Loan affected by adding unit to a quad?

[Frankie Lotrec]

Hello, please bear with me as I'm a relatively new investor. I have a quadplex it has a basement we roughed in to add a unit one day....well, we're thinking it's "one day".  My question is, since we may not need to borrow anything to finance this,
 will the mortgage payment be affected?  I have no idea how that works.....

thanks so much

[Matthew Drouin]

@Frankie Lotrec if you have an existing loan on the property and you plan to legally convert from a 4 unit to 5 unit , you should check the loan documents because you’d essentially be converting it to a commercial property, since 5+ units is considered commercial and subject to different appraisal approaches and so it would rule out the property being considered for purchasers utilizing residential financing.  This would be a significant modification to the underlying collateral and I’m sure it would be prohibited in your loan docs.