Adding Bathroom to Upstairs house

[Colton S.]

Hey BP,

We are looking at a 4 bed / 1 bath house with 1977 sq ft. It's a two story with the bathroom on the first floor and 3 bedrooms on the second. I'm considering adding a second bathroom above the first one and doing most/all of the work myself. I don't have the house yet, just speculating what it would need IF we purchased it. I have experience with tiling, plumbing, framing, etc. My estimate for the cost of this bathroom is roughly 3-5k just because we wouldn't have to hire out.

My question is, what problems do you foresee this creating? How simple/hard is it to tie into existing plumbing? Is there anything I should look out for