0 Helpful?

Hybrid Wall - Closed Cell Spray Foam Flash w/ Exterior Insulated Sheathing

As I was searching through the various posts related to the use of insulated sheathing on the exterior envelope I have not seen anything for or against the use of exterior insulation in combination with 2# closed cell spray foam (1-2" thick) on the interior cavity. My first thoughts were combination may allow you to reduce the thickness of the exterior insulation, aleviating some of the window/trim detail concerns and still help you reduce the likelihood of the dew point occuring at the sheathing (both are basically vapor impermeable). My concerns is related to the issues that may occur if the tape at the seams of the exterior insulation fails or water/moisture finds its way somehow between the two insulations and has no way to escape, thus rotting out the structural sheathing sandwiched in between? I think i know the answer is to probably not to use this system because of this concern, but I wanted to throw the question out there to get the thoughts of the community. Thanks in advance for your input.

Asked by Michael Burke
Posted Dec 20, 2012 4:21 PM ET
Edited Dec 20, 2012 4:23 PM ET


1 Answer

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Other Questions in Energy efficiency and durability

Low profile cans /speakers below closed cell in a flash and batt roof.

In Energy efficiency and durability | Asked by Chris B | Oct 26, 16

More rim joist insulating questions

In Energy efficiency and durability | Asked by Joe Sweeney | Oct 25, 16

Air sealing attic: materials and fire safety

In Energy efficiency and durability | Asked by Sam Smith | Oct 25, 16

Risky assembly

In Energy efficiency and durability | Asked by Jonathan Lawrence CZ 4A New Jersey | Oct 25, 16

Design help for combined DHW and Space Heating

In Mechanicals | Asked by Torsten Budesheim | Oct 26, 16
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!