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Expansion Joints

Expansion joints are a part of construction but they are rarely thought of by the average home owner or renovator.  What exactly are they are why are they important?  Read on to learn more.

What are Expansion Joints?

Building faces and concrete slabs contract and expand according to the temperature in the air – expanding in the heat and contracting in the cold.  This is called thermal expansion and this movement needs to be accounted for.  Without expansion joints, structures would crack underneath the stress.  Expansion joints are specifically designed to allow the building to move safely during thermal expansion periods.

Be aware however that a control joint and an expansion joint is not the same thing, even though the terms are sometimes used interchangeably.  A control joint, simply speaking, is a groove cut into the surface of the concrete that allows some cracking to occur in the joint without being readily visible.  An expansion joint is placed between two separate pieces of concrete or between concrete and another material.  This expansion joints allows for movement of the two pieces.

Types of Expansion joints and Materials Used

Expansion joints can be used in the following areas of construction:

• walls
  
• floors
  
• hard or brittle floor finishes

Expansion joints are most commonly used in floors, to stop cracking of concrete slabs, and also to protect hard or brittle floor finishes such as stone, terrazzo, and tiles.  In the latter, expansion joints control the movement in these finishes while still maintaining a complete structural and adhesive integrity of the floor finish.

If a more sealed joint is required, seal joints can be used.  These are waterproof, and stop germs and debris from accumulating.  Seal joints can be customised to fit flush with any floor covering.

Some of the different materials that can be used in expansion joints include:

• stainless steel
  
• luminium
  
• brass
  
• polyethylene
  
• rubber
  
• cork fibre
  
• elastomeric polymers
  
• PTFE

In some cases, being able to choose your cover plate joint means that you can extend your design options while still maintaining the properties of the expansion joint.

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