A:

Tanking is the act of installing a waterproof barrier into your installation in order to waterproof it.

Tanking is installed under the tiles and is required when installing showers and wetrooms.

It’s a common misconception that tiles and grout are waterproof! This isn’t helped by the grout manufacturers putting words like ‘water-resistant’ and ‘waterproof’ on the side of their products without explanation.

The fact that a grout may be waterproof means that the actual grout will not be broken down by water, but it doesn’t mean that grout won’t let water pass through it to the sub-straight below!

The next time you see grout get wet you might notice that it’s a slightly different colour, this is because the water is getting into the grout. Under a microscope you can see that grout is full of tiny holes. Given time, or pressure, as with a power shower, water can and does pass through the grout into the base surface below.

To ensure a shower or wet room location stays waterproof we need to make sure that wall behind the tiles is waterproofed. This is known as tanking.

The actual tanking process involves covering the entire surface to be made waterproof either with special waterproof sheets or a special waterproof coating. The corners will be correctly taped and the way the taping and coating is installed needs to be done in such a way that any moisture that gets through will enter the shower base and not drip behind it into the sub-structure of the room. Furthermore the tiles have to be adhered to this waterproof coating using the correct trowel and with the correct adhesive to ensure the correct amount of coverage behind the tile.

When done correctly we no longer need to rely on the tiles and grout holding back the water from your walls as the tanking behind does that job.

If your project requires tanking I will survey the area plus length of corners to be sealed and select and install the required tanking.

Additionally the grout in your shower enclosure or wet room can be sealed using special grout sealants, this will prevent your grout from absorbing water and soap and preserve that new look.

Note that totally waterproof grouts are available, these are two part epoxy grouts and only used in extreme conditions (such as food preparation areas), they are totally resistant to water and can’t even be stained by red wine, but are very expensive compared to the normal grouts.