I have a detached garage that I want to expand or rebuild to create a shop space. The garage was built before we bought the house, and I don't know anything about the existing concrete slab (foundation?), other than it seems to be in relatively good shape. The garage was probably built in the last 15 to 20 years and was done by one of the "garage builder" companies common in the Chicago area. Definitely not high end, but I hope it was up to code.
Is it feasible to expand the footprint of an existing concrete slab, or do I need to remove and replace? If I were to dig down around the existing edges, what could I look for to tell if it is good enough to keep? If it is suitable to use and expand, how much more difficult would it be to add to two sides of the existing slab rather than just one? I am planning to hire someone to do the concrete work and I'm sure they will have opinions on these questions, but I want to understand what I will be facing so I can do some preliminary planning and design.
Thanks for any help you can offer.