While heavy countertops make for durable surfaces, they require extra support. Adding plywood beneath stone slabs provides the reinforcement necessary to prevent cracks and damage.
A lack of support and poor maintenance can lead to cracks, which shorten your counter’s lifespan, necessitate professional repairs, and sometimes require a full replacement.
Thinner countertops are most susceptible to damage, but they all can benefit from added support. If your counter has an overhang over 6 inches, it’ll also need extra reinforcement.
Plywood underlayments come in a variety of strengths and pressure resistance levels. Choose a water-resistant one, as most countertops come in contact with water regularly.