Bump out from garage slab for plumbing

Alice Edwards
last year

Reaching out on this site for suggestions and thoughts on a project not started yet. Converting a detached approx 400 sq ft garage with slab. Have been granted a conditional use permit from city. This is not for rental but for Nanny suite, i guess it’s called. My discussion is for my curiosity as we have only just begun. Really don’t want to raise floor for plumbing, would have to raise complete platform so there would be no step up for bathroom only keeping every room level and really don’t want to break concrete or use upflush system. Was researching bump outs for bathrooms. Would a bump out for plumbing drain be doable? Our main house drain is approx. 20 ft from where the bathroom will be in the garage. If this is possible do i need to put all water lines on one wall? Using pex through attic bc have door placement in the way of some paths where i think lines would have to run to het to main out. Walls are 2x4, but was thinking 2x6 on bump out bc north wall and just may need it anyway for vent outs and such? As you can read, i’m not sure of this whole plumbing thing. I see how the toilet has to be raised and 4” down/out to main, but can’t understand all the other connections to that point. Was that clear as mud? If i used bump out for bathroom and dug into ground for toilet trap etc to main then poured cement foundation in bump out floor, then subfloor over all would this solve my issues? Just would like some discussion on my confusion. Any thoughts pros and cons are welcome. Have had several quotes on the plumbing from licensed plumbers but had not thought of this bump out idea until now. Please advise and thank you

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