Expansion Joint – The Right Material Is Very Important.
Expansion joints also referred to as movement joints mimic such parts in our bodies as they expand and contract as needed. These movements contribute to a structure’s overall stability. They work in bisecting a structure, like a building, and creating a gap. The gap is then filled to restore the building and to double its ability to withstand physical traumas. They are also used on construction sites to counteract seismic activity as well as help secure the structure while other parts are built around it. They protect against strong winds, dangerous temperatures, and other physical occurrences that could affect the strength of a building and its durability.
Often, these gaps are filled with an Expansion Joint System to fill in the void to ensure walkability, a complete building enclosure, waterproofing, and general serviceability of the structure.
There are many reasons expansion joints are required such as:
- Structure Size / Length
- Structure Shape or Irregularities
- Isolation of Dissimilar Building Classifications
- Fire Separation
- Thermal Movement
What you need to know!
There are many different types of systems for accommodating movement gaps in structures. Expansion joints occur through all parts of a structure to provide complete separation – through floors, walls, ceilings, and roofs (interior & exterior).
- Joints are generally not required at on-grade floors
- Systems may or may not be waterproof
The size of the gap should be as small as possible to fit the design movement, and the size of the expansion joint system needs to accommodate the full range of expected movements. For example, a gap may grow and shrink seasonally due to temperature changes; the joint system needs to stretch to fill the widest opening but it also must not buckle when the system closes to its smallest size. Expansion joint systems also may need cover or protect fire-stopping systems.
So, Who will help you?
The entire project team needs to work together to ensure success. To start, the lead Architect or Engineer determines the style of joint system and the Structural Engineer determines locations of gaps. The Structural Engineer then provides the anticipated movements and minimum gap sizes to the construction team. Often, a full range of movements for an installation temperature need to be provided on the Construction Documents to clearly express the requirements of the system’s movements.
The Contractor then reviews this information and engages the joint system manufacturer or vendor to recommend the size of system appropriate for the expected movements. It’s often helpful to have the Engineer verify the selected system for conformance with movement needs.
The Dos and the Don’ts…
After taking all of these items into consideration you will be well on your way to successfully incorporating expansion joints into your design!