We are wondering now if we would do better to replace the garage
foundation, pour a new (one level!) slab and re-roof (and close up the
gaps at the beams). However, when I searched this forum, it looks
like the method often used is to jack the garage up completely and
then pour a new foundation. I don't think we can do this because of
all of the attached electrical and gas and water. I think our only
option would be to support one area at a time, tear out the old
foundation for that section and replace it. My husband is thinking
that he might be able to do this himself - we're not sure a contractor
would take on such a long drawn-out job.

I really appreciate anyone's thoughts on this.

NutMeg

I think you're focusing too much on the utilities. It's
a pain in the ass that they're run through the parts of
the property that you want to work on, but I doubt that
that's what's really driving the costs.