Installing base cabinets is a process that follows the basic rules of carpentry - the final results should be straight, square, and strong. In new construction, subfloors are usually in good condition and provide a sturdy, flat surface for base cabinets to rest on. The same goes for newly erected walls - today's engineered lumber products combined with good construction practices typically mean walls will be plumb and true. In older homes, floors are more likely to have high and low spots, and walls, floors, and corners may not meet at perfect 90-degree angles. Your cabinet installer will remedy minor problems with a few common tools and a little ingenuity.
No two jobs are ever alike, but installing base cabinets is relatively straightforward. The first step is to identify the highest area on the floor and mark it on the wall. One technique is to use shims (tapered lengths of wood, usually pine) and a carpenter's level. The rear of the base cabinet must be level with the front. If the highest point on the floor is closer to the wall, the front of the cabinet must be raised with shims. If the highest point on the floor is farther away from the wall, the rear of the cabinet must be raised to the equal height.
Drawing a straight line on the wall to mark the top of the base cabinets will ensure that all of the base cabinets are installed at the identical height and the countertop will have a flat mounting surface. A 2×4 and a level are commonly used to make sure the line is perfectly straight. The standard cabinet height in the U.S. is 34-1/2-inches. Note: The height of the top line should be measured from the highest point on the floor.
With base cabinets, many installers secure all the cabinets to each other before attaching them to the wall. Standard bar clamps can be used to make sure each cabinet is secure before installing fasteners, but professional installers often use a tool called the “cabinet claw.” Its jaws pull the face frames of two cabinets together, and a front clamp aligns them flush with each other.
Before securing the cabinets to the wall, the installer will check to make sure that the cabinets are perfectly aligned with the line scribed on the wall, and that they are perfectly vertical from top to bottom, and level across the top. Using two levels simplifies the process. Shims are used to raise areas of the base cabinets off the floor or away from a wall into a level position. Whenever using a shim to adjust the cabinet where it meets a wall, it is always placed over a stud.
Once the cabinets are level, they can be secured to the wall. Fasteners should always be driven through the cabinet and into wall studs. Wherever shims are used, a fastener must be driven straight through them so they do not slip out of place and cause the cabinets to shift.
The final step is to install the doors, drawers, and hardware. Depending on the style of cabinet, the hinges may be hidden (installed on the inside of the frame) or visible. Some cabinets come with supplied hinges and are pre-drilled. To secure hinges on cabinets that are not pre-drilled, many installers make a template to ensure that all of the hinges line up across the face frames of the cabinets.