Grout cracks for a number of reasons, including:
Shrinkage: If the grout contains too much moisture, or if the joints are too wide, the grout will experience substantial shrinkage as it cures, and it may crack. If there is a good bond with the tile, the crack will occur down the center of the grout line. If there is a weak bond, the crack will occur at one of the edges between the grout and tile.
Insufficient support: If the tile is adequately supported, perhaps on a soft, flexible wood floor, the flexing in the support will create stresses in the tile and grout. This can crack the tile, crack the grout, and even cause the tile to become de-bonded and loose.
Freeze-Thaw Cycles: If the tile is outside in a cold climate, water can penetrate below/between the tile during warm months. This water can then freeze during cold months. As the water expands, it creates stresses that can crack the tile, grout joints, or de-bond the tile.
Mechanical weathering: Over time, grout joints can become worn or loose from basic weathering (rain, wind)
The good news is that the grout can be repaired. The specific remedy will depend on the cause of the cracking. Obviously, if your floor is insufficiently strong to support the tile, simply repairing the joints will address the underlying problem and you’ll experience cracking again in the future. The best repair for cracked grout joints is generally to grind out the mortar and replace it. There are many professionals who specialize in this type of work.
For more knowledge about ceramic tile sealing, please contact KASTAR!
