If you don't mind someone urinating all over the toilet seat and polishing off your leftover pizza, renting a room is a great idea.

If a redesign into a 4-plex would be allowed, you also need to verify (also with Planning/Zoning or possibly Engineering) that you will not get slapped with massive IMPACT FEES for adding toilets, sinks and showers......and possibly electrical loads (from the monopolistic electric power provider).  

If this is the case I would sell it as your tax free profits are going to run out soon.If you can't sell it and receive this profit tax free I would only sell if you have a better investment in mind, otherwise just keep it and over time it will more than likely pan out to continue being a good investment. 

No Tenants, No Toilets!

We have run the calculator on this site to the point I don't even need to think to put in the numbers...but literally nothing has panned out.  5 cities, 600+ properties looked at, ~50 offers made using numbers that make sense (~10 at full asking) and literally nothing.  

The contractor really needs to know what he is doing when tiling a shower pan.

I have developed a wholesale partner program for beginners as well because too often they spend money on strategies that don't pan out.  

@Andrew Johnson mentioned water damage, but look at the top floor ceiling as well as the floors in all of the bathrooms around the tub and toilet.  

Round toilets bad, elongated toilets good. 

I may pay a bit more to own vice rent, but my counter-tops, flooring, toilets, door handles, etc. are all ones that I picked out and that (to me at least) more than makes up for the added cost of ownership.