Which of the following materials is NOT typically used as a tile underlayment?

The material that is not typically used as a tile underlayment is luxurious carpet. Tile underlayment serves as a foundational layer that provides support, moisture resistance, and stability to the tile installation. The primary purpose of underlayment is to create a smooth, even surface that helps prevent cracking and allows the tiles to adhere properly.

Cement backer board, plywood, and waterproof membranes are all commonly used as underlayment materials for tile installations. Cement backer board is specifically designed for tile applications and provides excellent moisture resistance and stability. Plywood can also be used in certain installations but must be properly prepared and installed to avoid issues. Waterproof membranes are essential in areas exposed to moisture, providing an additional layer of protection against potential water damage.

In contrast, luxurious carpet does not possess the structural properties needed for tile installations. It is a soft flooring material that is unsuitable as an underlayment because it lacks the necessary strength and stability to support tiles, which could lead to improper installation and damage to the tiled surface.