You stated that the JADU can't be more than 50% of the primary residence which would put the JADU at 450sqft since the main property is just over 900Sqft.I think my main question is would I be able to go straight into a JADU add on that is attached to the main house with a max footprint of 450sqft?

You'll save way more money by buying a place that doesnt gave environmental issues.

So lots of big boxes have been reducing their footprints down lately.

Retail footprints for anchors are decreasing and the uses are changing, however, retail demand is super strong it's just in different sectors than we have seen in the past. 

Regional footprints apply, so if they want to do it in Alameda county, they have to have a physical branch in Alameda county, or Marin, and so on.

Any decent environmental consulting or engineering firm can knock one out pretty quick and inexpensively in most cases.

As for the shop, you’ll definitely need to have a phase 1 environmental study done as part of your due diligence.

I'm just using the basic parcel dimensions from various muni GIS files and Microsoft's awesome building footprint file https://github.com/Microsoft/U... for the building footprints on the parcels.

I imagine I need a team consisting of a good contractor and environmental engineer at the very least but any additional insight would be greatly appreciated.Thank you.

This unit has it all with high ceilings, large open modern footprint, and first floor master.