Warming outside room

I have a room in my house which is used to be a covered deck but now it is enclosed. Every wall is exposed to outside, the room has 4 windows one one wall, one window on wall with a wall AC unit (never has been used), and one wall with window and door. The last side opens up to the inside of my home where it used to have sliding glass doors to the covered deck. The problem is that during the cold season it is constantly cold and not habitable. Cold air just comes in the home form the large opening. I put in some weather striping around the door but that did not solve it as the entire room radiates cold form all directions. I do not know how to solve it other than tear down the drywall put in insulation everywhere. This does not solve the cold coming through the floor which also is exposed to the exterior. Can anyone advise as to the best solution I can take? Please detail as best as you can because I am really interested in ending this once and for all. Thank you very much.

 

Things aren't warmer just because you add insulation. If there is no source of heat out there, it's no wonder it's cold! You have two options. 1... Add a source of heat, like an electric heater and prepare yourself for the fact that it's going to have to run 24/7 to keep it reasonably warm in there... or 2... tear the floor, ceiling and walls off so that you can properly insulate and air seal the thing (which was not built to be living space in the first place) and THEN put the electric heater in there and expect it to still run most of the time.

You have 5 surfaces losing heat... 3 walls, floor and ceiling. Windows are horrible... R-2 if your lucky, and they are probably drafty... and so is your window AC. They let in a ton of cold air which is why people take them out in the fall!

That's why they call rooms like that "3 season rooms". They aren't habitable in winter. They ought to call them 2 1/2 season rooms. Because half the summer they are also too stuffy and hot.

Florida rooms work in Florida, not where we have cold winters.

 

Thank you for your advice. As you said not to use that room often at all...I was thinking of just putting in sliding doors to the room and seal it as best as I can then call it a day.