Installing a sink in a pre-existing granite countertop is not as complex as it may seem. Granite is a durable surface, especially if it is also sealed during the manufacturing process. Several issues need to be kept in mind when dealing with granite countertops, however. This heavy stone is more difficult to cut for the non-pro than composite materials, other man-made surfaces and even concrete. If the granite in your countertop is dark, avoid light-colored adhesives and sealants whenever possible. If they must be used, be vigilant that residues are wiped away as soon as possible to avoid staining the stone.

Instructions as follows:

Firstly, carefully measure the sink opening in your granite countertop. Once installed, the sink will typically take up about 33-by-22 inches from the outside rims. Write these dimensions on a notepad and take this information to your local home improvement center to select your new sink. Be sure to specify that you are interested in a top-mounted (or "self-rimmed") sink because your granite countertop is already installed and the opening has already been cut.

Secondly, purchase your sink and position it near the granite countertop. Apply polyurethane sealant to the "lip" beneath the edges of the sink. Keep in mind that unsealed stone absorbs stains easier and presents more of a challenge to clean. If this describes your counter, select sealants and caulking specially designed for this type of stone. It will be easier to apply the polyurethane if the sink is turned over and held tilted at an angle while you do this. If possible, ask another person to hold the sink on one side, lifting it on one end. The rest of it can remain on the floor while you apply the sealant. The two of you can flip the sink carefully back over and bring it up and over the countertop.