Deflection Drift Angle (DDA)

CEMCO' s patented DDA (Deflection Drift Angle) is a UL certified composite intumescent/steel angle accessory that provides unencumbered fire-protection up to 2” at the head-of-wall joint in accordance with UL-2079 “Test for Fire Resistance of Building Joint Systems”. (US Patent #8,595,999)


  • The DDA provides a universal fit for any wall type regardless of the width, gauge, height, radius, pitch and whether it is a shaft wall or standard wall
  • Allows the contractor to install standard slotted or deep leg track because the DDA is installed only on the fire-rated walls
  • The DDA is easy to install.  It is tapped into place over the leg of the track.  No mechanical fasteners required
  • Fluted pan deck application only requires a single-sided spray application utilizing  any of Rectorseal brand fire sprays (Flamesafe, Bio Fireshield, or Metacaulk)  on standard or shaft wall assemblies
  • Fire spray goes over DDA before drywall installation for early unrestricted access to head-of-wall
  • Uses up to 75% less fire spray than traditional head-of-wall joint systems
  • 20 separate UL reports and over 100 different assemblies
  • The outer leg of the DDA is manufactured from red galvanized steel for easy recognition
  • DDA comes in 10’ lengths and 10 per box

Installation: Click HERE to see a short video...

  • Once framing studs are secured into place the DDA is lightly tapped into place over the leg of the header track
  • The DDA must be installed before drywall is installed
  • The ¾” leg is friction fit between the overhead structure and the web of the header track
  • No mechanical fastening is required. This will allow the wall assembly to move both laterally and vertically without any movement restriction from the fire-stopping material
  • End joints can be abutted tight or overlapped