Some of my rentals are grandfathered in, but are in areas where re-building would no longer be permitted. 

The first third gets eaten up rather quick , ordering materials , permits , dumpster , portable bathroom , etc .

I even reached out to hosts on Airbnb, and one said to call the city planner to get my STR permit. 

Hey @Tyran Melong,What is the open permit for exactly?

Did you obtain all necessary permits and licenses?

If I rent out three bedrooms at 600 each, that is double what I would be getting.However, it seems that renting out rooms separately isn't permitted unless you actively live there with the property as a primary residence (not sure on this point).

So, I’d dig into the numbers before making a call.Local zoning and code regulations: Converting a multi-family property to a single-family unit might require permits or specific approvals, so check with your local building authority to avoid surprises.

We'd need to pull permits to submeter the property, for example, and my understanding is it'd likely be denied due to not currently being to code.Has anyone ever dealt with this before?

@Eric Fichera Buy A/B  located properties, keep up with all local permitting & licensing, use a well drafted and fair lease, don’t unreasonably withhold deposits and be a responsive landlord or hire a responsive PM and you won’t have anything to worry about.

Engineering , permits , stormwater management system , clearing , reforestation fee , sediment control , and landscape bond , all this would run you around $175K .