American Made Fiberglass Reinforced Plastic

Buy American Act

UnderDuct, by Monoxivent, is in compliance of the Buy American Act, Sec. 1605.  Please contact Monoxivent staff with any questions pertaining to this act: 877-608-4383.

The act language follows:


(a) None of the funds appropriated or otherwise made available by this Act may be used for a project for the construction, alteration, maintenance, or repair of a public building or public work unless all of the iron, steel, and manufactured goods used in the project are produced in the United States.

(b) Subsection (a) shall not apply in case or category of cases in which the head of the Federal department or agency involved finds that –

  • (1) applying subsection (a) would be inconsistent with the public interest;
  • (2) iron, steel, and the relevant manufactured goods are not produced in the United States in sufficient and reasonably available quantities and of a satisfactory quality; or
  • (3) inclusion of iron, steel, and manufactured goods produced in the United States will increase the cost of the overall project by more than 25 percent.

(c) If the head of a Federal department or agency determines that it is necessary to waive the application of subsection (a) based on a finding under subsection (b), the head of the department or agency shall publish in the Federal Register a detailed written justification as to why the provision is being waived.

(d) This section shall be applied in a manner consistent with United States obligations under international agreements.

Benefits of FRP

Corrosion Resistant

UnderDuct’s Fiberglass Reinforced Duct is specifically designed to withstand the harsh underground environment. Our FRP duct stands up to water, temperature changes and acidic soil conditions. In very wet or corrosive environments, UnderDuct is the clear choice over stainless steel, galvanized, PVC, or PVC coated galvanized.

High Strength yet Lightweight

Filament wound FRP Composites have a higher strength-to-weight ratio than steel. Being a structural material, large lightweight fiberglass duct sections can be shop fabricated and shipped to the jobsite for easy installation. Lightweight components also save on transportation and installation costs. UnderDuct does not require concrete encasement. When buried in compacted sand or pea gravel UnderDuct does not require hold downs.

Shop Fabrication

UnderDuct assemblies are built to approved shop drawings. Shop assembled sections can be in the range of 20’ long allowing as few field joints as possible. Not only does this lessen shipping costs, it also assures better quality control and cuts expensive field installation costs.


Unlike metal, UnderDuct is inherently non-conductive.

Minimal Maintenance

UnderDuct is built to last the life of the building. Even after a flood or a sprinkler system release UnderDuct can be pumped out with no ill effects.

Fire Resistant

All surfaces of UnderDuct and fittings, as a finished composite, meet the Flame and Smoke requirements of the Class 1 duct per UL 181 and UMC 10-1. Verifications of performance are done by an ASTM E-84 testing laboratory, recognized by the following building code organizations under the Council of American Building Officials: ICBO; BOCA; SBCCI.

Green Building with FRP

Underground FRP Duct is Environmentally Sound

Due to the ‘green’ aspects of our fiberglass reinforced plastic underslab duct, FRP duct is a key component of sustainable building. The quality and strength of our FRP duct means a longer life, which saves resources, and maximized airflow uses energy more efficiently.

UnderDuct Green Benefits:

  • Smooth and improved air flow
  • Energy savings with insulated FRP duct
  • Maximizes air flow and efficiency
  • Resistance to mold, corrosion, leakage, moisture damage
  • 824 low smoke and flame – Class 1 Rating
  • Long-life duct
  • Energy savings through Displacement Ventilation Design
  • Allows for “open concept” design in buildings
  • Laminated joints for complete seal