The Seven Steps
Rooftop Mechanical Units

Purpose

To secure rooftop mechanical units.

Caution

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

Recommendation

Install clips and blocking.

Supplies Required

  • Clips, Z and L—1/8″ thick
  • Lag bolts—3/8″ diameter (for wood)
  • Sheet metal screws—No. 10 x 3/4″ (for steel)
  • 4x blocking (for wood)
  • Blocking—L2 x 2 x 3/8″ (for steel)
  • Drive pins
  • Framing clips (for wood) Simpson A35

Installation

Mechanical Units with Blocking and Clips on a Wood Roof
Source: Noson, Perbix, SSD

Mechanical Units with Blocking and Clips on a Steel Roof
Source: Noson, Perbix, SSD

To install blocking and clips for a wood roof, follow these steps:

  1. Insert 4x blocking between existing joists with framing clips.
  2. Attach Z or L clip to mechanical unit with corresponding fasteners and attach to blocking. Place clips at 24″ on center minimum.
  3. Patch roof as required.

To install blocking and clips for a steel roof, follow these steps:

  1. Insert blocking between existing joists and weld in place.
  2. Attach Z or L clip as mechanical unit with corresponding fasteners and attach to blocking. Position clips at 24″ on center minimum.
  3. Patch roof as required.