Installing cabinets is a moderately simple project that most well versed DIYers will undergo at some point. Most of the time it is a simple matter of discovering where the studs are and making sure you hit them with your installation hardware to provide adequate strength for long lasting cabinet installations. Some installation sites may not be up to code, which requires one stud every 16 inches. In these cases it is best to provide a way to spread the load over the available framing members. Installing cabinets without enough studs is challenging but doable.
Preparing the wall
Use a stud finder to locate the existing studs and mark them carefully. Mark each stud at the top and bottom of your wall cabinet installation area. If you have at least one stud behind each cabinet proceed with the following method. If there is less than 1 stud per cabinet consider moving your cabinets or tear down the drywall and add studs to the wall before installing your cabinets.
Cut ¾ inch plywood panels the height of your cabinets long enough to cover the entire installation area. Cut your panels long enough to span at least 3 studs for each piece. Mark the outline of each panel on the wall in its correct position. Mark lines on the plywood to line up with the center of each stud for screw placement.
Run a generous bead of liquid nails type construction adhesive, on the opposite side of the plywood from your screw lines, around the panel an inch or 2 from the edge. Apply lines of liquid nails inside this rectangle about every 6 or 8 inches across the panel.
Press the panel into place, sliding it slightly side to side to settle the adhesive. Line the panel up with its outline and add 3 inch screws into the studs about ever 10 inches. Repeat this process with each panel required. Add panels at the bottom of the wall for lowers. Install your cabinets as you normally would.
Installing the Cabinets
For lowers: Place the cabinet against the panel and check for level. Run 3 inch screws through the back of the cabinet into the plywood panel, hitting the stud whenever possible, making sure to run screw through the horizontal installation cleats in the back of the unit.
Add the next unit by leveling it, flushing it up with the first and screwing through the side panel into the first cabinet. Screw it to the wall as per first unit.
For uppers: follow similar procedure making sure cabinet is supported until fully fastened to the wall. Use at least 6 screws per unit. There are typically 2 horizontal cleats (plywood or whitewood ¾ inch boards located behind the back panel) 1 at the top and 1 at the bottom of each unit. Locate and run screws through these. Run as many of your screws as possible into studs for the most secure installation. Where screws are running into plywood panel substitute 1/58 inch screws for 3 inch.