The $12 regrout fix (no tiler needed)

You will need

• Grout rake or oscillating multi-tool with grout blade · Grout rake ~$8 at Bunnings (aisle 8, tiling section); multi-tool blade ~$15 if you already own a multi-tool
• Selleys Wall Tile Grout (pre-mixed, white or grey) · ~$12 for 1kg tub at Bunnings — matches most standard bathroom grout colours
• Grout colour matching card · Free at Bunnings tiling section — hold against your existing grout before buying
• Old toothbrush or stiff-bristled brush · From your kitchen drawer or $2 at Woolies
• White vinegar in a spray bottle · ~$2 at Woolies — cleans and preps joints without damaging tiles
• Grout float or firm rubber squeegee · ~$8 at Bunnings — spreads grout cleanly into joints
• Two clean damp sponges or microfibre cloths · $3–$5 at Woolies or Bunnings

Step 1

Rake out the damaged grout

Use the grout rake (or multi-tool blade) to scratch out the cracked or crumbling grout to a depth of at least 2–3mm. Work slowly along each joint — you want to remove the loose stuff without chipping the tile edges. Vacuum or brush out all the dust and debris when done.

Step 2

Clean the joints thoroughly

Spray white vinegar into the open joints and scrub with the old toothbrush. This removes soap scum, mould and residue that would stop new grout bonding properly. Wipe dry with a cloth and let it air for 20–30 minutes before moving on.

Step 3

Press in the new grout

Scoop a small amount of Selleys grout onto the float and press it firmly into the joints at a 45-degree angle, working it in well. Go over each line two or three times to make sure there are no air gaps. Don't worry about the mess on the tile face — you'll clean that shortly.

Step 4

Wipe back and shape the joints

Wait about 10–15 minutes until the grout is firm but not rock-hard (it will look slightly matte). Use a damp sponge to wipe diagonally across the tiles, cleaning excess grout off the surface while smoothing the joint line. Rinse the sponge often and go over twice for a clean finish.

Step 5

Cure and seal

Leave the grout to cure for 24 hours — no water or cleaning products on it during this time. Once fully dry, run your finger along the joints: they should feel solid and slightly concave. For shower areas, apply a grout sealer spray (Selleys or HG brand, ~$12 at Bunnings) to protect against mould and water ingress.

The stop point

If you find tiles that move, flex, or sound hollow when tapped — or if there is black mould visible deep behind the grout — stop immediately. This signals water damage behind the wall, and you need a licensed tiler or builder to investigate before it becomes a much bigger repair.

Mendy calls tradies for you. Your first booking is free, then $3.50 a booking.

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