We need a to scale drawing before we can make suggestions.

You have a few options to look at to make this happen. Besides for getting a master bathroom, what else do you need in the house? Do you need 2 living rooms? Do you need 3 bedrooms? How large of a master bathroom do you want? It's easiest to install a bathrooms side by side, but not necessary. You just need to run plumbing lines to that location. Without seeing the full house, here is what I would suggest:

Turn the downstairs living room / bathroom into a master suite. You have plumbing downstairs already, and what sounds like a large space. You may be able to fit a good size bedroom (15'x13'), bathroom with 3, 4 or 5 fixtures, and a full walk in closet. That would leave your full upstairs as it is, and give you the privacy for a master on its own floor level.

You can look at turning bedroom 1 into a master bathroom. This would keep the master bedroom where it is, and give you a good size bathroom or a bathroom / closet combo. You can always add a small bedroom downstairs if you want to keep the bedroom count.

If you want to look at using your deck as an addition, I would suggest having the bedroom where the deck is, and converting bed 2 into a bathroom and master hallway to the bedroom. You can open up the living room on the patio side with a nice big door for an indoor - outdoor feel, and build a new deck there. I would be careful to examine if you are blocking light into the downstairs living room, and if there are local code requirements for this.

Hope this helps and gives you some ideas! Good luck with the planning.

Thank you so much for the response! I think the options seperating the bedrooms will be tough with two small kids that I did not mention.

Is there anyway to build a "galley bathroom" out towards the front of the house? We stayed in a hotel with this and it seemed plausible. It had a sliding door and was behind the headboard of bed. There is roughly 9 feet from front of house to walkway. Plumbing would obviously be a problem right? Is this idea even possible? This would avoid getting rid of deck and also seems like minimal disruption to life but I have zero experience. Thank you so much again for your help I really appreciate it.

I would recommend against building a bathroom along the walkway side, and it may not be plausible. You need to look into your local setbacks, and how close you can build to a property line. In California, typically its 5' in side yard, 20' to front and 15'-20' in rear. You are also required to have windows in each bedroom that count towards egress. From a usable standpoint, I think its awkward to be walking by a bathroom addition to your front door.

Perhaps adding an addition in the small yard area, for a bathroom that would be accessed from bedroom 2. Again, you may be able to add the bedroom itself there, and have bed 2 be the bathroom.

Thanks again Hambly Homes for your detailed response! My blueprint was so poor I'm not sure if it is possible to see the "walkway" is not a public walkway but just a walkway to the front door. The road itself is another 30-40 feet probably from the house. Still, it is probably not plausible as you mentioned. For some reason this route seems like it would disrupt the family the least and also be the most affordable although I'm not sure on either scenario.

For all the ideas you mentioned what do yo think a ballpark price would be in suburban NYC area. I'm sure these are pretty involved additions with a big pricetag? Any insight would be greatly appreciated?

Thank you yet again.