When re-grouting tile, how much old grout should be removed?

Removing half of the depth of the old grout is typically recommended when re-grouting tile. This approach effectively prepares the joint to receive new grout without compromising the integrity of the surrounding tile. By taking out approximately half, you create sufficient space for the new grout to bond effectively, which enhances adhesion and helps to prevent future cracking.

In practice, this means that the new grout will have a solid base on which to adhere. If too little grout is removed, the new grout may not bond well due to insufficient space, leading to deterioration over time. Conversely, removing all of the grout can risk damaging the substrate or the tiles themselves, leading to unnecessary repairs. This balanced approach ensures a durable and aesthetically pleasing finish.