I want to take out what is not taxable gain only. are you saying you lose the 250k exclusion on the 1031 because that 1031 may not stay as an investment property forever to make it sold. 

Here are 10 reasons for brokers to consider DSTsfor their clients.Avoid Leftover Taxable GainsFrequently, real estate investors encounter circumstances in which they identify a property in a 1031exchange that has a purchase price that is less than the proceeds from the sale of their previousproperty.

There are 2 basic rules to doing a 1031…-you must reinvest all of the cash received from the sale-you must buy a replacement property that is equal to, or greater, than the sales price of the sold property (less actual sales costs)Any short fall on either of these results in taxable gain in the amount of the shortfall, up to your actual gain and depreciation recapture….it’s not a “proration” based on how short you were.So in your case you were “$490k short”!

I'm guessing she has a $1,500,000 house free and clear, paid $200000 for it 40 years ago, some repairs over the years $140000 less the $250000 exclusion and $20000 sale expenses the taxable amount is a million dollars and maybe $400000 is owed to state and IRS if she sells while she is alive.Does she have a mortgage or credit card debt?

Many folks naturally load up over their life-time in the tax-deferred bucket and neglect the tax-free and taxable buckets.  

It's a balancing act, you want to do things right but you also don't need to do more than necessary but at the same time it's often easier, faster, and actually cheaper to just rip things out and start from scratch. 

The advantage of one property over several SFR is that the loan fees, insurance, taxes, water, etc should be cheaper pooled.

Private money will be cheaper typically, but if I am borrowing from someone inexperienced (like my cousin or uncle), that really has no clue about real estate, I lose that extra layer of protection.Andy

It will be much cheaper to fix than to demo and having it does add value.

Cheaper contractors tend to be more of a handyman, carpenter, drywall guy, or whatever not necessarily a GC.