How to Finish Installing Base Cabinets
After you have hung your wall cabinets and installed the corner base cabinet, you can finish your cabinet installation. Finishing the base cabinet runs is less strenuous than hanging the wall cabinets because the cabinets rest on the floor and don't need to be supported while you secure them to the wall. However, it's still a good idea to have someone nearby to help make adjustments.
Before you install your sink-base cabinet, you may need to make cutouts for the plumbing pipes if the cabinet has a back. Measure from the side of the adjacent cabinet to the center of each plumbing supply or pipe (drain line and water supply lines). Transfer those measurements to the back of the cabinet and use a hole saw or jigsaw to cut out openings for your plumbing pipes to fit through. Make sure that the measurements are accurate — you'll make an expensive mistake if you have to replace the sink base cabinet. Remember the old rule: "Measure twice, cut once." If you do happen to screw up big-time, you can cut a piece of 1/8-inch-thick Masonite plywood/paneling, adhere it to the messed-up panel and cut new holes. No one will know that you goofed!
Follow these steps to finish the base cabinet run:
Place the second cabinet in position and check it for plumb and level.
If shims are needed, gently tap them into place with a hammer.
Don't trust your eye to check for level. Just because the two cabinets are flush along the top edge doesn't mean that they're both level and plumb. Check it and adjust as necessary. You may need to place shims under the front or exposed side of the cabinet and between the back of the cabinet and the wall.
Join the two cabinets with two clamps, located about 1/4 of the distance from the top and bottom.
Use wooden screw or short bar clamps with padded jaws that won't mar the cabinets. As you tighten the clamp, ensure that the face, top, and bottom of the two frames are all perfectly flush.
Install the remaining cabinets and any required filler strips the same way, attaching each one to the previously installed cabinet.
Complete the installation of each cabinet and then check all installed cabinets for level, plumb, and alignment before moving on to the next cabinet.
If your new cabinets include a separate pantry unit, install it the same way you installed the first cabinet of either the wall or base run: Make sure that it's level and plumb and that it aligns properly with horizontal and plumb reference lines before you secure it to the wall with 3-inch drywall screws.
After the cabinets are secured, score and break off all protruding portions of shims. You may find that you have a gap along an end panel and the wall or along the floor where shims may have been needed. Use a decorative trim molding to cover it. To cover the gap at the floor along the area called the toe-kick, install a strip of matching hardwood or vinyl base molding, which can be cut with a utility knife and is adhered with special mastic.
Don't reinstall the doors and drawers on the base cabinets until after you've installed the countertop. They are safer out of the way, and you need to have access to the underside of the countertop to secure it to the cabinets.