It can be done, just be sure your walls are tied together so they don't spread, or make sure the ridge is supported. If the roof is trussed then the answer is no. Other things to consider is insulating the ceiling/rafters and where are the heat and air ducts going to go if they aren't in the floor. You will need to rewire also.
New members: Please consider adding your location to your profile.
If you do what you've always done, you'll get what you've always got.