I agree, it would be a good thing to call in a contractor or two and get some quotes. Not only for yourself, but, also for resale, sometime, maybe in the future.

Can you post a picture of the basement wall that abuts the garage and where you would place the connecting door? Where do gas, sewage, and water lines run in your house? What is in the space underneath your porch? What is your foundation made of? Do you ever had water issues in your basement, run off issues from the hillside?

@kendrah it actually appears the two arent exactly at the same grade, but are indeed butted together. The original house foundation is stone, about 20" thick at a higher grade then the detached garage. The detached garage wall is roughly 8" inches thick. There is a copper water line and some electrical conduit that run out to the garage from the basement. As you can see from the photos (first 3), the conduit and copper exit into the garage near the ceiling, but the photo from the basement (next 2) shows those pipes existing in the lower 1/3 of the basement, so clearly the basement is a bit higher elevation. This may require some stairs/landing of some sort i imagine. space underneath the portch is free. No sewage or gas pipes in the way here. No water issues in the basement have been observed.

This is not going to be a big deal for the right team.

thanks for the input!

@Hallett, I concur that the work itself won't be a huge deal. Do you think there is any merit to the OP consulting a structural engineer? Or do you say just hack away?

I do think that plan has merit but only you can decide if it is worth the cost . I think this is something you need to have conversations with contractors who have some experience working with masonary in a situation like this but I think most of the work will be inside the garage .

" Do you think there is any merit to the OP consulting a structural engineer? Or do you say just hack away? "

Oh no, you definitely need to get an engineer involved here as well as building permits. You want this completely above board. Last think you do is just start hacking away. Good way to have the house fall on top of you.

Yes i agree with that haha! Will have to dig through 8 inches of garage and 20 inches of foundation for a door (possibly with stairs given the slight elevation)...so above board is the only way to go in my opinion. Probably a bit expensive, but i wont know that until i get quotes