Figure out what you have into the property for total cost and than run a highest and best use analysis.This should tell you whether to rehab what is there or tear it down and build something new with the same asset class or a totally different asset class ( commercial, etc.).Additionally once you find out the highest and best use then look at the TIME required to develop that use and receive income from it or sell off.Some people will get the fire department to do a "controlled burn" on the property and use it as a fire exercise.

If you can't fathom how it could fail you'll walk right into failure.

Check with an attorney or the state MHA for additional guidance on that.

Always do the math analysis on a prospective property and try to look at it of at least have a clause in the sales contract that allows you some time (about 15 days) to make a detailed inspection and possibly walk out of the deal without a penalty that will hurt you too much.The thing you also should do in the beginning is to have a Team put together that typically have an Attorney, real estate Agents, a CPA (or accountants), Inspectors, general Contractors, and Handymen.  

There's a flipping book or two out there that walk you through repair costs... you can study those.  

@John ArendsenIn addition his debt to income ratio is not very good but there is plenty of equity.

Asbestos tiling in the basement...Part of me likes it, but the other part of me says holy crap don't walk run away!

Let me know if you need anything or have any additional questions.

Also, you can make a stronger offer if you are using cash.In my area, and given the units that I have been considering, this would result in about $100/m additional cash flow after debt service, and assuming 8% vacancy, conservative estimates for taxes and maintenance.

The first number that came up in my head was $15k and a new fence.If I can't subdivide I will keep house and add 1800 sq ft addition and house should be in $680k to 700k max.