The Seven Steps
HVAC Units


To secure HVAC units mounted on vibration isolators.


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


Install restraint brackets or seismic snubbers.

Supplies Required

Restraint Bracket
Source: Noson, Perbix, SSD

  • Angle—6″ x 6″ x 1/2″ x 4″
    Bent plate—3/8″
  • Lag bolts—5/8″ diameter x 6″ (for wood)
  • Expansion bolts—5/8″ diameter x 4″ (for concrete)
  • Flex-line
  • Steel Z snubbers (or other seismic type snubber)
  • 4 x blocking (for wood construction)
  • Framing clips (for wood construction)


Source: Noson, Perbix, SSD

Seismic Snubber
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).