Waterproof microcement surface. One layer is enough
On the market, you will commonly come across various solutions that offer a waterproof microcement material for swimming pools. Many of them are based on the application of multiple components. However, multiple layers applied in several steps, technological pauses and long hardening times significantly prolong the implementation and increase the risk of faulty installation.
However, there is now a range of special microcements for swimming pools, which are already waterproof in themselves. So you won't need to apply multiple layers of sealant with the necessary twenty-four-hour breaks to ensure that water doesn't leak anywhere.
As it is a fully waterproof coating, there is no need to install a vapour barrier when using a one-coat material. The sealer is only applied to provide the chemical resistance that is necessary against chlorine and salt. If you are installing a new surface over existing tiles, the surface needs to be primed with a primer to improve adhesion in both cases for a perfect result.