When installing granite countertops, it is essential to provide proper support to the heavy stone. Plywood is commonly used as an underlayment for granite countertops. However, not all types of plywood are suitable for this purpose. The most appropriate type of plywood to use under granite countertops is "Exterior Grade Plywood" or "Marine Grade Plywood." Here's why:
Strength and Durability: Exterior grade plywood is designed to withstand exposure to moisture, humidity, and temperature fluctuations, making it a sturdy and reliable choice for supporting heavy granite slabs.
Moisture Resistance: Exterior grade plywood is manufactured using water-resistant glues, which helps protect the plywood from absorbing moisture, preventing warping or delamination.
Avoiding Expansion and Contraction: Plywood under granite countertops may be subjected to slight movements due to changes in temperature and humidity. Exterior grade plywood has a better ability to handle these changes without warping or buckling.
Smooth Surface: Exterior grade plywood typically has a smoother surface compared to other plywood types, which is essential for proper adhesion and support of the granite slab.
Resistance to Decay and Rot: Marine grade plywood, a type of exterior grade plywood, is specifically designed to resist decay and rotting caused by exposure to moisture.
When using plywood as the underlayment for granite countertops, it's crucial to ensure the plywood is securely attached to the cabinet framework or supporting structure. It should also be perfectly level and flat to provide a stable base for the heavy stone. Additionally, appropriate adhesive or thin-set mortar is used to bond the granite to the plywood securely.
Before proceeding with the installation, it's always best to consult with a professional or follow the recommendations of the granite supplier to ensure the proper type and thickness of plywood are used for your specific installation. This will help ensure a successful and long-lasting granite countertop installation.