Multifamily properties are allowed two detached ADUs and a third ADU, if possible, inside the existing structures.

First, do what you can to salvage/repair the existing windows before you consider buying new ones.

I am wondering if building log cabin is going to create more equity vs buying an existing log cabin?

@Robert Trevino Right now in my market the cost to build is just so much greater than the cost of purchasing existing that unless you’re building a personal home no one is building.

Hi Kevin, I'm well-versed in the pre-construction market but also do existing inventory, it just depends on what the buyers are looking for.

Buying subject to existing mortgage (AKA "sub2") - Find a motivated seller with a mortgage.

Maybe the best bet is a rental refi on one of the two existing properties to be able to get a new home all cash?

It must be an existing bldg that you are adding a unit too. 

Or maybe it already exists, Idk.

It is a situation where no lease exists, and you must comply with state and local law as specific to your locationIn my case I would give them a 30-day notice of rent increase and to sign a new lease.