Contact a local sole practitioner residential licensed architect. Many have a vast amount of varied experience that they use to meet your needs.

Déjà Vu

Do you have enough space to do all that without impinging too much on the neighbor?

Absolute costs will depend hugely on where you are located, so you might need to clue us in. But just breaking through an exterior wall and rebuilding so that it's integrated is nontrivial, so it could run into the six figures very quickly. Again, need location and probably an architectural consult to guess.

That's likely considered a tri-level rather than a true ranch.

A cautionary tale: I know of at least one family that added a two story addition to a true single story ranch (that had a cellar less than 8' high) as a DIY project and ended up not having sufficient head room for the stairs for anyone taller than 6' and adding the supports to cut the absolutely essential beam would have been another huge project not within their budget and changing what they'd added on that, other than the head room, they wanted to keep as is.

You really do need an architect for this project.

If a pro and projected costs are not in the budget, you might consider getting a price on doing the work in stages. If you create a large flat roof carport, the roof of which can double as a deck and would be strong enough to support an upstairs if/when added, perhaps you could build your additional rooms atop that later and/or enclose the carport to be a garage later.

Raised Ranch, not a Tri Level.

Is this what you are considering? Not sure how you will reach the new bedroom on the inside.

It's likely that none of your exterior materials will match the new addition so there may be additional costs to make things look proper.

This is exactly what I want! And yes, not sure how I would achieve adding another room without out reconfiguring the hallway and knocking down the bedroom walls. I wonder if it's ever been done before.

Find out from the market if you are creating a white elephant by adding just the garage to the side of the house. You can do this by contacting your Realtor to get an idea of how these type of additions work in the marketplace (take value away or add value). Even if you think you are going to be there "forever", the future is not known. I agree with the sentiment to find an architect so your home won't look like the 3rd bay was plopped onto the side.

A bit about cost vs value: I would be surprised if you managed to recoup anywhere close to 50% of the cost to add the 3rd bay. Potentially you stand to lose value entirely as in your home wouldn't get as much in a sales price as a home that looks more cohesive with only a 2-car garage. Every neighborhood is different. It's possible that your neighborhood sales wouldn't penalize your addition. Only way to know for sure is to look for similar sales. Know this before you make the addition. JMO

Ok thank you. I'll start doing a little research