3.1601.1 Preparation and Mechanical Fastening

Duct Preparation
Desired Outcome: 
Ducts and plenums properly fastened to prevent leakage

Type and R-value of existing duct insulation (e.g., fiberglass, stone wool, asbestos) will be identified as will the location of vapor retarders, if any

If asbestos insulation was used, it will not be disturbed; consult with an asbestos abatement expert for removal

Surrounding insulation will be cleared to expose joints being sealed

Duct surface to accept sealant will be cleaned

Insulation will be returned or replaced with equivalent R-value

Gain access while maintaining insulation value

Achieve proper adhesion for airtight seal

Metal to metal

Round ducts will be mechanically fastened to maintain alignment

Other shaped ducts will be securely fastened and sealed with welds, gaskets, mastics (adhesives), mastic-plus-embedded-fabric systems, or tapes

Ensure durable joints

Flex to metal

Joints will be fastened with tie bands using a tie band Tie band A strap, often made of nylon, that mechanically squeezes a flexible duct to a fitting. Must have a minimum performance temperature rating of 165° (per UL 181A-type test) and a minimum tensile strength rating of 50 pounds tensioning tool

Ensure durable joints

Duct board to duct board

Joints will be fastened with clinch stapler

Ensure durable joints

Flexible duct to duct board

Metal take-off collar will be used and attached in accordance with IRC IRC International Residential Code

Ensure durable joints

Metal plenum to air handler cabinet

Plenum will be mechanically fastened

Ensure durable joints

Duct board plenum to air handler cabinet

Termination bar or metal strip will be fastened with screws

Duct board will be installed between the screw and the termination bar

Ensure durable joints

Boot to wood

Screws or nails will be used to fasten boot to wood

Ensure durable joints

Boot to gypsum

Boot hanger will be fastened to adjacent framing with screws or nails

Boot will be connected to boot hanger with screws

Integral snap boots will be installed

Ensure durable joints

Flex to duct board

Take-offs will be in accordance with IRC IRC International Residential Code and applicable local code

Ensure durable joints