I love my enclosed patios, but beware of the people hired to install them. The salesman will promise you anything in order to get the sale, but the construction crew may not be able to deliver those promises. We had a 10/12 4 season patio installed on a second floor flat roof. The Building Inspector must have been paid off, because he OK'd the design. 25K later, we had a room after weeks of delay. Unfortunately, 2 years later it started leaking onto the first floor. We also were invaded by moisture-loving ants. 2 more years go by, and we had to tear off the entire roofing system. It was nothing but styrofoam panels with 4 floor joists. BY this time, the water poured in whenever it rained. So please take the time to get an independent building inspector who is not being paid off to find out if you can do what the sales people tall you you can, for sure.
By the way, the tear off came to 10K, so we are still paying for a room that has not withstood the promises made. Custom Patio went out of business in our area, but still does business in other States, so be careful.