How Do I Drill Through Tiles Without Cracking Them?

Drilling through tiles is one of those jobs that looks straightforward but can go wrong quickly if you rush it. A cracked tile is frustrating and expensive to replace — especially if the tile is discontinued or part of a wet area. With the right tools and a bit of patience, most homeowners can drill a clean hole through ceramic or porcelain tiles without drama.

Choose the Right Drill Bit

This is the single most important factor. Using a standard twist bit or masonry bit on tiles will almost certainly cause cracking or chipping.

• Diamond-tipped core bits – The gold standard for porcelain and natural stone. They cut cleanly and last well. Available at Mitre 10 and Bunnings.
• Carbide-tipped spear-point bits – Suitable for softer ceramic tiles. More affordable, but wear out faster on hard porcelain.
• Avoid: Standard masonry bits, HSS twist bits, or percussion/hammer drill settings — these will crack tiles.

Matching the Bit to Your Tile Type

If you're unsure what type of tile you have, porcelain is generally denser and heavier than ceramic, and will chip more aggressively if drilled incorrectly.

Mark Your Spot Carefully

Before you drill, take time to mark the exact position of your hole. Use a felt-tip pen or a small piece of masking tape — tape has the added benefit of giving the bit something to grip so it doesn't skate across the glazed surface when you start.

Important: Before drilling into any tiled wall, use a stud finder and a cable/pipe detector to check for hidden electrical wiring, water pipes, or structural framing behind the tile. In NZ bathrooms and kitchens especially, pipes are often closer to the surface than you'd expect. WorkSafe NZ has guidance on working safely around hidden services.

Set Up Your Drill Correctly

• Turn off hammer/percussion mode – This is critical. Hammer action will shatter tiles. Drill in rotation-only mode.
• Use a slow to medium speed – High speed generates heat and vibration, both of which cause cracking. Start slow and maintain a steady pace.
• Apply light, consistent pressure – Let the bit do the work. Forcing it will crack the tile or burn out the bit.
• Keep the bit cool – For diamond bits especially, use water to cool the cutting area. You can make a simple dam with plumber's putty or blu-tack around the hole and fill it with a little water, or have a helper drip water onto the bit as you drill.

Step-by-Step Drilling Technique

1. Apply masking tape over the drill spot to prevent the bit from slipping.
2. Mark your centre point clearly on the tape.
3. Start at a slight angle (about 45°) to create a small notch, then gradually bring the drill upright — this helps prevent skating on glazed surfaces.
4. Drill slowly with light pressure, keeping the bit cool with water if using a diamond bit.
5. Ease off pressure as you near the back of the tile to avoid blowout on the reverse side.
6. Switch to a masonry bit once you're through the tile and into the substrate (concrete, block, or plasterboard) behind it.

Drilling Near Tile Edges and Grout Lines

Avoid drilling too close to the edge of a tile — the tile is most vulnerable here and prone to cracking. As a general guide, try to stay at least 15–20 mm from any edge. Drilling through grout lines is sometimes easier on the bit but can weaken the grout joint, so it's best avoided where possible.

Wet Area Considerations

If you're drilling into a tiled shower, bathroom, or kitchen splashback, be aware that NZ Building Code clause E3 (Internal Moisture) requires wet area linings to remain waterproof. Any penetration through tiles in a wet area must be properly sealed. Use a suitable silicone sealant — products from Sika or similar are widely available — around any fixings or pipe penetrations to maintain the waterproof membrane integrity. Failing to seal penetrations can lead to moisture getting behind the tiles, causing damage over time.

For advice on wet area construction standards, BRANZ is an excellent NZ resource.

When to Call a Professional

Some situations are best left to a qualified tradesperson:

• If you need to drill for plumbing or drainage – Installing or modifying water supply pipes or drains is restricted work under the Plumbers, Gasfitters and Drainlayers Act. Only a licensed tradesperson registered with the Plumbers Gasfitters & Drainlayers Board can legally carry out this work.
• If you need to drill for electrical work – Running cables, installing outlets, or connecting fittings in walls is restricted electrical work under NZ law. Only a registered electrician (check the Electrical Workers Registration Board) can do this legally and safely.
• If you're unsure what's behind the wall – A professional tiler or builder can assess the situation before any drilling begins.
• If you need to replace a cracked tile – A qualified tiler will match grout, maintain waterproofing, and ensure the repair meets the NZ Building Code.

You can find qualified local tilers and tradespeople on tradedirectory.co.nz.

Sources & Further Reading

• WorkSafe NZ – Working safely around hidden services
• BRANZ – Wet area and moisture guidance
• MBIE Building Performance – NZ Building Code
• Plumbers Gasfitters & Drainlayers Board – Licensed tradespeople
• Electrical Workers Registration Board – Find a registered electrician
• Mitre 10 – Diamond drill bits and tiling tools