There are projected returns but no one guarantees a return.

Thank you for the linkPeople mistakenly think just because someone is interviewed on a podcast that they are heavily vetted or it somehow guarantees they are trusted.

Even worse, if your "about 4.5%" interest rate proves to be not conservative enough.Extrapolating your idea, if you did this every time you moved, you'd always still be looking at negative cash flow while they were being built, and likely while you were living there.I worry that somewhere along the way, you'll be taken advantage of by your building contractor/s, who might start seeing you as an endless source of guaranteed dollars.People tend to not be as careful with their money as they should be, if too readily available. 

It's generally easier to go from short term rentals to longer term ones but it's not a guarantee.

@Ari BachrachCouple additional points to add to my colleagues' excellent answers.The 15% savings that  @Ashish Acharya mentioned are not guaranteed.

Being that an FHA  loan is a government guaranteed loan, only available to Investors who are househacking, it offers a lower down payment and an optional seller assistance. 

And for a mere $50,000 most real estate attorneys will give it a shot with no guarantee of the outcome.Do not assume the investor said he was an attorney until you speak with the investor and see the paperwork.

They have different levels of window with a lifetime guarantee.

Limited Liability on you personally: If you were sued (a tenant is injured on your property) or had a legal case against you as a landlord, it would be against the corporation and not you personally so it can assist in protecting your personal assets in this type of situationThe title of the property will be in a corporate name but you, the investor, will be required as the owners of the corporation to also provide personal guarantees.

@Imthiaz AhmedYou might want to talk to your lender if it's too late to put the property in the name of the LLC with you personally guaranteeing the loan.