A smart landlord would certainly see this tenant as agitated (and likely to cause some grief) and offer a month's credit or something similar, a variation of the old "cash for keys" deal, and/or offer a few leads for relocation.That said, the lease certainly controls, unless for example white tenants who complain always seem to get a pass from the landlord and minorities do not...Fairfax County addresses the issue at http://www.fairfaxcounty.gov/consumer/tenant/tenan...    

Remember that even though the existing basement work is already complete (perhaps without a permit) you may have the architect evaluate the layout and show the changes in the drawings so the unit will be compliant.If its not part of the ADU pilot areas, your best bet is through a zoning change AND a zoning variation, for which you would need a zoning attorney AND an Architect. 

Might be some commonalities but still has many variations of difference.Good luck.

Cal. but the big guys are getting them but they have the cash to do so.I would look at finding a property that is not a major fixer but one that you can get with an FHA or Fannie mae rehab loan as an owner occupied. you can even get a co-signer.Look at my last post here:https://www.biggerpockets.com/forums/61/topics/732543-here-is-my-adu-variation-to-brrrr-its-called-bra2xrr

If you have a standard 25' x 125' lot (3,125 sq.ft.) you would be a bit short...2) If you are slightly under the required 3,750 sq.ft. and have some uniqueness to the lot, you may be able to obtain a Zoning Variation to reduce the required amount of lot area per unit in order to allow you to add the 3rd unit.

What I believe most people in my market have found is that in general it decreases the value of the property on average about 3%, with some areas being as high as 5% and as low as no variation in pricing.

There are lots of variations on how that plays out, including the option to use your initial etc in your profile, etc.

There are probably other variations on the depreciation method, but the easiest way I have found is dividing the improved value by 27.5.  

Adventures in CRE has a slew of variations of models available on a "pay what you can" structure.  

While there are some variations, almost all tree issues are the problem of "where it lands".