What type of interview do you do with existing tenant(s) to ask them about maintenance issues?

Can your existing box support the addition?

I'm no appraiser but have plenty of fix and flips as well as new construction but IMO, it will be existing home. 

Thanks for all the advice, I'll definitely have to research more as I go about how to build out my portfolio and whether I want to pay down the existing loans or buy more.

The quaility of old existing units, and the ability of the long term population to pay new rents, blended with an influx of small high end mill conversion units is simply not balanced.

But a realtor will not know these underlying lots exist and for sure wholesalers wont have a clue.

we did that except instead of renovating it we knocked the existing home down and built a new primary. right after we were completed we had $500k in equity as we acted as the GC on the project. 

(I would not specify how much.)If the property needs a ton of repairs, then even buying it subject to the existing mortgage may not be enough to make this a viable deal.You need more info, and fast!

@Brett Jurgens  What is your current financing terms on the existing loan? 

The standing plan is to put in mini splits in each unit once the existing furnace finally dies.