The house was originally a duplex, but the city enforces a rule that a duplex that sits vacant for 12+ months in our zoning district, then it will be a non-conforming use and thus must be converted to single-family. 

The time lines are Strictly enforced. 

We are working with the closing's title company - they are reputable and we have an open line of communication with them, and the listing agent, seller's lawyer, and the reputable title company have told us it's clear there are no liens - to make sure we are sufficiently insured in the title insurance, to make sure the title policy has coverage without any of the liens exceptions listed on auction.com:"Most liens are removed after a foreclosure property sale, but certain liens may remain.Here are some examples:Any lien recorded on title prior in time to the foreclosing mortgage.First Mortgage (if the foreclosing mortgage is a second or third mortgage)HOA or COA assessment liens (in certain states)Mechanic’s Liens (in some states)Government liens such as state and federal tax liens, city or county liens, US Government liens.IRS liens (IRS may buy the property within 120 days after sale at the price paid at foreclosure sale)Code Enforcement Liens, Environmental Liens, and Utility LiensChild Support Liens"Is this the right approach for bank-owned?

They would have to provide proof that they did the work in order to have an enforceable lien. 

Call tax authorities, code enforcement and utility companies3.

If the answer is yes, then Opportunity Zones both enhance the potential for your own balance sheet, and allow you to redeploy capital from other investments.The two greatest unknowns that concern me are the duration of the investment for tax free gains, and future legislative changes that can dramatically alter the policy.

I think there may be Fairfax county rules against this, but I am wondering if anyone has an idea of how loosely/strictly those rules are enforced.

I was wondering if anyone had an idea of how strictly that ordinance is enforced as well.Thanks,Ben

I'm not following, do you have time to work on this place yourself, code enforcement aside?

Agreed...fresh start but let the resident know that the lease will be enforced going forward.My wife Anne is from Greenwood.