How to Insulate Ductwork | Ask This Old House

Richard Trethewey helps a homeowner insulate his ductwork. (See below for a shopping list, tools, and steps.) SUBSCRIBE to This Old House: http://bit.ly/SubscribeThisOldHouse Shopping List for How to Insulate Ductwork: Foil tape [https://amzn.to/2kWBZ1s], for sealing ducts Duct mastic [https://amzn.to/2mXAeSg], used to seal duct joints Foil tape with mastic membrane [https://amzn.to/2lsjrpT], for sealing ducts 1-inch foil-faced fiberglass batt insulation [https://amzn.to/2kVm9UP], used to insulate ducts Preformed fiberglass duct insulation [https://amzn.to/2lpqGyX], for insulating ducts Tools for How to Insulate Ductwork: 2-inch paintbrush [https://amzn.to/2mrMB8Z], for applying duct mastic Utility knife [https://amzn.to/2mWQ0gc], used to cut insulation Steps for How to Insulate Ductwork: 1. Check the speed of the blower motor on the furnace. If necessary, switch the wires to reduce the blower to its lowest speed. 2. Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct. 3. Use a paintbrush to apply duct mastic to the joints where an elbow connects to a duct. 4. Use a utility knife to cut foil-faced fiberglass insulation to the proper size. 5. Wrap the insulation around the duct, and then pinch the seam closed. Secure the insulation with short strips of foil tape. 6. Apply a long strip of foil tape along the seam in the insulation. Repeat to insulate the remaining ducts. 7. To install preformed duct insulation, start by disconnecting an elbow to expose the end of the duct. 8. Snap a plastic cap onto the duct end, then slip the preformed insulation over the duct. 9. Gently pull the insulation over the entire length of duct. Additional advice was provided by Air Purchases, Inc. [https://www.airpurchases.com/] Richard used mastic paste to seal the joints between ducts, in this case Hard Cast Duct Seal 321 by Carlisle HVAC [https://www.carlislehvac.com/]. He also used Nashua foil tape designed for sealing ducts, manufactured by Berry Plastics Corporation [http://www.nashuatape.com/]. Finally, Richard installed Owens Corning [https://bit.ly/2UxxHf4] 1.5 inch thick fiberglass insulation around the ductwork. This insulation has an FSK foil-facing and provides an R-value of 4.2. About Ask This Old House TV: Homeowners have a virtual truckload of questions for us on smaller projects, and we re ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook. Looking for more step by step guidance on how to complete projects around the house? Join This Old House INSIDER to stream over 1,000 episodes commercial-free: https://bit.ly/2GPiYbH Plus, download our FREE app for full-episode streaming to your connected TV, phone or tablet: https://www.thisoldhouse.com/pages/streaming-app Follow This Old House and Ask This Old House: Facebook: http://bit.ly/ThisOldHouseFB Twitter: http://bit.ly/ThisOldHouseTwitter http://bit.ly/AskTOHTwitter Pinterest: http://bit.ly/ThisOldHousePinterest Instagram: http://bit.ly/ThisOldHouseIG http://bit.ly/AskTOHIG For more on This Old House and Ask This Old House, visit us at: http://bit.ly/ThisOldHouseWebsite How to Insulate Ductwork | Ask This Old House https://www.youtube.com/user/thisoldhouse/