Constructions Standards Checklists

FLEX DUCT

HVAC SYSTEMS  A. Ducts and distribution boxes are installed per the layout drawing are stretched tightly and supported above the bottom cord to allow for full depth of insulation.  B. Held a minimum of 6" away from roof deck sheeting when/where possible.  C. Stirrups used to strap ducts must be a minimum of 1 ½" in width.  D. Ductwork has minimal sag (no more than 1/2" per foot) and is supported in stirrups placed at least every 4 feet.  E. Balancing dampers are in place and are labeled and accessible per the layout drawing. Damper grills are an acceptable method for dampening.  F. Ductwork size, register and return location follows the design layout and layout is provided on site.  G. Ducts in unconditioned space are not in contact with other ducts and building components (when space allows) to avoid compressing the insulation and potential condensation.

 H. Bends in flexible duct are not less than one duct diameter at the centerline of the radius, maintaining the diameter of duct through bend.  I. Any damage to the ductwork vapor barrier jacket is repaired with UL181 tape.

 J. All unions and terminations of flexible duct jackets are sealed with mastic or UL 181 tape, fully encapsulating the insulation and connecting collar with no gaps at the ends where branches meet trunk lines, unions, or boots.  K. Insulated boots are sealed with mastic or UL 181 tape to ensure insulation is in contact with the metal boot.  L. All seams in the boot are sealed with mastic or UL 181 tape to prevent leakage inside the boot.  M. All plenums are sealed with mastic or UL 181 tape to air handler.  N. All living spaces have a return air strategy. Any room requiring more than 50 CFM's of supply air will require return air strategy (dedicated return, jump duct, or transfer grille - no door undercuts except for closets, pantries or similar small spaces).  O. When ducts are in contact with lower truss chords, inspect for full coverage with attic insulation material.

CONSTRUCTION STANDARDS CHECKLISTS | HVAC Systems | 19