Shelf Units


To secure shelf units that may cause injury or damage from falling over and will dump contents onto the floor.


Install clip angles and steel struts for shelf units weighing less than 250 pounds.

Larger imageBookcases - floor anchorage options (6' or more in height)

Source: Governor's Office of Emergency Services

Supplies Required

  • Clip angles—1-1/2" x 1-1/2" x 1/8" (4' maximum spacing)
  • Lag bolts—3/8" diameter (for wood shelving)
  • Expansion bolts—3/8" diameter (for concrete floors and walls)
  • Steel strut—1-1/2" x 1-1/2" x 1/8"
  • Sheet metal screws—No. 10 x 3/4"
  • Machine bolts—1/4" diameter
  • Wood screws—No. 10 x 3/4"
  • Steel plates—1/8" x 3" x 6"
  • Strap bracing—16 gage x 1"

  • Installation

    Larger imageConcrete or Masonry Floor (left) Wood Floor (right)

    Source: Noson, Perbix, SSD

    Clip Angle - Wall Attachment

    1. 1. Attach the shelf unit directly to the wall with a clip angle.
    2. 2. Secure the unit to the wall with a lag bolt for wood. Embed it into a stud at least 2". (Do not attach to gypsum wallboard only.) OR Secure to wall with an expansion bolt for concrete.

    Clip Angle - Floor Attachment

    Attach a clip angle to a concrete floor with expansion bolts. OR Attach a clip angle to a wood floor with lag bolts.

    Larger imageMetal Shelving (left); Wood Shelving (right)

    Source: Noson, Perbix, SSD


    When anchoring to post-tensioned slab, locate and avoid reinforcing.

    Overhead Steel Strut Installation

    Secure overhead strut with screws to shelving.

    Larger imageConcrete or Masonry Floor (left); Wood Floor (right)

    Source: Noson, Perbix, SSD


    • For shelf units that weigh over 250 pounds (including contents), consult a structural engineer.
    • Attach shelving to frames.
    • Connect adjacent shelf units with steel plates and machine bolts.
    • Install strap bracing across back of shelving. Provide three screws at each end of the bracing.
    ©2017 SCEC Southern California Earthquake Center @ USC