Example - borrower uses loan to purchase a home in a B or C grade neighborhood for 380k, spends 50k rehabbing primary home, uses 200k to put an ADU in the back, appraisal comes back at 925k. 

Purchase price: $350,000 Cash invested: $10,000 Sale price: $435,000 Primary residence converted to a rental after 2 years.

I do this as there is so many different ways persons choose to do such, so many different fee structures, so I keep it off and I tell clients UP FRONT to keep that in mind and add what is specific to there situation.   

. :)This is especially true if you rely on furnishedfinder.com as your primary lead source (which you shouldn't, but that's another post) as when you make that connection with a prospective resident, you are selling yourself as a landlord as much as you are the property as a place to live.

We sold our (primary) home recently.

There is a big difference between the 2.

If you feel ambitious, you could try a BRRR strategy adding additional equity to the subject home and then taking equity out of it to pay off either the HELOC or if you decided to the refinance the primary residence. 

It is an investment property, and does not meet the qualifications of being her/their primary. 

Income taxes- if needed can you use your 2 year primary residence deduction if a taxable event occurs.13.  1031-  if any part of the insurance claim is a taxable event is there some way to do a 1031 with lenient time frame adjustments?  

You should have a good idea of every expense you have in your primary home, then add the STR specific:  (These are rough estimate numbers, depending on various factors)STR insurance - a special insurance that covers both the property and your liability, could be $2~4k in areas without natural disasters, could be more than $10k in some other areas.cleaning fee - approx. $50 per bedroom, so a 4-bedroom house will cost you about $150~200consumables - bathroom supplies, kitchen supplies, beverage supplies: $20~30 per week, depending on how much you providewear and tear - towels, linen, kitchen utensils, some furniture: $1000~2000 per yearRepairs/replacement for things that guests break or steal:  $1000~2000 per yearAlso, if your personal use is less than 14 days a year, the entire property's expense is deductible against STR income, but if you use more than 14 days, then you will have to calculate the proportion of how many days it's rented out vs how many days you or your family uses.