In addition to ensuring that the room is built to the proper load bearing capacity as @Mike Reynolds mentioned, you should also keep in mind that you need a second egress point, such as an egress window, for any habitable room especially if it is designed for sleeping purposes.

I’ve run into a dispute with my property manager and am hoping to hear how others might handle this situation.The property manager just turned over a nicely updated apartment and in addition to the normal repairs and painting, installed new 2 inch blinds and ceiling fans in the apartment.

Additionally you want to model out a vacancy period at the end of each lease term, to be conservative. 6-12 month vacancy factor is common.

In high cost areas like SF Bay area where prices are higher than the replacement cost, square foot addition is a viable option for value add. 

I’m ready to start exploring my options to make my dreams come true.         

If you already have a property under contract or have a property in mind that you see as 60k all in you should build in 10-15% in additional costs as a contingency fund because things happen. 

In addition, I think there's more "control" with stocks in the sense that you can pull your money out whenever versus real estate, the money is not liquid. 

Right now, you are investing and aren't paying additional tax--think about that.Also, one little explained aspect is the carried over PAL is also useful to reduce your taxes when you goto sell. 

My vision involves a $200,000 duplex that not only offers a comfortable and affordable living space but also adheres to the principles of Pretty Good House, integrating the sustainable and efficient building practices advocated by Joe Lstiburek and Allison Bailes.Would love to hear more about your project and perhaps explore ways we can share insights.

I think you could leverage the equity to purchase additional real estate that may cash flow better, but it really comes down to what your goals are with investing.