How to replace grout behind tile?

[m_ee_e]

 hi, I am looking at trying to fill this gap behind the tiles in the bathroom, what should I use

[MitchellMc]

Welcome to the Bunnings Workshop community @m_ee_e. It's fabulous to have you join us, and many thanks for your question about filling a grout gap.

You could fill this area with grout, or alternatively, since there's been a bit of movement that has caused the grout to crack, you can use silicone, which is flexible. Using silicone will prevent cracking issues in the future.

Here's a helpful guide: How to apply silicone sealant.

Please let me know if you have any questions.

Mitchell