Ditto the last 2 posts. I've seen several converted decks done without inspection or adequate thought that has very insufficient foundations. Deck foundations aren't designed to carry a house load and often not even an added roof Egress codes can't be overlooked- they are an instant code-fail, but sometimes (based on the layout) you can add a window that meets egress requirements to the original bedroom and make things work.
Like converted carports, enclosing a deck can work well sometimes while other times is doesn't, but rarely is as simple a matter as it looks like to the inexperienced eye. There's a lot more to things than a single glance and a thought tells you!