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.
Answered by Martin Holladay
Posted Dec 20, 2012 5:41 PM ET

Other Questions in Energy efficiency and durability

Insulating block walls

In GBA Pro help | Asked by man of steele | Mar 20, 18

Taping of Roof Sheathing / Wall to Ceiling Vapor Barriers

In Green building techniques | Asked by Steve Mackay | Mar 21, 18

Brick Ledge help with Rigid Foam Over CMU

In General questions | Asked by Wayne321 | Mar 20, 18

ERV with HEPA filtration options

In Mechanicals | Asked by m4tr1x | Mar 20, 18

Ideal window depth to minimize window perimeter thermal bridging through frame

In Green building techniques | Asked by user-7038920 | Mar 21, 18
Register for a free account and join the conversation

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