Wall-mounting stock cupboards. First, find the wall studs. A cabinet that is wide enough should be secured to at least two of them.
Mark level lines across the wall for the cabinet’s top and bottom; mark the center of each stud on both lines. Rule perpendicular lines for the cabinet sides too.
Nail a temporary ledge on the bottom line and prop the cabinet on it to check whether the sides fit snugly against the wall. If the cabinet has a recessed back, you can correct any gaps by trimming the sides: set a compass to the size of the largest gap and
use it to trace the wall contour onto the side. If the back is flush, cover visible gaps with matching wood trim after the cabinet is up. Mark the stud centers on the cabinet’s top and bottom; then take the cabinet down and connect the lines on the back.
With a recessed-back cabinet, sand or plane the sides to the wall contour; Then place tapered cedar shingles, one atop the other, centered along each stud line, as shown. Adjust them to the proper thickness and tape them to the back.
Reposition the cabinet and drill pilot holes through the back and shingles into the studs 11/2 to 2 inches from the top and bottom. Secure the cabinet with screws long enough to extend at least 2 inches into the studs. If the cabinet is wood, countersink the screwheads; on a metal cabinet, use roundhead screws and washers.
To mount a narrow cabinet, nail two 1 x 4 furring strips across the studs and secure the cabinet to them. Notch the sides of a recessed-back cabinet around the strips. The method can also be used to mount a row of cabinets side by side.