What is the item used under the shower pan that creates the slope for the drain when installing a new shower?

The item used under the shower pan to create the slope for the drain is called a "shower pan liner" or "shower pan membrane". It is typically made of PVC or CPE (chlorinated polyethylene) and is installed over the subfloor and around the drain to create a waterproof barrier.

The liner is then sloped towards the drain using a combination of techniques, such as sand or mortar beds, pre-sloped foam panels, or adjustable slope systems. The choice of method depends on the specific requirements of the installation and the installer's preference.

Once the liner is in place and sloped properly, the shower pan can be installed on top of it, and the tile or other finish material can be applied. Proper installation of the shower pan liner is crucial for ensuring that water drains properly and does not seep into the subfloor or surrounding areas, causing damage or mold growth.

HydroBlok systems are known for their durability, water resistance, and ease of installation. They can be used for both residential and commercial applications and are suitable for a variety of finishes, including tile, stone, and vinyl.