Yeah, great idea, but after pricing just a "remodel" of a master bath that already had all those things in place, I'm going to say that you're not going to like the bids and the amount of work involved in this plan. You'll get by cheaper and easier building a new bathroom space most likely. There is a ton of work, foundation breakup, plumbing, and all that involved with what you're wanting to do. I wouldn't purchase the home at all if it needs this much work to be usable. Forget the HGTV renovation budgets or whatever you've seen about remodeling, because a project of this magnitude can easily skyrocket in costs. Those TV remodel budgets generally aren't anywhere close to realistic.

Cost will depend on where you live and the materials you select. In Sacramento, we gutted an existing small bathroom to the studs because we suspected water damage. Moved tub and sink but not toilet (no vent stack or roof changes). Changed a window. 3 custom cabinets (vanity, between the studs cabinet, over the w/c). Very modest materials and finishes. $18k. We think we got a screaming good deal.

We were quoted $50K in Dallas, Texas, for a master bath add-on from one of the most expensive contractors in town. Everyone else said we could get it done for half that, but that was with all plumbing already in place and just extending the shower area. I think we ended up with a bill around $15K doing minor plumbing modifications and lots of new tile and waterproofing work with the Schluter system. We thought we got a good deal with that, too.

Why isn’t anyone addressing the step down into this room. I can’t imagine getting up in the middle of the night and having to step down into a bathroom.

I think you can find something better.

I suspect that this room is an enclosed porch or add-on, with a step Down like that.

The difficult parts of this conversion would be the connection to the existing sewer system, and then dealing with the step down (get rid of it!). If the sewer connection cannot be made at a reasonable price, I would not consider the conversion.

They have that washer draining somehow, but it might not be code compliant, and they also had more flexibility with the height and slope of a washer standpipe. The standard design drain for a commode must be at floor level, 3" diameter, and must have the proper slope to the main sewer pipe. Its not that hard to demo part of the slab to make the sewer connection, but sometimes the existing sewer pipe run is not running in the right direction to make it flow properly.

Bruce