[David]

I added 22 feet to the back of my 2 car garage for about $12,000. Now it's 22 x 43 feet. I paid $5 a sq ft for someone to do the foundation and then built the rest myself. This included $1400 for moving and upgrading (to 200 amp) my breaker box. I also added a sink and more electrical circuits. I think it was cheaper than starting completely over, but I don't know if the same would hold true going from 1 car to 2 car.