Foam Insulation on roof rafters

Inspecting a high end home today that was built in 2008. When i was inspecting the attic, here’s what I found. Foam insulation in the roof truss area, not the ceiling joist in the attic. Is this this practice acceptable and how??? It seems to me that you would be heating the whole attic area with no insulation in the ceiling… I need your feedback Please…




The attic is now part or the building envelope.
More to come.

What Bob said. It’s a conditioned attic.

More Info

Here’s more info.

You guys recommend open or closed cell?

It dependson the application

One question and 3 links.
Anyone know enough to actually speak about it rather than do a web search?

Use high density closed cell for conditioned attics. The open cell is not a vapour retarder and will allow vapour to diffuse to the roof sheathing.

A small house in upstate NY with full open cell foam insulation and poor interior house ventilation was a mess within 3 years. They could wring water from some of the low density foam.

Open cell passes moisture/vapor, closed cell traps it. Closed cell preferred more for exterior applications.

I know the open cell passes moisture but do you want that under the sheathing or would you wish to seal it?

Seems open would be best but am I correct?

Know if trapped that moisture breeds mold and rot.

Foam on sheathing will trap moisture between sheathing and roof.

I prefer closed cell.

I see it every now and then…
Usually high end homes…
I do not personally like it…
but …
it is what it is…

Closed cell adds structural strength. Good for extreme wind zones (like where I live).

The insulation idea is a different concept.
As you will notice from your own pictures
there is no roof ventilation
areas are all sealed…

Interesting Nick prefers closed cell however if the roof leaks will you be able to tell where from?
Will closed be more likely to promote mold?

These are questions that need to be answered for us regular guy Inspectors.:slight_smile:

We are the windy city but I hope structure does not need foam for support…

This foam subject also can apply to basements as I read both sides of the subject.
Very confusing and hard to recommend anything to the client when I read deeper into this area.