This inquiry may seem redundant, based on a recent thread about a garage needing a "ceiling", or self-evident, but I need specific advice. While I routinely call for drywall/firewalls to be installed on the wall between an attached garage and a dwelling, we see so few basements here in Oregon-- and fewer basement garages-- I've yet to encounter the following set-up. The subject: Single level 1950s Rambler measuring approximately 24' x 50'. Due to its mildly sloping parcel, three of the sides are bermed/ground level, with the north side cut away with retaining walls to accommodate a 24' x 29' basement under approximately 3/5 of the dwelling. The basement is entirely open with no partitions. Walls are poured concrete, and ceiling is open wood joists and exposed wood-plank subfloor of the first level floor. The basement is accessed via a typical interior stairway from the main level, and via a 9' wide basement wall opening which is covered by a horizontally sliding "garage" door. The assessor's records correctly cite the basement area as 667sf, and reference the "Basement garage" as 230 sf (of the 667sf). This would assign it a theoretical 10' width by the 23' depth, despite the lack of partition walls. My experience and gut tell me that there must be drywall installed on the ceiling, and possibly a dividing firewall with fire-rated door enclosing the garage portion. I expect that the parties involved in the sale are going to object when informed of that, because there is so much heat ducting and exposed plumbing/wiring/mechanical in the ceiling that drywall installation will be complicated, so I will likely need authoritative references. I read an old thread which described a similar scenario, wherein the OP proposed a second option of walling in the vehicle opening and reducing the access to a "man-door", which is a cheaper option, and negates the need for the extensive drywall. Contributors to that thread berated the OP for over-stepping his role, but my experience is that the agents/sellers/buyers in these situations want the appraiser to call for the cheapest, fastest fix so the property can qualify and close escrow. In this case, because the existing garage door is a barn-type wooden sliding door, replacing it is probably the simplest, cheapest option. I can't see any way to avoid calling for the firewall if the large opening remains, allowing someone to park a vehicle inside, based on fire and carbon-monoxide issues. To complicate matters, although the dwelling is heated by electric baseboard units in each room, there is an old wood-burning furnace in the basement, with ducting to all rooms-- even rarer in these parts! Although it likely has not been used in decades, it looks fully connected/functional. Gratitude in advance for authoritative info and informed opinions.