In this video, This Old House general contractor Tom Silva explains how to install a tub grab bar.
Steps for installing a tub grab bar
1 Mark mounting holes on tub wall using a level; choose a location 33 to 36 inches above floor.
2 Drill pilot holes through wall with 3/16-inch-diameter carbide-tipped masonry bit.
3 Bore holes for hollow-wall fasteners with 1 ¼-inch-diameter carbide-tipped hole saw.
4 Peel off protective paper from back of fasteners to expose adhesive.
5 Press hollow-wall fasteners into holes, then turn the center screw counterclockwise to release the wall-grabbing fingers.
6 Once fingers pop open, turn screws clockwise to tighten the fasteners.
7 Place grab bar in position over wall fasteners, then tighten the mounting screws.
8 Slide the escutcheons into place to conceal the mounting screws.