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Silver foil tape roll on a 3 inch core, 48mm wide by 100 ft long

NASHUA

NASHUA FoilMastic Butyl Rubber Sealant Tape 367-17 Silver 48mm x 100 ft

SKU CH-F5CE-PAZMJ

UL 181B-FX listed foil tape with 15 mil butyl rubber adhesive seals HVAC ducts, gutters and roofing instantly

  • TypeFoil Tape
  • ColorSilver
  • UL 181B-FX listed for code-compliant HVAC sealing
  • Aggressive butyl mastic delivers instant air-tight and water-tight seal
  • Conformable 2 mil foil fits round, square and odd-shaped ducts
  • Low VOC content supports LEED EQ Credit 4.1 requirements
  • Resists moisture, solvents, flame spread and high temperatures

HVAC Duct Sealing Tape

Nashua 367-17 FoilMastic is a UL 181B-FX listed foil tape built for indoor and outdoor HVAC ductwork. The 2 mil aluminum foil backing carries a 15 mil butyl rubber mastic adhesive that creates an instant water and air-tight seal. It handles low, medium, and high pressure systems up to 10-inch w.g. and meets SMACNA seal classes A, B, and C. Professional installers use it on sheet metal, flexible duct, gutters, and roofing seams.

Thermal And Moisture Performance

The butyl mastic adhesive resists moisture, solvents, humidity, and flame spread while maintaining bond strength across temperature swings. Conformable dead-soft foil wraps tight radii and odd-shaped fittings without bridging or tenting. Low VOC content supports LEED EQ Credit 4.1 compliance on registered projects. The UL 181B-FX listing confirms code acceptance for duct closure in conditioned and unconditioned spaces.

Upgrade From Cloth Duct Tape

Cloth-backed duct tape dries out, delaminates, and fails pressure tests over time; this foil-butyl laminate does not. The jump is worth it when the specification calls for UL 181B-FX listing, SMACNA pressure classes, or LEED documentation. It is not for buyers who need a repositionable masking tape or a thin foil tape without heavy mastic adhesive.

Highlights

  • UL 181B-FX listed for code-compliant HVAC sealing
  • Aggressive butyl mastic delivers instant air-tight and water-tight seal
  • Conformable 2 mil foil fits round, square and odd-shaped ducts
  • Low VOC content supports LEED EQ Credit 4.1 requirements
  • Resists moisture, solvents, flame spread and high temperatures

Specifications

TypeFoil Tape
ColorSilver

Questions about this item

How do I apply the 48mm wide tape so the butyl rubber adhesive bonds properly?

Remove the LDPE release liner, press the 2 mil aluminum foil firmly onto the clean duct or metal surface, and smooth it with a roller to activate the 15 mil mastic layer for an instant air-tight seal.

Will the butyl rubber adhesive dry out or need re-taping after a few seasons?

The butyl mastic stays flexible and resists moisture, solvents, humidity and temperature cycling, so it does not dry out or require scheduled replacement under normal HVAC service.

At what static pressure will the seal on rectangular ductwork reach its limit first?

The tape is rated to SMACNA 10-inch w.g. pressure class, so sustained pressures above that level are the first limit encountered on sealed seams.

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