You are currently on the SWS 2017 legacy website. To view the current 2020 SWS website, please visit https://sws.nrel.gov.

The SWS 2017 website will be taken down in September 2022. You can access an archive of 2017 specifications from the 2020 SWS website under News & Updates.

3.1601.6 Preparation and Mechanical Fastening—Low Rise

Topic:

Ducts

Subtopic:

Duct Preparation

Desired Outcome:

Ducts and plenums are properly fastened to prevent leakage

For supporting material, see Referenced Standards.

Multifamily Homes

	Title	Specification(s)	Objective(s)
	3.1601.6a Preparation	Surrounding insulation will be cleared to expose the joints being sealed Duct surface that accepts sealant will be cleaned	Gain access Achieve proper adhesion for airtight seal
	3.1601.6b Metal to metal	Ducts will be fastened with a minimum of three equally spaced screws or acceptable mechanical connections	Ensure joints are durable
	3.1601.6c 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 or mechanical band, and sealed with approved mastic and UL181B tape	Ensure joints are durable Reduce air leakage
	3.1601.6d Duct board to duct board	Joints will be fastened with a clinch stapler, rated tape, and mastic	Ensure joints are durable Reduce air leakage
	3.1601.6e Duct board to flexible duct	An appropriate take-off collar in accordance with NAIMA NAIMA North American Insulation Manufacturers Association, www.naima.org standards will be used and sealed with approved mastic	Ensure joints are durable Reduce air leakage
	3.1601.6f Metal plenum to air handler cabinet	Plenum will be fastened with a minimum of three equally spaced screws on each side Canvas connection between plenum and unit will be installed so that it does not reduce the inside dimensions of the duct	Ensure joints are durable Reduce air leakage Optimize airflow
	3.1601.6g 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 joints are durable Reduce air leakage
	3.1601.6h Terminal boot to wood	Screws or nails will be used to fasten boot to wood Seams and boot to subfloor will be sealed with mastic	Ensure joints are durable Reduce air leakage
	3.1601.6i Terminal 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 Seams of boot will be sealed with mastic Boot to gypsum will be sealed with caulk in accordance with local code and standards	Ensure joints are durable Reduce air leakage
	3.1601.6j Duct board to flex	An appropriate take-off collar in accordance with NAIMA NAIMA North American Insulation Manufacturers Association, www.naima.org standards will be used	Ensure joints are durable Reduce air leakage
	3.1601.6k Replacement of insulation	Insulation will be returned or replaced with equivalent R-value	Maintain insulation value