Let's start with licensed home inspectors: in what state do you live?

https://www.spectora.com/r/home-inspector-license-requirements-map/

Licensing of home inspectors is not required in my state.

Okay...what about the seller's disclosure?

https://www.nolo.com/legal-encyclopedia/state-state-seller-disclosure-requirements

It would be difficult to answer this question without knowing your location, as you have b5 and MI in your name I am going to assume Michigan.

Before I even start realize that your recovery would be limited to the damages from the fraudulent disclosure, so it is likely just the cost if the cold air return.

In my quick research, Michigan seems to be a pretty tough state to act on disclosure issues. You must prove the intent to defraud even though the form has an "unknown" box. I am not licensed in MI. so don't take my quick search into cases as gospel, but I would consider the trouble vs payout before pursuing this.

But -- what is recourse for no permit for work that should have been permitted? Like -- an entire ADDITION not being permitted? HVAC?

Are you sure the work was unpermited? That's a lot of work to have been done without anyone noticing..

There is no legal recourse. It sounds like you're the second owner since the work was done. Why didn't you check that permits were pulled assuming it was obvious it was an addition? It's likely the seller didn't do so either for the same reason.

Inspectors are licensed in my state.

"But -- what is recourse for no permit for work that should have been permitted? Like -- an entire ADDITION not being permitted? HVAC?"

Permits are just odd. Permits essentially stay with the home and don't move with the owner. So you could report your suspicion to your local code authority and they can then require that you, as the present owner, get permits and bring the house up to present code. Once you have spent the (probably) considerable amount to accomplish that, you can then look for other people to recover that amount from... Recovery can be difficult if not impossible if significant time has passed.

In reality, you likely have no good recourse.

"So you could report your suspicion to your local code authority and they can then require that you, as the present owner, get permits and bring the house up to present code."

Yea, that's something I'm afraid of...

The electrical work is in the process of being brought up to code, there's a laundry list of issues the electrician is working through, and the HVAC system will be done correctly and permitted, since a whole new system is going in. I'm just so bleepin' tired of turning around and finding something else that was not done as it should have been -- like I said, I love my house but dang if someone knocked on my door and named my price I'd sell and start over, the amount of money I've sunk into this place on necessary (non-cosmetic) issues in just 5 years is ridiculous.

And if my state would pass licensure for home inspectors, all this would have (or should have) been discovered and I at least could have negotiated down the selling price. Like $50-75K negotiated. Yah....

"if my state would pass licensure for home inspectors, all this would have (or should have) been discovered and I at least could have negotiated down the selling price."

In my experience licensing doesn't change a whole lot. Our state has licensing requirements and the quality of an inspection here seems to be a crapshoot.

Most homeowners don't even know that permits are required for some things. An HVAC replacement? I'm guessing about 5% of homeowners would know that a permit is required (in some states or municipalities) for that.

I get the distinct feeling the owner previous to the guy I bought the house from didn't pull permits.

If I understand correctly, the owner who owned the house previous to the last owner added a 625 foot addition and did not apply for any permits. If permits were applied for, then the code official of your municipality should have these permits on file. Be aware you can apply for a permit, to the work, but then never call to arrange for a final inspection.

In many cases people add additions and then extend the supply duct to the addition. Many HVAC systems are over sized, so supply heating and cooling to additional conditioned space can be done. I am not sure if the code requires a return to be installed in a new addition. This is something the code official can answer for your situation. Bad installed furnaces are a major compliant on the HVAC forum. This is not unusual. If this is an old house, I can image the amount of bad electrical wiring done or the years. If the house inspector didn't flag anything, then he should be in another line of work.

Do I have any recourse here if, in fact, permits for the addition and the furnace were not pulled?

This is something you need to discuss with your real estate attorney. Every state and municipality has rules as to what needs to be disclosed at the time of sale. The sales contract may also have language to cover situations after the sale.

I agree with mike_home, you need to speak to a real estate lawyer. Otherwise ignore a lot of the misinformation others have stated above

In my state, the mandatory disclosure rules for residential real estate transactions includes a question along the lines of "was any work performed of a nature requiring a building permit, for which no permit was obtained?". All entries in the disclosure are, of course, caveated with being what the seller knows or believes to be true. Undisclosed, unpermitted work generally needs to be remediated at the seller's cost. It could be similar or different where you are, that's why you need to talk to a lawyer.

I think people put too much faith in house inspectors. Homes are sold as is, without warranties other than implied functionality and good repair of components as one would expect to find and use in a home. And excluding any disclosed exceptions. What you see and what you don't see is what you get. A home inspector does little more than kick tires. Home inspectors are not HVAC experts and they can do little more than turn it on, sense the function, check for leaks and holes. You can imagine even if your home inspector were a qualified and experienced general contractor, they still would be lacking HVAC expertise.

Good luck