Granite is a very heavy, dense stone that requires support when used in countertops and other similar designs. Typically, this support includes a plywood base and an underlayment of cement board. Using proper materials and techniques ensures a reliable, long-lasting countertop.
Granite countertops can come in different thicknesses, but the preferred thickness is three centimeters, or almost 1 1/4 inch. For this thickness, one square foot of granite will weigh between 18 and 20 pounds. Unless you have very little counter space, this adds up quickly, creating a very heavy countertop. Likely, the cabinets and shelving that will support the granite countertop are sturdy, but their simple framework won’t hold up over time. Underlayment will give the framework greater sheer strength, and will take on any stresses to the frame over time. If the frame were to ever buckle, the granite would crack along with it. There’s no point taking the chance and having it all come crashing down.
A vital part of this support is the underlayment. This flat surface provides continuous weight distribution, which adds strength to the extra support beams to help prevent cracking of the granite countertop. The standard thickness for cement board underlayment is half an inch, which provides structure and solid counter thickness. The underlayment must be attached to the plywood base, and the screws used to hold it all in place cannot protrude, otherwise the granite slabs or tiles will not lay flat. The underlayment also helps to absorb the pressure of use, supporting the heavy granite countertop, as well as all the activity it has to take.
It is also good to note that underlayment is waterproof. Granite countertops are moisture- and bacteria-resistant, but granite is by nature porous, so most countertops are sealed to help protect the stone from stains and other damage. If any moisture does manage to reach the underlay, you don’t have to worry about damage or mold to the supporting structures.
Underlayment of granite countertops is essential. Granite is a very heavy material, and can be expensive, so it is important to protect it, along with the kitchen as a whole. As a natural rock, granite is long-lasting, but it can crack and be damaged if not properly supported. The professionals at Granite Unlimited install this support and underlayment prior to installing all granite countertops, ensuring your countertops are secure and ready to take on the pressure and wear of regular kitchen use.