Open cell spray foam application

Hi guys,

I am questioning the application of open cell spray foam insulation on this 2x4 frame house.
As we know it, in order for insulation (fiber glass, mineral wool, cellulose) to be effective, the thermal barrier (insulation) and the air barrier (drywall in my part of the country being Houston) need to be in direct.
So, my dumb question would be, does this also apply to open cell spray foam insulation?
The application on this new build was in my mind improper as the foam was not sprayed in the entire depth of the studs and rafters, leaving big gaps in between each studs and the drywall.
Any advice, documentation on consequences of improper installation would be much appreciated. Thanks.

not effective unless it completely covers the framing. this will most likely shrink away from the framing in a few weeks/months and render it basically worthless. Icynenne has a good installation guide on the web you can review.

Don’t believe that’s how the story goes!!!

ESR-1826 ICC-ES Evaluation Report*](

Thanks for the link Marcel
William, thanks for the comment. I was reading somewhere that open cell spray foam didn’t have to the full depth of the stud (although in this case, the installation thickness is not even close to 3.5"). Of course I can’t find that article anymore.
An HI, how does the story go? 'Cause that response wasn’t very helpful to either me or any other person who wants to learn…

Permeability in the Link above post.

Yep, the insulation needs to be at 3.5" to be considered permeable.

Unlike the closed cell SPF which the minimum is 2".
It has a permeance rating of less than 1.0 when applied at 2 inches

That’s how the story goes!

I think you mean the open cell Icynene insulation needs to be 3.5" thick to be considered fully **air **impermeable as mentioned in Section 3.4 of the reference document. They were not talking of vapour permeance in the document.

In your area, they don’t call for interior vapour barriers in housing but for no vapour barreirs and air tightness for moisture control/energy savings. Some jurisdictions may call for exterior vapor barriers and air tightness.

Yes, air permeable is what I meant.
The article I read was saying that due to its nature, the open cell spray foam (thermal barrier) did not have to be in direct contact with the drywall (air barrier) in order to be effective, unlike mineral wool and other insulations. Would anybody have data on that, perhaps thermal images?