Other items that you may need that will significantly drive up cost is if the existing size of the water meter and lateral lines has to be enlarge, the existing footing/foundation, lead removal for homes built before 1978, and other items.

You can get some great advice at these meet ups, plus it's great to be enlarging your circle.3. 

A permit application filed June 29 with the City of Austin and approved July 1 shows Austin-based Tesla plans to build a two-floor, 500,000-square-foot space to enlarge its General Assembly 2 and General Assembly 3 operations.

Less than a year after Tesla opened its factory just outside Austin, the maker of electric vehicles is already plotting an expansion.A permit application filed June 29 with the City of Austin and approved July 1 shows Austin-based Tesla plans to build a two-floor, 500,000-square-foot space to enlarge its General Assembly 2 and General Assembly 3 operations.

And you'll have new cracks in unexpected places, old cracks that will not close, but instead enlarge.

And you'll have new cracks in unexpected places, old cracks that will not close, but instead enlarge.

Trace the piece onto the wall, then enlarge the hold to fit the piece.  

I ran it through BP flip and wholesale, and it came in much higher than $128k, however I want to sell this quickly as it's my first one.Recent property same size 1600sqft just sold for $220k, and this property I'm selling is the same size and has a large spare office that can be converted to 1 or 2 bedrooms to add value, plus the kitchen isn't to big, which can be enlarged for cheap as the market doesn't require brand new kitchen cabinets.

the JADU must come from existing structure, but you can get around this by enlarging existing structure first, then add the JADU.  

I would give it to your GC and have him critique it and enlarge it as necessary.