Single Wall & Double Wall UnderDuct Solutions

UnderDuct is leading the way for code compliant LEED driven underground HVAC systems. UnderDuct is a corrosion resistant, high strength, light weight, Class 1 duct material, per NFPA 90. UnderDuct is ideal for displacement ventilation, allowing for the most economical long term energy savings. UnderDuct is shop fabricated with a minimum number of field joints. Monoxivent has a nationwide network of sales representatives and a top-tier inside support staff that provides engineering, design, sales, service, and marketing. UnderDuct is offered both in single wall and pre-insulated double wall construction to meet any ventilation needs. UnderDuct can be used in above ground applications, not just underground. UnderDuct also comes in a variety of configurations to fit your project needs.

UnderDuct Single Wall Solutions

Our Class 1 rated single wall duct, meets 25/50 flame/smoke requirements of ASTM E 84. Monoxivent UnderDuct 824 Low Smoke has been approved for underground applications. It is an excellent choice for corrosive environments where flame and smoke development are a concern, such as laboratories and swimming pools. Monoxivent’s single wall register boot (below) is shown during installation. The corrosion resistant boots are high strength and meet the same standards as typical single wall UnderDuct. Register boots are available in double wall construction as well.

UnderDuct Double Wall Solutions

Double wall Monoxivent UnderDuct, also a Class 1 rated duct, will eliminate any thermal losses and save time and money compared to insulating on site. When supplied with the standard 1” insulation, the duct has a k factor of 0.16 and an R Value of 6. Also available in R-10 and R-14 by request.

Double Wall Insulated UnderDuct fully complies with the latest version of the International Energy Conservation Code (IECC) which requires specific R-values determined by ASTM testing methods.

Above Ground Applications For UnderDuct

UnderDuct was originally designed for direct burial without concrete encasement, however it has also been used in above ground applications due to its’ corrosion resistance and low smoke/low flame rating.

FRP Configurations


Round, rectangular and oval are typical filament wound construction shapes. Upon request, shapes such as triangular and others are available. Qualified Monoxivent staff is available for designing projects requiring non-standard construction.


Duct diameters are available from 2-inch through 14-feet, and rectangular sizes as required for your projects. Monoxivent’s 824-API pre-insulated double wall duct is also available in the above ranges.