What materials are approved for sealing duct board?

What materials are approved for sealing duct board?

• A. Duct tape only
• B. Pressure sensitive or heat activated aluminum foil tape, glass fabric tape, and mastic
• C. Silicone caulk only
• D. Vinyl tape only

Answer: (B)

Sealing duct board requires materials that create a durable, airtight joint and are rated for use on HVAC ductwork. The approved options are pressure-sensitive or heat-activated aluminum foil tape, glass fabric tape, and mastic. These materials hold up to duct temperatures and humidity, bond well to both metal and the fibrous duct board, and provide a long-lasting seal. Duct tape and vinyl tape aren’t suitable for this purpose because they tend to fail under the environmental conditions inside ducts, such as temperature changes and moisture, leading to leaks. Silicone caulk alone isn’t listed as an approved sealant for duct board joints; it may not provide the necessary adhesion and durability when used by itself. Using the combination of foil or glass fabric tape with mastic delivers a robust, code-appropriate seal.

Sealing duct board requires materials that create a durable, airtight joint and are rated for use on HVAC ductwork. The approved options are pressure-sensitive or heat-activated aluminum foil tape, glass fabric tape, and mastic. These materials hold up to duct temperatures and humidity, bond well to both metal and the fibrous duct board, and provide a long-lasting seal.

Duct tape and vinyl tape aren’t suitable for this purpose because they tend to fail under the environmental conditions inside ducts, such as temperature changes and moisture, leading to leaks. Silicone caulk alone isn’t listed as an approved sealant for duct board joints; it may not provide the necessary adhesion and durability when used by itself. Using the combination of foil or glass fabric tape with mastic delivers a robust, code-appropriate seal.