No contractor is EVER your designer.

You have to help US to help you.

You need a drawing, accurate, every foot , inch. walls, windows, passages, every foot and inch. Where you would like to locate locate the new bath in the CURRENT condition.

You don't just plop a bath into a garage: ) and for all we know? You may be better off with an addition that does more, and you tear the garage off, rebuild that garage, depending lot lines and resources and a whole lot more.

Read up on fire codes for garages attached to houses so you can see why inserting a bathroom by punching a hole in the garage/house wall is not such a straightforward thing. Try googling something like

"fire codes to add a bathroom in garage Chicago" and use your own city, state or province in the search string.

Are you building a new garage, with a new driveway to it? Because that is the ONLY time a 200K project like this actually turns out appealing and gives you a net positive boost to the home value. Most projects like this just ruin the appeal of the home, and are done badly and cheaply. That results in a drop in value, plus the entire loss of the money spent.

Plan the scope better. Don’t involve robbing space from the garage unless you will build a new one. Get a good designer to brainstorm some space options with you, and go from there with planning. This is a lot of money to do right. It’s even more money if you do it wrong.

Thank you for the replies everyone. To clarify - we have a three car garage but only store one car in it so there is plenty of space, which is why we felt comfortable using up some of it for the proposed bathroom. It sounds like the unanimous recommendation is to get an architect on board first and go from there.

Agree with what has been said. This is going to be a 5 figure project, so to save time and money, I would do the project in this order

1- Contact the department in your area and get information of building codes and permits that you will need to do what you think is the job.

2-You should know how you water bill will change with the additional bath room.

3-The additional bath may change your home owners insurance or the rating of the governmental rating of the building

4- Obtain professional services to determine what can be done:

--The Weight bearing walls need to be identified.

--The location of all utilities need to be located including the availability of water, sewer, electricity in the area where you think the bath should go.

--Knowledge of the types of construction; ie it is one thing to go through a stud wall, and quite another to go through a poured concrete wall.

5- Working with a profession knowledgeable in construction, and electrical, sewer, and water codes, have them do an over all plan.

6- Ideally the above professional can sub contract all of the services needed, otherwise you will have to develop a list for each service and select the best for your job and budget.