Laying tile directly over a plywood subfloor is generally not recommended and can lead to various issues in the long run. Plywood subfloors have some flexibility and can expand and contract with changes in temperature and humidity. Tiles, on the other hand, are rigid and can crack if they are not properly supported.
Here are some potential problems that can arise from laying tile directly over a plywood subfloor:
Cracked tiles: The lack of a stable and rigid surface can cause tiles to crack or become loose over time, especially in high-traffic areas or where heavy objects are placed.
Uneven surface: Plywood subfloors may have small imperfections or irregularities that can transfer to the tile surface, resulting in an uneven and unattractive floor.
Subfloor movement: Plywood can flex and shift slightly due to foot traffic or structural movement, which can cause grout lines to crack and tiles to become loose.
Moisture damage: Plywood is susceptible to damage from moisture, and in areas prone to water exposure (e.g., bathrooms, kitchens), water can seep through the grout lines and cause the plywood to rot.
Insufficient support: Tiles require a solid and stable surface for proper support. Without a suitable underlayment, tiles may not adhere properly, leading to problems like tile lifting or "hollow-sounding" tiles.
To avoid these issues, it's recommended to use a tile underlayment or cement backer board over the plywood subfloor before installing the tiles. The underlayment provides a stable and water-resistant surface, ensuring the tiles remain firmly in place and minimizing the risk of damage over time. It also helps to level out the subfloor and create a smoother surface for tile installation.
If you're planning to install tiles, it's best to follow industry-standard practices and manufacturer recommendations to ensure a durable and long-lasting tile floor. Professional tile installers can offer expert advice and ensure the job is done correctly.