Not sure if that would change your recommendations, but it's another variable in the decision. 

A heloc is interest only so lower payments and none when not using the money but typically it is  line of credit commitment for a 10 year period before changing to an amortized loan and the interest rate is variable (during the non amortization period).

It depends on a few variables.

Apparently grandma lost her house in the financial crisis - well that was 10 years ago, and people only generally lost their houses if they had mortgages on them that changed in amount (i.e. variable, balloon, etc), and supposedly grannie has been at the same job for 15 years.

@Marisa Faulkner This is going to depend on a few key variables that will be different for many of us depending on where you are in the US.

In other investment realms such as corporate finance or stocks, people often use a probabilistic approach where each variable has a range of outcomes that vary along some distribution (i.e. normal/bell curve, triangular, etc).

I think they know that there are so many variables with construction that the contingency will cover any of those variables and they will hit the profit target.

@Albert Liao - The variability of them, not really knowing exactly what they are going to be from a month to month basis.

@Evelyn Tilman there is a lot of loose variables as a flipper that would make or break a deal. 

There are a lot of variables (as ini everything), but it should only take a 2-5 years to earn it back after getting my pilot's license.