I think it depends on whole bunch of factors including your relationship with your parents and where you live.

Best factor in the cost to build the property as a total loss at year 20.

It looks like they are taking cues from recent regulations implemented in Arlington, TX.That being said, the success of short-term rentals (STRs) boils down to fundamental factors such as location, pricing, and execution.

@John K.Your DTI definitely factors into things, but presuming you have rental income from your houses, that gets to be applied as a credit to offset that debt.  

Ryan offered various reasons for the delays, including difficulties in obtaining permits, scheduling subcontractors, and obtaining supplies; even making allowances for these factors, we found the delays to be extraordinary.While we were pleased with some of the subcontractors (e.g., the roofers, the fireplace repair crew, and the carpet installers), there were numerous instances when Bildwise and its subcontractors did not complete tasks in a workmanlike manner.

.”― Derek Sivers Reminds me of the "grit" factor https://www.youtube.com/watch?

This could be a significant factor in why housing prices are still so high.

Then the home was always used as a residence from time of purchase up until the last 2.5 years or so, which is NOT to be included as "non-qualified use", so the "Home" version should have 0 non-use days by the days owned, making my non-residence factor a big fat 0%, which multiplied by the gain makes my non-qualified use gain another big fat $0, meaning that my gain that is eligible for exlusion is 100%!!!!.......

If you're looking to buy value-add deals, a lot of investors I work with start doing BRRRRs with cash purchases and refinancing out so they don't have as many risk factors involved.If your market is seeing any kind of appreciation, I think it's smarter to leverage your money to get the bigger returns. 

Of course when the risk free rate is sub zero, those with capital are urged to deploy it (allow known as quantitative easing).Of course there are many other factors like operator experience, specific market, specific deal etc, but generally this is one of the largest factors.