Should Polyiso Be Taped? - Insulation - DIY Chatroom Home Improvement Forum

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


Thread Tools Search this Thread
Display Modes
Old 04-19-2014, 05:08 PM   #1
Join Date: Jun 2009
Location: Timmins
Posts: 122
Rewards Points: 155

Should polyiso be taped?

A number of homes up here are retrofitted with rigid polyiso, and the local box store told me that there is concern that these panels were taped at the seams when they shouldnt of been. He said that the foil on the panels when taped acts as a second vapour barrier, trapping in moisture. Makes sense. Im sure you would lose some r value by not taping, curious if you would have higher r value with untaped polyiso, or taped XPS, of the same thickness?
wilyum is offline   Reply With Quote
Sponsored Links
Old 04-20-2014, 11:08 AM   #2
Thread killer
Join Date: May 2011
Location: Southwestern Ontario, Canada
Posts: 306
Rewards Points: 272

What do they think the foil barrier is? How thick of insulation are we talking in this retrofit? If the seams aren't sealed, you can get air leakage. If it's being installed on a house, the walls should have been checked for a vapour barrier. That said, you're in northern Ontario, vapour barrier is usually always installed inside. Should it be installed if you add a lot of insulation to the outside? IMHO, no, but depending on your AHJ, they may or may not understand why. In my area, it's easier to put up the barrier for inspection, then rip it down when its passed than to explain why you don't need it. In this case, I think the box store employee is partially right but not taping the seams isn't going to help the drying potential, if there is a problem
You can have it good, fast or cheap. Pick two.
Canucker is offline   Reply With Quote
Sponsored Links
Old 04-22-2014, 09:56 PM   #3
Registered User
Join Date: Mar 2009
Posts: 11,730
Rewards Points: 526

Risky to use foil-faced and poly... the FB needs to be thick enough for local temps per location to prevent cavity condensation of any moisture from interior/exterior, as said;

If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
17,000 dryer fires a year, when did you last clean the inside of the dryer near motor or the exhaust ducting?
Gary in WA is offline   Reply With Quote
The Following User Says Thank You to Gary in WA For This Useful Post:
Windows on Wash (04-23-2014)
Sponsored Links

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
Polyiso or XPS for Garage ceiling under drywall? Ocelaris Insulation 6 04-07-2014 08:21 PM
Polyiso foam to block, then siding, but... pillars? bluefoxicy Insulation 2 03-01-2014 03:23 PM
layered polyiso wewantutopia Insulation 5 08-26-2012 10:30 PM
Manufacture History Roofmaster417 Roofing/Siding 6 02-23-2012 02:40 AM
insulating heated garage(retrofit)- insul. & pipes KatieAK Building & Construction 0 10-25-2009 09:03 PM

Top of Page | View New Posts