Spray Foam and Fiberglass Insulation

Yesterdays inspection had an unvented attic space with spray foam insulation on the roof under side. It also had loose fill fiberglass on the attic floor. Does the added fiberglass compromise anything with the unvented attic space. Also there were a couple of spots that were open in the soffit areas where condensate lines exited through the soffit and the ceiling over the front porch had vented vinyl siding.

I recommend that you learn about this system before asking about it…
Use Google before NACHI.


page 3, para 4

Thanks David but that link has apparently been removed. Thanks anyway I’ll google for info.


Okay I got that no vapor retarder should be installed. I understand that you don’t want to trap moisture in the unvented attic space. So do you consider loose fill fiberglass to be a vapor retarder? I guess that should be my question. Some people consider loose fill fiberglass to be just a filter.

The requirement that there be no vapor retarder on the interior ceiling of the unvented
attic assembly is primarily intended to avoid trapping warm moist air in the attic area in
warm humid climates (not an issue in Washington) but also to make it clear that a vapor
retarder is not needed at the ceiling level for the unvented attic assembly application

Forgetting the link for a minute it seems to me the place should be either conditioned or unconditioned and by insulating the floor it is neither
taking into account the rafters are insulated.
The link addresses vapor retarders only so apparently the loose fill is ok as long as it does not have a vapor barrier .(is this correct) ?

I see that is correct Bob. :slight_smile:

Yes I was thinking that the loose fill fiberglass is okay but just wanted some other opinions. Now I do think that they have compromised the unvented space by allowing the porch ceiling to have vented vinyl. Since the unvented attic space is intended to part of the conditioned part of the house.

Info here might help some.