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GENERAL INSTALLATION METHOD


Grease & 2-hour Ventilation Air Duct Systems

Two-layers of CL4FIRE™ ductwrap constructed as follows:

  • First Layer installation allows snugly fitted butt seams throughout. (minimum 1/2" joint compression)
  • Second Layer installed with snugly fitted seams staggered joint between the first and second layers by a minimum of 6".
  • When encountering ductwork flanges it is not required to have the 1st layer of CL4FIRE™ ductwrap cover the top of the flange. It is only required that ductwork flange locations have the 1st layer of CL4FIRE Ductwrap insulation snugly butted against both sides of the flange.
  • 3" Overlaps can be substituted for butt-seams if desired
  • For 2 or 3-sided systems see CL4FIRE™ Ductwrap “2 or 3” sided Pinning Only Method or alternately “2 or 3” Sided Banding Method.

1-hour Ventilation Air Duct Systems
  • For one hour Ventilation Air Duct Systems, only one layer of CL4FIRE™ Ductwrap insulation is required using a 3" overlap at seaming locations.

Grease Duct System
  • Maximum 36" x 36" (1296 sq. inch) - Rectangular, Square, or Round #16 Gauge Grease Duct assembly installed per NFPA-96 guidelines in accordance with applicable building code requirements.

    Note: CL4 Inc. requests a review for ductwork larger than indicated to help ensure installation integrity.

Ventilation Air Duct System
  • Maximum Dimension 54" Rectangular, Square, or Max 1296 sq. inch Round #22 Gauge or Greater Air Duct Assembly rated for maximum 300 Pa negative pressure within the duct.
  • Complying with SMACNA or NFPA 90A requirements.

    Note: CL4 Inc. insists on reviewing ductwork installation details for ducts larger than indicated to help ensure product installation appropriateness & integrity

Support Rods & Cradles
  • Minimum 3/8" steel threaded rod & 1-1/2" x 1-1/2" x 3/16" steel angle cradles for ductwork up to 160 sq. inches in size
  • Minimum 1/2" steel threaded rod & 2" x 2" x 1/4" steel angle cradles for ductwork greater than 160 sq. inches in size
  • Support rods to be anchored to concrete using pass thru method with a nut & washer on the top of the concrete slab, or by using suitable carbon or stainless steel masonry anchors penetrating a minimum 2" depth into the concrete slab
  • Maximum distance of 60" allowed between non-insulated duct supports

    Note: If desired, it is acceptable to encase the cradle support assembly along with the duct within the CL4Fire Ductwrap insulation (i.e.: cocoon wrap) during the installation. A slit is allowed in the duct wrap in order to position around the threaded rod. Slit must be repaired and sealed using a minimum depth of 1/4" with a bead also placed around the circumference of the support rod. Seams can be sealed using any combination of the approved installation methods.

Banding (not required with “Pinning Only” method):
  • 1/2" stainless steel banding for grease duct and 2-hour ventilation air duct systems installed as outlined in CL4Fire Ductwrap installation Methods
  • 1/2" wide carbon steel banding for Grease Ducts and ventilation air duct systems requiring only a 1-hour ‘external’ fire rating

    Note: Grease ductwork always requires 2-layers of CL4FIRE Ductwrap Insulation.

Firestop:
  • Minimum 4" depth of 4 pcf (or heavier) mineral wool insulation or CL4Fire Ductwrap fiber firmly packed into 1 or 2-hour rated concrete
  • Full depth of mineral wool or CL4FIRE fiber (less caulking depth) into framed gypsum wall or framed wood floor/gypsum ceiling
  • Assemblies are to be topped with Hilti FS One Sealant to a min. depth of 1/4" on top of floor or both sides of wall assembly
  • Maximum annular space of 4" between duct and floor or wall substrate is allowed
  • See Intertek Testing Services (ITS) listing CL4/PHV 120-01 for additional firestop details

Gypsum Shaft Transition (if required):
  • Should a transition be required from a gypsum shaft system to a CL4FIRE Ductwrap installation the annular space around the duct and the shaft must be filled with a minimum of 4" depth of CL4FIRE insulation and topped with a 1/4" depth of HILTI FS ONE SEALANT flush with the surface of the gypsum
  • No aluminum tape is required on seams, but it may be used for cosmetic reasons if desired

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INSTALLATION
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