Insulating Flex Duct Or Ductboard? - HVAC - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 04-27-2012, 03:44 PM   #1
Member
 
Join Date: Oct 2011
Location: Alabama
Posts: 250
Rewards Points: 188
Default

Insulating Flex Duct or Ductboard?


I asked this question a few weeks ago but only received an opinion, otherwise non definitive.

Can you add additional insulation to your existing flex duct or ductboard?

One posted opined in stating he thought you could. I've since added some faced r19 insulation to the top of my ductboard runs and will eventually add some to the sides. Otherwise, I will add more Cellulose insulation which already covers portions(bottoms) of my existing ductwork.

Anyhow, I came across a site that states you should not allow insulation to cover flex duct (see #8).

Is this really an issue or can I further insulate my ductwork?

Thanks for the input.....

Advertisement

Ralph III is offline   Reply With Quote
Old 04-27-2012, 04:56 PM   #2
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,543
Rewards Points: 4,724
Default

Insulating Flex Duct or Ductboard?


Works best if you use a face wrap, instead of an open insulation.

If flex is going to be intentionally covered with blown insulation. Cellulose is better, as it slows air movement down better. And will carry/permit less moisture to penetrate toward the duct.

Advertisement

beenthere is online now   Reply With Quote
Old 04-27-2012, 06:07 PM   #3
Member
 
Join Date: Oct 2011
Location: Alabama
Posts: 250
Rewards Points: 188
Default

Insulating Flex Duct or Ductboard?


Quote:
Originally Posted by beenthere View Post
Works best if you use a face wrap, instead of an open insulation.

If flex is going to be intentionally covered with blown insulation. Cellulose is better, as it slows air movement down better. And will carry/permit less moisture to penetrate toward the duct.
Hey Beenthere.

Can you elaborate a little more on what your saying? Also, are you recommending such as THIS refective type insulation for ductboard?

I have about 50ft (two branches) of main supply ductboard with flex duck coming off of those for individual ceiling registers. I had two large rolls of faced r19 insulation that I just rolled onto the tops of the ductboard. A portion (bottoms and partial sides) of all flex duct is already covered with cellulose blown-in insulation. I had thought to completely/mostly cover all ductboard and flex duct in cellulose insulation in hopes of raising r value.

What are the issues with this? Am I creating an issue in which moisture would collect on the ductwork because it would seem to be the opposite? BTW, I used faced insulation because I have quite a bit of that on hand.

Thanks, Ralph

Last edited by Ralph III; 04-27-2012 at 06:11 PM.
Ralph III is offline   Reply With Quote
Old 04-27-2012, 09:55 PM   #4
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,543
Rewards Points: 4,724
Default

Insulating Flex Duct or Ductboard?


I was referring to fiberglass with a foil face. But that should work.

What the article was talking about. Was the possibility of the flex duct getting cold enough for the moisture in the insulation to condense. Non faced insulation can breathe, and the moisture will condense sometimes.
beenthere is online now   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Using flex duct for return. lakeresident HVAC 3 11-14-2011 10:56 AM
Planning on New duct work..any feedback... kilosos2 HVAC 28 01-26-2011 10:21 AM
Jenn-Aire Downdraft - OEM flex duct required? Dwizzo Appliances 0 10-09-2010 05:35 PM
Metal duct or flex? smokey982 HVAC 6 08-06-2010 07:20 AM
Flex Duct Advice ssporty21228 HVAC 4 07-23-2008 09:28 PM




Top of Page | View New Posts