Walls only look solid from the outside. Drywall, also known as sheetrock, is only 1/2-inch thick and is brittle. Walls made of lath and plaster can be thinner than drywall and equally as brittle. Attaching shelving to these walls should be done with care and planning. This is done both to prevent damage to the wall, as well as possible injury or property damage when the shelving unit eventually pulls free and drops to the floor.
Use a stud finder to locate the structural 2-inch by 4-inch boards in the wall. If you're mounting a shelf that's expected to hold more than 4.54 Kilogram, the mounting brackets must be secured to the studs that support the walls.
Drill a hole with a masonry bit for each hole in the shelf's mounting bracket. Each hole must be slightly smaller than the diameter of the screw that will be used to secure the mounting bracket to the wall.
Secure the shelf's mounting brackets to the wall with screws driven securely into the studs.
Secure the shelf to the mounting brackets.
Small ornamental shelves can be attached to lath and plaster walls with toggle bolts. Drill a pilot hole with a masonry bit slightly larger than the toggle, insert the screw through the mounting hole on the shelf bracket, thread the toggle onto the end of the screw and push it through the hole in the wall. Tighten the screw to hold the toggle in place on the backside of the wall. This should only be used to hold weights up to 2.27 Kilogram. Wood lath becomes increasingly brittle as it ages and should not be considered as a reliable anchor point for shelving or other wall hangings.