How to Rough a Double Sink

Have an assistant hold two 1/2-by-24-by-48-inch boards on their long, skinny edges about three feet apart. Hold these boards parallel and consider them the top and bottom boards. Slide a 1/2-by-24-by-36-inch board against one set of the top and bottom board ends, perpendicular to them. Consider this board a side board. Drill holes every six inches through the side board and into the top and bottom boards. Secure them in place with 2-inch wood screws drilled into each hole. Repeat for an additional side board on the opposite end.

Set a 1/2-by-36-by-49-inch board on top of the rectangular frame and adjust it so its outside edges are even all the way around the frame. Drill holes through this board, which is the rear board, every 12 inches into the top, bottom and side boards. Set a 2-inch wood screw in each hole and tighten them securely.

Flip the vanity over so the open section is facing up. Position a 1/2-by-24-by-35-inch board directly in the center of the opening, parallel to the side boards. Drill holes every six inches through the top and bottom boards and into the ends of this board, which is the middle board. Attach the middle board in place with 2-inch wood screws. Rotate the vanity so it's in its intended orientation and repeat the middle board attachment process with the rear board.

Rotate the unit so the rear board is once again flush with the working surface. Position two 1/2-by-24-1/2-by-36-inch boards, which will be the doors on the opening, so they are evenly lined up with the edges of the vanity frame. Position two side-mount cabinet hinges against each door and side board joint, and mark the screw holes, lifting the doors slightly if necessary. Drill out these holes and attach the hinges with 1/2-inch wood screws.

Position the unit against the wall where it will be installed and mark the locations of the wall plumbing. Cut out the necessary sections with a saw. Reposition the vanity unit and determine the locations of the sink installations. Cut out the necessary areas and position the sinks within the cutouts.