What is the required space between abutting surfaces of plywood substrate?

The required space between abutting surfaces of plywood substrate is 1/4 inch. This spacing is essential because it allows for the natural expansion and contraction of wood materials due to changes in humidity and temperature. If there is no adequate gap, the plywood can warp, bow, or buckle under stress, leading to potential issues with the flooring or tile installation above. Additionally, the 1/4 inch gap helps to prevent edge-to-edge contact, which can create a weak point in the subfloor that may compromise the integrity of the installation over time. Understanding and applying this standard is crucial for ensuring a durable and long-lasting tile installation on a plywood substrate.