Architect, which is easiest way to get the permits, ~$10k.  

Can anyone recommend a good architect that can tell what it would take to legalize it? 

We had to move out tenant, they had to hire an architect, get plans and go through the whole process.

Those types of buyers usually need longer timeframes to do soils, environmental, deal with planning/building dept/public works, etc, not to meeting survey, engineer, architect, etc.

Building a coachhouse in the back is roughly $200k minimum from the architects that I have spoken with. 

I have one at 45 but he can do all the work for me -- from architects to subs to project turnover-- and has built a 80ksf strip mall, too bad he is only on call, since his price is steep, but he is there if i need him.

As an architect and now investor that lived in Ontario, this kind of well designed renovation project ticks all the right boxes

Hey @Mario Morales - I've had some experiences legalizing basement/garden units in Chicago.If you are planning on trying to legalize it as an additional unit or ADU I would recommend first connecting with an architect if you haven't already because there could be other issues that don't allow you to legalize it like ceiling height, light & vent, etc.If that's the case I would just rent it out as is and not worry about the 2nd door...as I am sure you know it's pretty standard in Chicago to rent out non-conforming garden units.

Here are my favorites: True Built ADU's start at $139/sq ft but you're completely on your own for permits, site planning etc. https://truebuilthome.com/home-plans/adu-homes/Greenpods range from $180-$300/sq ft http://www.greenpoddevelopment.comStillwater homes are fancier and range from $350-$400 but their price also includes a project manager, architect etc. http://stillwaterdwellings.com

I am an architect in NYC and have seen it all, they can make or break any flip/deal as far as I am concerned.