FRP Fabrication Standards

UnderDuct Receives Code Approval from ICC 

“UnderDuct is an ICC approved product, properly tested to the applicable standards of LC1014.”

Monoxivent has received confirmation from ICC Evaluation Service, LLC (ICC-ES), that its UnderDuct Fiberglass Reinforced Plastic duct is approved with the provisions of the:

  • 2012 and 2009 International Mechanical Codeᴿ (IMC)
  • 2012 and 2009 International Residential Codeᴿ (IRC)
  • 2012 and 2009 Uniform Mechanical Codeᴿ (UMC)*
  • 2010 and 2007 California Mechanical Codeᴿ (CMC)

*Uniform Mechanical Code is a copyrighted publication of the International Association of plumbing and Mechanical Officials.

This confirmation, as evidenced in ICC-ES listing PMG-1171, provides guidance to code officials faced with approving the use of UnderDuct under these codes.

The listing is available online at

Read Monoxivent's Summary

UnderDuct Passes UL 181 Mold Growth Testing 

July 29, 2014

Subject: Report of Mold/Growth and Humidity Test on UnderDuct Composite samples as submitted by Monoxivent/UnderDuct/Corrosion Composites

“This is a report summarizing the results of tests conducted under the Commercial Inspection and Testing Services (CITS) program identified as Assignment No.. 4786337200. Under this investigation, three samples each at  4 in. by 4 in. size were tested in accordance with the  Mold/Growth and Humidity test of  UL181, 11th Edition.”

Read the Report

Corrosion Composites Standards 

Corrosion Composites by Monoxivent offers a full line of corrosion resistant fiberglass products. Our products are designed and fabricated in accordance with industry standards providing the end user with dependable quality solutions, and the right material of choice for a variety of applications. Monoxivent’s manufacturing source provides over 90,000-sq. feet of production space, modern equipment, and over 50 years of experience within the FRP industry.

ASTM and SMACNA standards are the benchmark for fabrication of our FRP products, including:

ASTM (American Society of Testing and Materials):

  • ASTM D3299, Standard Specification for Filament-Wound Glass-Fiber-Reinforced Thermoset Resin Corrosion-Resistant Tanks
  • ASTM D3982, Standard Specification for Contact Molded Fiberglass (Glass Fiber Reinforced Thermosetting Resin) Ducts
  • ASTM D4097, Standard Specification for Contact-Molded Glass-Fiber-Reinforced Thermoset Resin Corrosion-Resistant Tanks
  • ASTM D6041, Standard Specification for Contact-Molded “Fiberglass” (Glass-Fiber-Reinforced Thermosetting Resin) Corrosion Resistant Pipe and Fittings
  • ASTM C582, Standard Specification for Contact-Molded Reinforced Thermosetting Plastic (RTP) Laminates for Corrosion-Resistant Equipment

SMACNA (Sheet Metal and Air Conditioning Contractors’ National Association): 

SMACNA, Thermoset FRP Duct Construction Manual 

UD Standards for Quality Assurance

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.

RADCO Code Test Report

Resources, Applications, Designs, and Controls, Inc. Listing and Testing Division

Testing for UnderDuct Fiberglass Reinforced Plastic per ICC-ES PMG LC1014

Read the RADCO Test Report