@Randy D for revenue industry standard is charging a flat fee (see chart below) or a consistent percentage of the monthly rent(8-10%). 

In terms of legitimate numbers, besides the construction cost above, remember that the majority of these homes are very old and adding rooms can be tedious, stressful, and might make you want to pull your hair out!

Also, be sure to have multiple car dash cams, and ring cameras in every room.Don't ever go in the same room alone, never close the front door or any door in the house, never look her in eye, for goodness sake never make any comments about her clothers, hair, appearance......depending on what specific things listed above, you think are a joke or good common sense, will determine your level of neuroticism about the topic and should probably let you know if you have right mind set for the leasing agent job...jus sayin

I know its splitting hairs and probably wont matter, so I'm just wondering.Thank youJohn

Currently the first floor is a hair salon and the second floor is a one bedroom apartment.

Look at this chart.

Who knows they may be able to work something out with you and elevate the situation a hair.

Eric probably took the average or mean for the entire state in his comparison chart. 

Don't split hairs with words.

Pretty interesting, though it'll take a ton of time to customize the chart of accounts the way I'd need them.Looks like it integrates with Salesforce, but only invoices (through Breadwinner), right?