This actually would be a vacation home for us. I didn't want to bore anyone with all the details, but perhaps it is relevant after all since you brought it up! There is a loft which will provide sleeping space, and other all purpose space. The main floor currently has 3 beds and 1 TINY bath, and we'd like to make it 2 and 2. There is a full walkout basement with another bath and bedroom and additional living space. So at the end of the day it would be a 3 bedrooms, 3 bathrooms and a loft.

If it is too costly to turn one of the bedrooms into a bathroom we'll look into stealing space from one of the bedrooms and expanding the current bathroom.

Thanks for your reply! Any thoughts, now that I've added more info?

Ah, I think 3&3 for a vacation home would probably sell as well as 4&2. Bear in mind, I'm not a real estate agent, so I could be wrong.

So, you have a full basement where they can run plumbing. So that works in your favor, as opposed to being over a crawl space or on a slab. Within reason, you can probably add a full bath where it makes the most sense for the floor plan of the home. I mean, don't put it at the far opposite end of the house from all the other plumbing but they don't have to be back to back.

Here's what we did when we replaced our second floor: we drew up a few floor plans and narrowed it down to 2. We got advice from our GC on what would be easier (less expensive) to implement. He seemed to appreciate being asked for input and I think it helped him understand we were looking for an ally/advocate in the building process ... Not just someone to hammer wood together ;)

Thanks for the reply. Did you use an architect?

No, I did a lot of the layout myself (I have a copy of Visio) and then we used a draftsman to do the final plans (including the roof plan, insulation, electrical, etc).

With liberal use of Houzz website and driving around to see what we wanted to mimic and avoid, we didn't feel we needed an architect to get the proportions very very close to ideal. We are very happy with the result, so I think we made the right call. If you can put in the hours then you may be able to avoid it as well :)

I've never heard of Houzz and I've just spent the past half hour drooling on that site! Thanks for the heads up. That's great!!!

Susan, if you're still looking for encouragement, we turned a 4br/1ba second floor into a 3br/2ba. The new master bath used to be a bedroom. My husband did most of the work himself and wasn't nearly as expensive as we thought it would be. We were able to frame a 4 inch bump out in the room directly below the new bathroom which accommodated all the new plumbing, and then ran it through the floor into the basement. It turned out great! Good luck.

Also find out if the house uses city sewage or if it has a septic tank.
Adding another bath could mean upgrading the septic.

If it was me yes, I would do it.

We also are looking into turning a 4th 10x10 bedroom into a bathroom. However, we are not DIYers. We are seniors and are wondering what it would cost to have someone do this project. We have never hired people to do our renovations as we come from a large family and someone was always offering to help with the projects. Our family is up in age now so we need to get a pro which is scarey. We have no idea what a project like this would cost us. The bedroom shares a wall with our current small bathroom. We are on town sewage. Could someone help with some info? Thanks.

30-60K depending on location and material choices. Assuming you don't go crazy with material choices and structural alterations to try to do a curbless shower.

Yikes! Didn't think it would cost that much. Someone else said that 15K would be the high end depending on what we chose. We will be getting 3 estimates so I guess we will find out soon what the cost will be. Thanks for the comment Sophie.

Just the materials for DIY would easily run 15K. Read the current thread about Bathroom Remodel Budgets and Cost vs Value. You don't even have any infrastructure in place for a ''remodel''. You need all of the plumbing and electrical from scratch. Beware lowball estimates from unlicensed and uninsured contractor with no waterproofing systems specified and box store materials.