Better talk to a plumber about where the bath needs to be in relation to the sewer/septic line. It's not as simple as you think. Here, auxiliary buildings need their own connection to the main, or their own septic. They can't share the home's main. There's a whole host of regulations covering that, that are local. You need someone local who understands those to navigate that for you.

You need real dimensions indicated. I think the stairs are gonna eat up a lot more space than you think.

Looks good. But I hope you've checked whether a coach house is permitted under your zoning regulations.

We can tie into the existing septic, no issue there. The detached garage will be permitted per zoning, so no issue there. How much room will the stairs take up do you imagine?

Your sketch and inspiration pic show a dormer that isn't the full width of the garage - but your bathroom is in the corner. I think the bathroom needs to have full ceiling height.

Do you have to have a shower there?

How high is the first floor ceiling? Ours was high enough that the stairs required a 90 degree turn. I'm guessing yours won't be, but it's something to consider.

Also, what roof pitch do you want?

I think you can't afford to NOT get an architect involved.

AnnKH, the inspiration pic doesn't show but ours will have full ceiling height everywhere upstairs from the way my builder described it with two dormers and the peaks connect to give plenty of headroom. I want a shower because down the line, it may be a place to stay for friends and family.

Lolauren, bottom will be 9 feet- how high were yours?

Mark, thanks for your opinion! We shall see how it goes. But I am very doubtful of needing one after building our entire house without one. I am just trying to work through the placement of things.

Here is another drawing I did, I gave up on the bad software and made it in photoshop. If the front wall is 25 feet and we have a 16 foot door, is that enough room to have a staircase on the side like that? We could make it 26 feet if need be

Or this one.

Just waving hi Fiona. Definitely remember your build and your photography skills - and your sweet girls. Good luck!

You will NOT be able to float a bathroom over a garage door. Just physically impossible for the plumbing. It's going to have to go at the far end of the stairs, where you can run the pipes down into a storage area below.

You need a 20' door if you actually plan to park two vehicles side by side and one is anything other than a compact. 25' isn't really big enough for a real world two car garage with that unusable bumpout and the enclosed stairway that you need. You need at least 32'. Or make it a single car garage only. Or do exterior stairs.

Sophie, ok good to know! It will be so helpful for me to know these things meeting with the builder next. The biggest struggle is making the stairs and the bathroom work WHILE saving the walls where the best natural light is. I need those walls for big windows. If I put the bathroom in the corner where the stairs come up, I will be taking away a great light corner. Do I have any other configuring options?

Autumn.4 HELLO! So nice to see a familiar face :)

The garage will mostly be used as a gym. We are not big car people and my parents have a 16 foot garage and both of our cars (an older 4runner and Subaru) fit just fine. The reason I am worried about exterior stairs is because we have a lot of rain here near Seattle and I worried about the upkeep and them being slippery.

You just need to make sure you can use a wall to run the plumbing, which you could do with some jogs. Make sure there is enough slope and may need a bulkhead to do it, but since it is by the garage door and it is lower right there anyways it could work. Also need to make sure it is well insulated as you don't want the water lines to freeze.

We had a similar space in a home we owned. The left and right walls are mot going to have as much headroom as you think. I would also worry about resale - you say you aren't garage people but I think you will still want a functional garage, even if you don't use it.