VEVOR Shower Niche Ready for Tile 16" x 16", Single Shelf Organizer, Square Corners Wall-inserted Niche Recessed, Sealed Protection Modern Soap Storage Niche for Shower Bathroom, Black

Based on the product information, it does not require maintenance. The shower niche is made of XPS extruded foam board which is durable and resistant to decomposition and decay.

According to the product information, it is easy to install horizontally. The installation kit provided allows for simple horizontal or vertical installation by following the steps.

The product description states that it is sealed and completely waterproof, employing a triple waterproof base of XPS extruded foam board, cement mortar, and waterproof coating. However, it does not specifically mention its effectiveness in humid areas.

No, it does not self-drain.