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

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

Reply
 
Thread Tools Search this Thread Display Modes
Old 07-26-2014, 01:51 PM   #1
Newbie
 
Join Date: Jul 2014
Location: Northern Virginia
Posts: 3
Rewards Points: 10
Default

Insulating square ducts in crawlspace


Hi all, new to the forum but hope someone can offer assistance. Background:
  • 1940s house in Northern VA
  • Vented crawlspace approx 30' x 20'
While installing some cable in the crawlspace recently, I noticed a few issues with the ducts - photos attached.

The ducts have been (more or less) sealed with mastic, but they are uninsulated and there is a little mold/mildew on the joists. I'm wondering whether I can/should insulate these ducts and if so how? I can wrap duct insulation around some of the tubular supplies, but the square ducts completely fill the space between joists.

Thanks in advance for any assistance.
Attached Thumbnails
Insulating square ducts in crawlspace-1-2cwphau.jpg   Insulating square ducts in crawlspace-2-tnpoajl.jpg   Insulating square ducts in crawlspace-3-wze1uui.jpg   Insulating square ducts in crawlspace-4-ekdsw6g.jpg  

nova_ducts is offline   Reply With Quote
Old 07-26-2014, 02:15 PM   #2
Member
 
Join Date: May 2014
Location: MO
Posts: 72
Rewards Points: 75
Default

Insulating square ducts in crawlspace


I would insulate the bottom, the joists will provide some insulating value.

Bitters is offline   Reply With Quote
Old 07-26-2014, 02:32 PM   #3
Newbie
 
Join Date: Jul 2014
Location: Northern Virginia
Posts: 3
Rewards Points: 10
Default

Insulating square ducts in crawlspace


Quote:
Originally Posted by Bitters View Post
I would insulate the bottom, the joists will provide some insulating value.
Thanks for the reply. What would be best to insulate the bottom - foam or foil-backed board?
nova_ducts is offline   Reply With Quote
Old 07-26-2014, 03:48 PM   #4
Member
 
Join Date: May 2014
Location: MO
Posts: 72
Rewards Points: 75
Default

Insulating square ducts in crawlspace


I would use foam and go from joist to joist. Don't forget the hangers, they look like a spike. Then use foil tape at the joints and hangers.
Bitters is offline   Reply With Quote
The Following User Says Thank You to Bitters For This Useful Post:
nova_ducts (07-26-2014)
Old 07-27-2014, 05:19 PM   #5
Newbie
 
Join Date: Jul 2014
Location: Northern Virginia
Posts: 3
Rewards Points: 10
Default

Insulating square ducts in crawlspace


Quote:
Originally Posted by Bitters View Post
I would use foam and go from joist to joist. Don't forget the hangers, they look like a spike. Then use foil tape at the joints and hangers.
Okay, just picked up some of these 2" x 4' x 8' foam boards. Unfortunately no spike fasteners available - the salesperson recommended just using liquid nails or regular nails with washers to secure the foam to the joists. Is there a risk of condensation pooling on top of the foam board if it's glued to the bottom of the joists and effectively touching the duct?

Thanks again.
Attached Thumbnails
Insulating square ducts in crawlspace-02bbc414-1d7e-4d09-af01-10f329edfb7c_1000.jpg  
nova_ducts is offline   Reply With Quote
Reply

Tags
crawl space, duct, insulation, mildew, mold


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Crawlspace mold and fungus WillK General DIY Discussions 4 12-18-2012 09:53 AM
Crawlspace update WillK Insulation 2 05-01-2012 09:18 AM
Can you glue to HVAC Ducts tro0925 HVAC 3 03-24-2011 03:31 PM
Insulating Ducts... Did i do this right? jdm001 HVAC 2 01-25-2011 06:34 AM
properly insulating a crawlspace mcvane Building & Construction 5 02-01-2010 08:56 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.