Tomorrow  .............12 square of shingles .    

For example, within my area do I want to be in the ball park of the comps for dollar per square foot?

I know that I should look at square footage, bedrooms, and bathrooms, within a .5mile -1 mile radius.

First sf is square foot.Second, let's say you do all your figgering and guesstimates on a faux cap rate. 

I'm considering buying a house in DC that's roughly 1000 square feet, but 400 of those are unpermitted.  

I need a forced hot air furnace for a well insulated 900 square ft row home in the kennsington area of philly

Adding additional square footage to a flip is a time consuming and costly option best left to someone with construction experience.

If you owned a few square blocks and it was close to town?

I am looking at a property that I would like to build a fourplex on, and am trying to figure out if it is actually viable or not. the construction doesn't bother me so much as I am do construction for my living, I am trying to get an accurate cost per square foot.

Now they do look at countries with no tax returns, money laundering, and criminal activity as red flags and they avoid those.So you have some options.