HVAC Units


To secure HVAC units mounted on vibration isolators.


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

Larger imageRestraint Bracket

Source: Noson, Perbix, SSD


Install restraint brackets or seismic snubbers.

Supplies Required

  • Angle—6" x 6" x 1/2" x 4"
  • OR
  • Bent plate—3/8"
  • Lag bolts—5/8" diameter x 6" (for wood)
  • Expansion bolts—5/8" diameter x 4" (for concrete)
  • Flex-line
  • Larger imageSeismic Snubber

    Source: Noson, Perbix, SSD

  • Steel Z snubbers (or other seismic type snubber)
  • 4 x blocking (for wood construction)
  • Framing clips (for wood construction)


Larger imageHVAC Unit

Source: Noson, Perbix, SSD

Restrain Bracket Installation

  1. Provide two angles or bent plates at each corner of the unit.
  2. Bolt to support with one bolt per angle. (For wood use two lag bolts at 3" spacing per angle.)

Seismic Snubber Installation

  1. Provide two snubbers at each corner of the unit.
  2. Bolt to support, providing sufficient free play to allow unit vibration under normal use.


Provide Flex-line at piping (see Piping).

©2017 SCEC Southern California Earthquake Center @ USC