Consult a contractor for an estimate.
Raising garage roof height.
Approaches to raising the roof.
Raise the whole building or raise the roof.
But it is a big roof and expensive to do that for a small return.
There is only two ways to do that.
A truss framed roof on the other hand doesn t have any attic space to expand you re probably going to have to raise a truss framed roof to get more space.
And although almost any roof can be raised the cost of raising a very large or complex roof may outweigh the benefits.
In the first post it says he wants to raise the ceiling height of the garage.
You might also try raising the actual garage itself but this obviously has structural challenges.
Raising the roof and leaving the walls in place is a little easier but the task of disconnecting the roof from the walls is more difficult than disconnecting the walls from the floor.
You could brace the inside of your garage and use hydraulic lifts to raise the roof.
Hence i wish to raise the roof by say 9 to 12 inches.