Underground HVAC ductwork properties must assure that the product has structural integrity throughout all of the component sections and connections and resist expansion/contraction.  It must have a high degree of thermal resistance to thermal transmittances through its wall layers (U Value).  To insure life safety, underground ductwork must exhibit a flame spread of less than 25 and smoke spread of less than 50, commonly referred to as 25/50.

What are the standards for assurance?  Listing Criteria #LC1014, set by the ICC, (International Code Council Evaluation Service) for underground ductwork and the independent testing laboratories that administer the tests and certify the result, are the basis for approved products to be included in the International Building Code (IBC), International Mechanical Code (IMC) and the International Residential Code (IRC).  Currently, these codes are published in the 2012 Edition.  Products tested to the ICC standards include the provision for yearly inspection of the manufacturing facilities as a part of the quality assurance for compliance.  UnderDuct is an approved product and is listed in ICC-ES listing PMG-1171.

ICC Evaluation Service PMG Listing Criteria For Underground Plastic Air Ducts LC1014 is the standard to which UnderDuct has been tested and certified to meet and exceed the following:

ASTM D2412 – Standard Test Method for Determination of External Loading Characteristics of Plastic Pipe by Parallel-Plate Loading.  UnderDuct sections, fittings and connections are filament wound set in resin structures to create a monolithic duct system which allows UnderDuct to exceed the requirement of the standard.

ASTM E84 – Standard Test Method for Surface Burning Characteristics of Building Materials.

Only Underduct has passed this test and classifies this as a Class 1 by virtue of the actual resin used in its construction.  Other manufacturers use metallic liners on the interior to pass this test or don’t meet this standard at all. 

UL 723 – Test for Surface Burning Characteristics of Building Materials

Underduct far exceeds any competitor’s product for the same reasons as it does for the ASTM E84 test.

ASTM C518 – Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus.

Underduct has been properly tested using the ASTM C518 test method, which determines the actual R value of a material; Underduct is documented to have an R-6 insulation value.  The International Energy Conservation Code (IECC) REQUIRES specific R-values for buried duct determined by ASTM test methods. Double Wall Insulated Duct is in FULL COMPLIANCE with the IECC. 

UL 181 – Mold Growth and Humidity Test

Leakage Testing:
UnderDuct is approved for burial (6′) below the Base Flood Elevation.

As a result of the above tested approvals, UnderDuct meets, exceeds and is approved to the standards of the California Energy Commission Title 24.  The insulating foam used in the double wall construction of UnderDuct is licensed by The Bureau of Electronic and Appliance Repair, Home Furnishings and Thermal Insulation.  The new California Energy Code became effective January 1, 2014.  UnderDuct is the only product for direct burial underground ductwork to currently meet the new California Code and demonstrates Monoxivent’s commitment to the highest quality standards.

Test results for the standards listed above can be found here.