Sealing masonry surfaces
The best protection against efflorescence and water damage is to use a penetrating sealer to make the surface entirely waterproof. The products we recommend using are a masonry sealer such as Resistain or Shower Plug. Both will waterproof any masonry substrate, but Resistain is a stain-proof sealer that has the added feature of stain-resistance.
Penetrating waterproof sealants are liquid solutions that repel water from masonry. Resistain and Shower Plug are brush-on waterproof sealants that can be applied using a brush, roller or spray. When applied to a clean, dry masonry surface, the penetrating sealer will soak in, bind there and create an electro-chemical barrier that repels water for decades.
Once applied, the surface will become impermeable to water, and if treated with Resistain, will also be protected against all forms of stains. Any water already in or beneath the surface will dry out.

The extent of the water damage problem along the tiled area. Applying a penetrating sealer to this surface when it was originally laid would have protected the entire surface for decades, avoiding damage and repairs later on. An unsealed surface is guaranteed to experience water damage over time.
For an easy way to learn how to apply a masonry sealer like Shower Plug, our handy guide can help you through the process and this will seal your surface for 10 years.