Expansion Joints

Tiling over expansion joints in concrete is not a recommended practice, for a number of reasons. The thermal movement of the concrete will be transferred through the tiles, and may cause them to lift, crack or become loose. To tile over areas where expansion joints have been placed, it is recommended that you place a flexible membrane over the top of the joint to accommodate thermal movement in the concrete without transmitting it through the tiles. When tiling the area, it pays to use flexible grout and adhesives that can handle the movement of the concrete slab caused by thermal expansion and contraction. 

Concrete expansion joints are usually placed prior to the pouring process, as this allows the slab to be poured and dried with the expansion joints in place. Attempting to cut spaces for expansion joints after the concrete has been poured is a far more labour intensive process that may produce a less effective result. Without expansion joints in place, the slab could have been impacted by thermal expansion or contraction during the drying process. 

Concrete expansion joints are gaps placed at designated points in the cement slab to account for expansion and contraction due to changes in temperature. Expansion joints prevent random cracking of the concrete slab by absorbing the stress of the slab’s natural expansion and contraction. An expansion joint should be placed at regular intervals throughout the slab, or at points where the concrete meets another structure.

Expansion joints are a necessary finishing material in a wide variety of concrete applications. They help to control the locations and ways in which the concrete eventually cracks, accommodating the natural movements of the slab during thermal expansion and contraction. Multiple expansion joints are a mandatory inclusion in large concreting projects, forming a legal requirement of some building codes and construction standards.