We have a home in Walnut Creek California (east of SF) that was part of an old walnut estate. When the land was subdivided, our lot got the 20'x40' tractor barn - probably built in the 1930s. The person who built our house added a double garage door onto the barn, then used it as his workshop to build the rest of the house. So there is a ranch style house, with a barn perpindicular to it, and set back about 8 feet from the front edge of the house.
Here lies the problem. The barn/garage has a very minimal foundation that is barely above or at ground level. The interior slab was poured in two sections, and there is about a 2" height difference between the "car" area and the "workshop" area. The slab is cracked, the car section has some cracks that are now up to 3" wide and deep. The roof is metal and starting to leak (the rubber washers on the roofing nails have deteriorated). And because this was originally a barn, the roof beams extend out and the roof rests on them - so every wall has a 6" gap at the top. Nothing is weatherproof - tools rust if left out, we only store things in plastic bins these days. The wall structure is okay, my husband did a good amount of termite repair when we moved in. The mudsills on top of the foundation show some damage and I'm sure there is more damage hiding since the foundation is so low.
We thought that it was time to bite the bullet and tear down the garage and attach a garage to the house. However, because the barn was the first structure on the property, all of the electrical, gas, and phone are routed to the garage at one end of the barn, then routed to the house. At the other end, all of the gas, electrical and water for the pool are mounted on the back wall.
In talking to contractors, it looks like the cost to demo everything, relocate all electrical etc, grade the area next to the house where the attached garage would go, and build the garage on is going to cost a lot more than we had hoped. We had also planned to add about 5 feet to the house in order to add a closet to a room at that end. The only other costly change is to add a shower to the 1/2 bath. The cost estimates for all of this are looking like a minumum of $150K. A lot of the cost is due to infrastructure, there is really a minor amount of electrical and plumbing added.
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.