How easy is it to move a garage and attach it to a house?
Moving a garage is not very difficult. Here are a few pointers:
(1) In most cases, you will have to add some temporary structure to keep the garage from falling apart while it is being moved. For example, you might have to "tie" the walls together to prevent them from spreading out.
(2) You may be able to skid the garage on the ground by lifting the existing wall plates onto some wooden skids and then pulling the garage to the new location. The pulling can be performed by a vehicle or a "come-a-long" (a very useful tool in all types of construction).
You might even be able to lift the garage onto a set of pipes, or a set of wheeled dollies and roll the structure into place. Whatever you do, don't use your back!
(3) Don't assume that the garage or the house is square. You will most likely have to fill in some of the space between the two structures.
A note about zoning and building codes: check with your local zoning and building departments and find out how local codes apply to this job. In some areas, detached garages can be near a property line and houses require a larger setback.
You will likely have to create a "20 minute fire wall" between the garage and the house. For example, you might have to add a layer of 5/8 drywall to that area and a solid core self-closing door. - George