I wouldn’t be happy with that either as air does travel through fiberglass insulation. Foam is its own air barrier but not fiberglass. If the insulation was to the flat part of ceiling the open attic areas would be fine but to the deck creates a problem.

you need to find out what code is for your area. Here we operate under six sided system meaning all six sides of insulation need an air barrier with attics excluded and allowed to be five sides but your knee walls are only four sides(top, bottom, and sides). Call your building department and find out what code is and maybe the inspector just missed noticing it.

Good luck!

Barriers are between conditioned and unconditioned spaces. It sounds as though all of these are unconditioned spaces.

It sounds as though all of these are unconditioned spaces.

The why bother putting up insulation? Something's not right there.

Building materials cost has increased greatly during the past few months. I sense the builder is trying to cut costs. You need to find verify the building code ASAP.

IRC (International Residential Code) is pretty much everywhere now. If the AHJ has addendums to IRC, with regard to garage-dwelling separation it would be stricter (Santa Cruz does not). Understand there is a difference between being fire rated vs fire separated, the requirements on garages is not as strict as you might guess, it is only fire separation.

"said there doesn't need to be a wall between the attic of the garage and the attic of the house."

That depends. If the garage is to have a 1/2" drywall ceiling, then no wall separating the house attic from the garage attic is required above this drywall ceiling. The attic can continue uninterrupted across the entire footprint. However, if the garage ceiling is exposed and open, then the 1/2" drywall from the separating house wall should continue up to the underside of roof sheathing to section off the attic space [IRC R302.6]. Stricter adoption would typically require 5/8" Type X everywhere or on additional walls.

"saying that there doesn't need to be a wall between the attic of the house and the "attic" of the outside covered porch"

Correct. However, this might vary on the interpretation of the code inspector. He may consider the use of the porch (e.g. BBQ using fire), or the finish of the ceiling, or the size of the overhang, or distance to property line, to require a fire separation in the attic.

______________

As far as the insulation:

- There is opportunity to use batt insulation as fireblocking to prevent unobstructed cavity access up to the attic. However, I do not believe you have that situation here, and if you did, it needs to be securely retained, which does not appear to be.

- More importantly, if you have batt insulation in the rafter plane instead of the ceiling plane, you need baffles for passive venting, which I do not see.

- The minimum value for Santa Cruz, AZ is R-38 for ceiling insulation value. That would require batts 12" thick, which will not hold between 2x4 truss top chords and from the pics it looks a bit skinnier than 12".

- Here is the link to Santa Cruz county AZ code adoption for reference: Santa Cruz County AZ Codes

Thanks for all the helpful information, everyone! I'm going to stop at the building department today and find out. 3onthetree - thank you so much for the Codes link and for really helpful information!

With batt insulation, you need to vent the underside of sheathing, in between the insulation and sheathing. Period.

Also depending on the SF of your attic there is a “draftstopping” requirement to section off spaces. “Draftstopping“ is a different construction from fireblocking or fire separation, it’s in building code & life safety code. You would have to check if your attic size falls into the range where draftstopping is required. It isn’t fire resistant but is a physical barrier

Draftstopping <1000sf is only within interstitial spaces between usable floors, not within the roof (attic) space.

Learn the difference between vented and non vented attics. It sounds like there is an improper mix of methods here. You want one or the other. In hot climates, moving the insulation to the perimeters of the structure and having the whole be conditioned or semi conditioned space yields the best results. https://www.buildingscience.com/documents/digests/bsd-102-understanding-attic-ventilation

Too lazy to read all the comments. There needs to be a fire barrier between a garage and other spaces of the house.

If you are in a humid environment you may need venting when going to the deck with fiberglass insulation but in a dry climate which I believe most of Arizona is you don’t.

Las Vegas/Clark county has been doing it for the thirty years we’ve been here in hundreds of thousands of residential and commercial buildings. Fiberglass wired tight up to sheathing with no ventilation over top.

If the Arizona residential code applies, here is the garage to dwelling separation requirement:

Even if there is no code requirement you should follow the IRC.