Drilling Into Tile for a Shower Door Without Damaging Waterproofing

Plan every fixing as a hole through the waterproofing layer. That means choosing a position that lands on solid material, away from the wettest part of the wall and off the joints, drilling without cracking the tile, and sealing the fixing once the door has been adjusted rather than before.

The reason is that a fixing is the only part of the installation that deliberately opens the layer water is kept out by. Handled in the right order, the opening is small, it lands on something solid, and it is closed again. Handled in the wrong order, it becomes a slow path into the wall that shows up months later as a damp patch on the other side.

Waterproofing Risk Points

Waterproofing fails at edges and penetrations rather than across the middle of a wall, and each fixing is a penetration. Four places on a shower wall carry more risk than the rest.

• The fixing itself. A fixing that passes through tile and board reaches whatever is behind it; if that is a cavity rather than structure, the hole is an opening as much as an anchor.
• The base of the wall. The lowest part of a shower wall sees the most water, which makes fixings close to the base the ones most likely to be wet.
• The joint line. Fixing on or beside a grout line or a silicone joint risks cracking the joint rather than drilling cleanly.
• The corner. Corners concentrate both water and movement, so a fixing there has less margin than one in the middle of a panel.

Decision rule: if a fixing cannot be placed away from the base, off a joint and onto solid material, move the door's fixing position rather than the fixing method. Moving a hinge plate along the opening is cheaper than repairing a wall.

Drilling Tile Safely

Drilling into a tiled wall is a five-step job, and the steps exist because each one prevents a specific failure.

1. Confirm what the fixing will land on before drilling anything - structure, solid wall or cavity. This decides whether the fixing can be used at all.
2. Mark the position with tape rather than a pencil, so the bit does not skate across the glaze when it starts.
3. Start in the tile only. The surface of a tile is drilled differently from what lies behind it, and the two stages are done separately rather than in one pass.
4. Keep the drill slow and steady with light pressure. Heat is what cracks tile, and speed with pressure is what makes heat.
5. Support the tile where it is bonded to board, so vibration does not lift it away from its bed.

Drilling through a joint or directly beside one is the most common way a tile cracks, so the position is chosen in the middle of a tile wherever the door's fixing centres allow it. Where they do not, the fixing position moves rather than the tile being drilled at its weakest point.

Sealing the Fixing After Drilling

A fixing that is not sealed is a hole with a screw in it. The sequence matters more than the product: fix first, adjust the door, then seal around the fixing, then re-check the seal once the door has settled into use.

• Seal where the fixing meets the wall, not over the head of the screw, because the water path is at the edge of the hole rather than at the top of the fastener.
• Do not seal a fixing that still has to be adjusted, because the adjustment will move it and open the seal it was given.
• Re-check the seal after the door has been in use, since adjustment and settlement both move a fixing slightly and both can open a joint that looked complete.

The order also protects the door: a fixing sealed before the door is set leaves no room to correct the geometry, and correcting it afterwards means cutting the sealant out and starting again.

Practices to Avoid

Five habits cause most of the damage that follows a fixing, and each one is avoidable without extra work.

• Drilling to a fixed depth without knowing what is behind the tile, which turns a fixing into a hole into a cavity.
• Sealing over a fixing that is still being adjusted, which hides movement rather than stopping water.
• Using a hammer drill on wall tile to save time, which is the fastest way to crack a tile that was otherwise sound.
• Fixing into the base of the wall, where the waterproofing detail is most vulnerable and the water is most persistent.
• Treating a bead of sealant around the outside of a fixing as sufficient on its own, without the fixing landing on something solid.

Where the enclosure makes drilling avoidable altogether, that option is worth taking: the guide to installing without drilling tile covers the arrangements that use existing surfaces instead, and the wall types guide covers what each substrate will accept.

Before drilling, confirm: the material behind each fixing; a position that avoids the base, the joints and the corners; a marking method that will not let the bit skate; a slow start through the glaze; and sealing that happens after the door is adjusted rather than before. Where a fixing lands somewhere uncertain, requirements can vary by jurisdiction - verify applicable local requirements and the product installation instructions before proceeding. The tile installation planning guide covers how the fixing positions are decided in the first place, and the shower doors collection shows the fixings each door is supplied with.