One apartment had everything needed, was unusually well maintained, a great location, very generous square footage, nice bathrooms, and plenty of natural light.

The % is based on the square footage of the office/square footage of entire house.

. 😄 I haven't even listed the new home yet because we want to do some work on it and I've already got people wanting to rent it (college kids and single people wanting roommate situation, they approached the seller and he gave them our contact info) - 1/2 the square footage and no upscale features, but it is a lovely historic home in downtown area.

The broker didn't inform me of the total square footage but the building is 3 stories high with the option of knocking down some walls to convert to 2 bedroom which to me sounds more appealing.

Many tiny houses are built on trailers with wheel and axles to avoid building codes and be considered a trailer which in many states would have a vehicle license.The gotcha however is that this still may not avoid/evade codes as many codes don't allow RV, trailers or mobile homes.It you go the other way and build a Tiny House without a trailer/wheels/axles, then you still have to comply with building codes which in many areas have minimum square footages. 

She's pulling solds that are a year old or that have square footage so far off the house I'm comparing them to, it has no value as an appraiser would never use them.From an 80/20 rule, if you want to calculate what your target house is worth, go on zillow and put in the address of your target house and then put in the following search criteria based on that target house.1) Square footage - plus or minus 250 square foot of your target house.So if your house is 1,500 sq ft, then put in a square footage range of 1,250 to 1750.

If you think there is a significant market with it as-is I would try that route.Is there any possibility of adding a bathroom with-in the square footage?  

Some areas have occupancy limits attached to square footage (or meters for you Edmonton folk). 

In addition, I found local ordinances that deal with minimum square footage required per person, per bedroom... so these vary from location to location.  

I typically drive the neighborhoods and call several FOR RENT signs to see what they offer (BR,BA, Square footage, utilities paid, etc) and see how it compares to what the seller is stating he gets.The other way is to ask for the current leases and verify that is what he has locked in.Finally, you could knock on the tenants doors and tell them you are considering buying the building and trying to verify what they pay for rent.