A farmhouse kitchen sink, or apron sink, is a large basin sink which is typically deep, making it ideal for washing large pots and pans. It is often a single basin sink. The sink requires a deep U-shape cutout to seat the front of the sink. Most kitchen cabinets are too high to provide this, which means cabinets either need to be custom made to accommodate the farmhouse sink, or alterations must be made on the existing cabinets. Another consideration when installing the farmhouse sink is the sink's weight, which requires additional support.
Make a template for the front of the cabinet face. There may be a template supplied with the sink. If there is not, you can make your own template by laying the farmhouse sink, face down, on a piece of cardboard. Trace the outline of the sink onto the cardboard. If your farmhouse sink has a lip, note its location on the template, so you can make the proper adjustment when cutting the cabinet front. Cut the cardboard template out, and hold it against the front of the sink. If it is not exactly accurate, make adjustments to correct.
Place the cardboard template against the face of the kitchen cabinet, where the sink will be set. Trace the outline of the template onto the cabinet.
Cut the cabinet, using a saber saw, along the traced line.
Add support to your cabinet to hold the sink's extra weight. Additional supports and instructions may come with your sink. If not, add two ledgers inside the cabinet, for the sink to rest on. Position the ledgers so that each will be on opposite sides of the sink when the farmhouse sink is set in the cabinet.
Set the farmhouse sink in the cabinet. Adjust the sink so that it is level and fits in the cabinet properly. If necessary, use a rasp to remove wood or shim to prop the sink.
Seal the sink with silicone caulk.
Install the drain and faucets and connect the water supply.