@Lisa Foreman - I've used Crozier Environmental for properties in the Fredericksburg area and have been happy with them.

You might find great contractor who gives you good prices versus one who looks like great price but he will use shity materials.I have learned if you will try to BRRRR this that adding an extra bedroom and bathroom inside an existing footprint will bring extra value especially going from 1/1 to 2/2.

@Trevor Aydelott Huntington bank would not do it since I don’t live in their footprint state.

Here's the wrinkle -- the current unit is essentially built on the property line on three of the four sides, so demolishing it would meaning losing three feet on each side so that it follows city code - with a 600 sq ft footprint, I just don't think losing that kind of square footage makes the project feasible.

Individual structures are not the most economical or environmentally conscience method of housing.

(I think up to 1200 sf has to do with density and Environmental issues from the state for adding more people incrementally, this gets wonky...)You are allowed 700 sf max if you have a 6,000 sf lot. 

So it is possible and likely that 90% of 2-4 units you look at are in RS zones and considered "legal non-conforming"You are right, do alter it or increase density you need the alderman to change it to RT which will allow for 2-4 units and expansion.If you do not plan on altering the footprint you should not be concerned if it is RS

Building type - flat roof vs pitched roof, vinyl siding vs brick, sub grade units vs above gradeLocated in a flood zone or other environmental issuesOh, there is so much more...

I'm a BIG fan of Self Storage - either buying existing Facilities (and possibly expanding) or Development or Conversions of new Facilities.However, a 1/2 acre is going to be a small footprint that economies of scale may be somewhat difficult to kick in. 

Do a survey and environmental before you buy