No need to start a new thread! Papa Bear gave you some good advice.
If you'll allow it - I'll hijack my own thread and question the logic to add a bathroom. Your numbers suggest you're in a LCOL area where upgrades should be very carefully considered especially if they aren't DIY. If you DIY it and use mostly low cost or salvaged materials then putting a few thousand into it is kind of a no brainer, but if your intended space isn't adjacent to an existing plumbing stack and you have to hire a plumber or electrician then it can easily become an investment that doesn't pay off for a decade.
I'm guessing you could rent it out for ~1200 currently and you envision getting an extra 120 or so with another bathroom?
Thank you for being a willing participant in your own hijacking JBoogie! Interesting. I would like you to convince me. It would be much easier to NOT do it and yet I feel compelled. Here are my reasons:
1. Quality of life. It is a 1700 sqft apartment with two levels. It is a bummer getting out of bed and going downstairs to use the bathroom. So from a pure livability/laziness standpoint an upstairs bathroom would be an improvement. But if I am honest, it is unlikely I will be living here 18-24 months from now.
2. Desirable Tenants. This is a 3-4 bedroom place (plus a very small bedroom that I'm aiming at for 2nd bath). I think 3-4 friends are more likely to share a place with two bathrooms.
3. The place feels like it is SUPPOSED to have another bathroom. This actually worries me. I may find that there is something about the property's configuration or structure that makes it prohibitively expensive to add one.
as for expected rent differential... I think it is more like $350/m, 1300ish vs 1700ish.
My comps are: next door neighbors pay 1600/m for smaller 3br/2BA.
My downstairs tenant happily pays $1050/m for a two bedroom/1BA. He thinks we could get 1200/m for his spot, but I don't raise rent on tenants who cook us delicious things, watch our cat when we are out of town, and enjoy a porch beer with us now and again.
I am in a LCOL rustbelt city - but it is trending upward. Hard to tell what will happen long term but this neighborhood is desirable for walkability, proximity to downtown, entertainments.
I am DIY curious, but adding a bathroom is probably not the right project to get my feet wet on. I'd hire this out. The bedroom is located above the bathroom downstairs but the footprints don't coincide perfectly. I need to get a pro in to investigate feasibility.
Thanks for pushing me to think this through. Does getting a 350 return instead of 120 change your mind at all?
-RLT