Hi, Ralph. The first thing is to check with and architect or structural engineer. You have to be sure that the frame will support a second floor and how you can tie it's load into the structure. There are a lot of things to consider and cutting frames for a dormer is certainly nothing to take lightly. They should be able to give you a "footprint" of where and how a loft can be added. Yes, there will be some cost in this but what would the cost of having something collapse be?