They typically will get a piece of the action and get maybe 10% of the construction cost as part if not all of their fees.

I’m so new to this and trying to piece it all together.

I would caution against just finding piece of raw land near a road and throwing up a fence and shipping containers and calling it storage.

I just wanted to chip in a little piece of advice to help with this kind of search.

@David Brown, first you should make sure you understand the difference between money mortgage and contract for deed, as this are two distinct ways owner can finance your purchase. 1.

I've seen this type of layout before what was done when the kitchen needed to be remodeled was a small piece of counter (maybe a foot or less was added on the other side of the stove with a cookie sheet type cupboard underneath. 

One more piece of thought:Just because you can buy a house (1-4 units) for $0 down, doesn't necessarily mean you should. 

They can leave you at any time and you have to pick up the pieces.

The problem I foresee for you now is, if/when you take this to court, the judge is going to be presented with two very different and conflicting pieces of evidence (an invoice for $1,500 from you and a lawsuit for $18k from you for the same property/damages) and you're going to have to explain the discrepancy

For additional piece of mind you can reach out to an attorney for a small fee and they can set it up for you.