Expansion joints, also known as building expansion joint covers, it is a vertical structure separation designed to prevent stress on building materials from damaging the building,the stress is caused by building movement induced by:

1. expansion / contraction caused by temperature changes,

2. sway caused by wind, etc

An expansion joint separates the building components above foundation such as walls, floors, roofs (except wooden roof) into several separate parts,so that the building can expansion or contraction in horizontal direction.

 

A construction Joint is not really joint.In most structures, it is not possible to pour all of the required concrete at one time.The volume of concrete, structural limitations and time limitations make it necessary to discontinue placing concrete at some point, to be resumed later after the concrete has hardened .So the engineer will specify the place to put a break in the pour. The plane of separation between the placements is called a construction joint.

 

Like Expansion joint,a settlement joint is also a vertical structure separation designed to prevent stress on building materials from damaging the building,but the stress is caused by:

1.unequal compression of its foundations because of different height and structure,

2.building built in different soil and different characteristics of the foundation,etc

So a settlement joint separates the building components from foundation to roofs，this is main difference between Expansion joints.