Evaluating House Price

[William DaSilva]

Hello,

I am hoping that some of you folks can enlighten me in this situation. I am putting a house in the market. The property is a single-family with the permit to be converted into a two-family. I am wondering what would be the criteria you would use, if any, to calculate the value of this permit opportunity in order to define the property sale price. 

In order words, I am able to find out what a single-family would comp at, however, I am not sure about what is the extra value that the approved permit will add to the property. 

Thank you in advance.