How to stop water leaking through tiles?

Jess1988

Hi I have a deck off the front of my upstairs house which has been tiled when it rains there is water leaking through it which holds my garage underneath causing a water buildup just wondering if there is something I can do to seal the grout I don't have the money to be having the tiles ripped up and reseal and then retile

MitchellMc

Hi @Jess1988,

The issue you’re describing is unfortunately quite common with tiled decks and balconies, and it’s important to understand what might be happening. Tiled outdoor areas should have a waterproofing membrane installed underneath the tiles to prevent water from seeping through to the structure below. If you’re seeing a significant amount of water leaking into the garage, it suggests that either the membrane was never properly installed or it has been compromised over time.

While sealing the grout might seem like an easy fix, grout itself isn’t waterproof—it’s porous by nature. If water is leaking in large volumes, it’s likely finding its way through cracks in the grout, around tile edges, or even through hairline cracks in the tiles themselves. It’s worth starting by thoroughly inspecting the tiled area, especially around the perimeter, for any gaps or deteriorated sealant. Resealing these edges and applying a quality penetrating tile and grout sealer can help reduce water ingress, but it won’t solve the underlying problem if the membrane has failed.

The main concern is that ongoing water penetration can lead to structural issues over time, such as rotting joists, rusting reinforcement, or damage to the ceiling of the garage. While you’ve said you don’t have the budget to have the tiles removed and the area re-waterproofed, it’s still worth getting a professional to assess the extent of the problem so you understand the risks. In the meantime, addressing obvious cracks and maintaining good drainage away from the deck will at least help minimise further damage.

Please let me know if you have any questions.

Mitchell