3.1601.5 Preparation and Mechanical Fastening

Topic:

Ducts

Subtopic:

Duct Preparation

Desired Outcome:

Ducts and plenums properly fastened to prevent leakage

Manufactured Housing

	Title	Specification(s)	Objective(s)
	3.1601.5a Preparation	Surrounding insulation will be cleared to expose joints being sealed; salvage for reuse if possible Duct surface to receive sealant will be cleaned	Gain access while maintaining insulation value Achieve proper adhesion for airtight seal when needed to ensure a tight fit to the framing structure and ensure the register can be removed and reinstalled by the dwelling occupant
	3.1601.5b Metal to metal	Ducts will be fastened with a minimum of three equally spaced screws	Ensure durable joints
	3.1601.5c 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 For oval flexible duct to metal connections, tie bands cannot be used; appropriate mechanical fastener will be used All connections, regardless of fastener, will be sealed	Ensure durable joints
	3.1601.5d Duct board to duct board	Joints will be fastened with outward clinching (stitch) staples and c-channels if possible	Ensure durable joints
	3.1601.5e Duct board to flexible duct	Metal take-off collar specifically designed for the thickness of the duct board will be used All finger tabs will be bent down securely Finger tabs will be longer than the thickness of the duct board and the shank will not extend beyond the thickness of the duct board There will be an internal metal backer inside the duct board through which three evenly spaced screws can be secured; the metal backer will not interfere with air flow	Ensure durable joints Prevent the collar from moving into or out of the duct board or slipping
	3.1601.5f Duct board plenum to air handler cabinet	Flange/c-channel will be fastened with screws with the duct board installed between c-channel flanges Duct board plenum will be connected to air handler plenum with flexible duct in upflow units	Ensure durable joints
	3.1601.5g Boot to wood	Predrill for screws or use ring shanked nails to fasten boot to wood	Ensure durable joints
	3.1601.5h Boot to gypsum	If accessible, boot hanger will be fastened to adjacent framing with screws or nails Boot will be connected to boot hanger with screws If inaccessible, boot will be fastened to gypsum with a durable, adhesive sealant	Ensure durable joints
	3.1601.5i Duct board to flex	Metal take-off collar with a hip and an internal metal backer will be used Take-offs will be in accordance code requirements	Ensure durable joints