What is the recommended spacing for subfloor plywood underlayment?

The recommended spacing for subfloor plywood underlayment is 1/8" on both ends and sides. This spacing is essential for allowing the plywood to expand and contract with changes in temperature and humidity, which helps to prevent buckling and cracking of the subfloor. Such spacing ensures that the panels have adequate room to move without causing damage.

Maintaining this specified gap minimizes stress on the joints and allows for air circulation, which can help with moisture management. In practice, if the spacing is too tight, it can lead to a range of issues, including improper installation performance where the plywood may not lay flat, potentially causing uneven floor surfaces once finished flooring is installed. Thus, adhering to the 1/8" spacing is critical for achieving a stable and durable subfloor system.