Duplex w possible illegal addon

[Robert H.]

Its a 1950 duplex under LA county authority I am considering putting an offer on with a small closet size addon that goes along where the sidewalk to the back would be. Im Pretty sure the main house has not been altered for it and it has been there for many years but is on the property line and now the empty lot next door is being developed so it most likely will become an issue. Whats the general range at how much this would cost if it needs to be removed?