Insulating Duct Pipe Between Basement Ceiling Joists

Old 03-01-15, 05:17 AM
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Insulating Duct Pipe Between Basement Ceiling Joists

I apologize if posting in the wrong forum.

I pulled down my drop ceiling in my basement to insulate my rim joist and complete some electrical work. I have a register in the far corner of my house on the first flow that blows cold air for a good few minutes before warming up just before the furnace turns off. I would like to insulate this duct run since I have access to it. I do have one issue. I already tried insulating one run with a roll of duct wrap from Home Depot, with the foil backing. It was quite a task, fiberglass in the air and all of the flooring nails through the subfloor were catching really bad too. This section I would like to do is about 1 inch from the subfloor so I want to avoid fiberglass wrap.

Could I use Roxul Comfort Batt on both sides of the duct in between the joists? Once I pack in the Roxul what should I use to keep the Roxul from falling down over time (even if in there tight), insulation support rods 100pk from Home Depot? I also thought after packing in the Roxul and installing the rods I could staple up Reflectix Roll to close the two joists and keep the heat in?

The only other idea I had to avoid using fiberglass was cutting XPS boards the length of the joists, glue them in then cap off the bottom. I just didn't want to get my table saw out in the middle of our NE snow storms.

Let me know your thoughts. Thanks.
Old 03-01-15, 05:56 AM
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Join Date: Jul 2007
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I pulled down my drop ceiling in my basement
That statement implies that your basement is finished and the space is conditioned already. Adding insulation to a duct in conditioned space will do little to change the heating characteristics of those lines that are furthest from the main trunk. It has more to do with the thermostat reaching temperature too soon. Is the room serviced by this duct closed off from the rest of the house?

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