Double Wall Duct

Commonly specified for exposed duct settings in schools, hospitals, and laboratories, double wall duct has a clean look that is much more aesthetically pleasing than externally insulated.

Double wall duct is constructed with a fiberglass insulation layer between a solid metal outer shell and either a perforated or solid inner shell.

Acoustical double wall duct is built with a solid outer shell and a perforated inner shell to effectively reduce system noise.

Thermal control double wall is built with solid inner and outer shells for assured thermal conductivity and vapor barrier integrity.

Products Product Description 

Perforated Metal

Perforated-Product22 Gauge Galvanized Perforated Sheet, 3/32" Round Holes on 3/16" Staggered Centers (23% Open Area), to be used as the inner layer/shell in conjunction with a solid Galvanized outer layer and 1" Insulation in the middle to meet SMACNA specs for noise control.

Conklin stocks in 60" x 120" Sheet and 60" wide Coils. Also available in 5.394" wide Slit Coils for the inner layer of Double Wall Spiral Pipe.

To determine the weight on 22 Gauge Perforated Coils, figure based on .96-lbs per SQ-FT. (8,000 SQ-FT Coil of 22 Gauge 60" Wide weighs 7,680-lbs).
Spec Sheet
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Unfaced Duct Liner

Jm-UnfacedJohns Manville’s Spin Glass Unfaced Liner is the choice for most Spiral Pipe manufacturers. It’s basically the Duct Liner without the facing and used for both Round and Rectangular Double Wall Pipe.Spec Sheet
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MylarWe stock a 5-ft x 100-ft. roll of 3-mil. Mylar for use in Rectangle Double Walled Duct as a vapor barrier, applied between the Perforated Metal and the Insulation to prevent Insulation fibers from entering the air stream.Item Codes

Spiracoustic Liner

Spiracoustic-LinerJM Spiracoustic Plus is an interior Duct Liner system engineered and designed to provide industry leading acoustical and thermal performance for Spiral Duct and Fittings.Spec Sheet
Video Demo
Item Codes

Double Wall Duct with Perforated Inner Wall

Double-Wall-Spiral-PipeDouble Wall Spiral Pipe with Galvanized 5.394" Slit Coil, Unfaced Liner and 5.394" 22 Gauge Perforated Inner Section.

For Double Wall Round or Rectangular Duct, a Perforated Inner wall provides better sound attenuation than a solid inner wall; Unfaced Liner provides better sound attenuation than standard Duct Liner with a mat facing although for Double Wall jobs in which thermal specs are primary focus, either unfaced or faced (standard Duct Liner) is acceptable

Double Wall Duct with Solid Inner Wall

Double-Wall-Spiral-PipeDouble Wall Spiral Pipe with Solid inner wall; there's less sound attenuation using a solid inner wall in place of a perforated inner wall however for jobs that are specifying Double Wall for thermal requirements (avoiding condensation for example), the solid inner wall is commonly specified.