure used to relieve stress on the building materials. Stress usually arises from building or structure movements caused by the wind, temperature changes and other events. It is used on walls, roof, floors, bridges, planters, decks and plazas among many others. A joint is used to bridge the gap as well as to restore the functions. Some functions include waterproofing, sound proofing, fire proofing, roof membrane and air barrier among many others.
Expansion joint is also called movement joint. This is because movements in the building result to expansion and compression of the joint. For instance when it is hot, the building will expand causing the expansion joint to compress. And when it is cold, the building cools down causing the movement joint to expand. The expansion and compression are the reason it is called a movement joint. It is the element that is under the most stress in the entire building.
Expansion joints can either be metallic or rubber. Metallic joints are usually used to prevent damage caused by thermal expansion, pressure, vibration and other mechanical forces. They are used to cater for internal and external pressure, weight of the structure and movement caused by external restraints.
Rubber expansion joints are flexible connectors made from natural or synthetic fabrics. They have metallic reinforcements that provide stress relief. They are used in plants to cater for angular, torsional and lateral movements. The use of expansion joints in plants helps prevent vibration, noise, shock, load stress, pressure pulsation, corrosion, abrasion and equipment movement.