Code violations?

I don't know what the process would be like to turn an existing structure into a boarding house--but I'd imagine, your larger problem would be with existing zoning, which likely would not permit a boarding/rooming house in a zone where you currently have a single family home.The state maintains information about rooming and boarding houses here: https://www.state.nj.us/dca/divisions/codes/offices/roomingboarding.html but your municipality will have its own zoning laws about what is permissible.

so when a new property comes on the market i can look up the zip and address and know 1) have i ever reviewed this property before and if so what has changed, 2) i have detailed comps for the zip code.  

However, I do feel that as an aspiring real estate investor, it would be remiss of me not to take advantage of the benefits provided by the tax code.

Somewhere between $20/sf and $250/sf, depending on:- Specific scope of work- Type of contractors- Level of finish- Type of house- Time of year- Your negotiating skill- Local codes/requirements- Size of houseIf it's a big house, there's no major mechanical work, you want vinyl flooring and Home Depot level finishes, you're probably in the $20-50/sf range. 

(Raphael had the street numbers and zip code wrong.) 

I know that old houses were not always built up to modern code.

MD Code, Business Occupations & Professions, § 17-601.  

Link to the code: https://www.law.cornell.edu/uscode/text/26/1400Z-2Code Language:IRC Sect. 1400-2(c) In the case of any investment held by the taxpayer for at least 10 years and with respect to which the taxpayer makes an election under this clause, the basis of such property shall be equal to the fair market value of such investment on the date that the investment is sold or exchanged.This often confuses people and they think that any investment qualifies for the 10-year exclusion.

Just be as professional as possible,  know your local codes and laws about moving out a tenant.