prokyonid

First, pictures:

Interior wall

Ceiling & rafters

Exterior wall

Under the carpet

My 1962-built house in Ohio has this three-season sunroom in back that was converted from a covered rear patio. For the first few years I lived here, I tried to use it as year-round office space, but it stays too humid back there during the spring/summer/fall to not have A/C or a dehumidifier going at all times, and I can't effectively heat it during the winter, so for the last couple years it has just been used as non-climate-controlled storage. I want to change that this year and make it habitable year-round.

From what I can tell so far, looks like the existing walls are solid enough, so I think maybe I could just add insulation and drywall? I don't think those ceiling rafters are functional, looks like they're just hanging there, so was thinking maybe I could remove them and raise the floor off that concrete patio slab some too.

All advice is appreciated - I'm not an expert on any of this, though I do have some experience performing the actual labor that would be required once I know what I need to do.

I live in a 1960s-built single-story ranch in Ohio. The house was originally built with a covered back patio, floored with concrete. At some point, the original owners closed it up into a large sunroom.

The sunroom conversion was done extremely haphazardly - the exterior siding doesn't match, carpet was laid with no padding on the concrete, the hood in the kitchen vents into it, and the walls are uninsulated and undrywalled - wainscoting panels attached directly to studs. I don't know what the plan was, but at some point they must have been tired of it being so cold back there because they added a woodburning stove in the middle of the room (without properly screening off the chimney, so a few times a year a starling or a squirrel falls in and either breaks their neck or starves to death) and it must have too hot as they also ran wiring to install a large through-wall A/C unit.

I'm sure it's obvious from my description but the room is impractical to use as anything but storage at this point. In the winter, it gets colder in there than in my garage but I'm not about to run that woodstove and burn my house down, and in summer it's so leaky and humid from the poorly installed a/c unit and ancient single-pane sliding windows that every attempt to habitate it has resulted in having to clean blue mold off the walls and furniture in there. Thankfully the old patio door seals it all off pretty well, and that's what we've done for the last few years since we realized just how bad the situation in there was.

I'd like to make the space functional again, especially as it would increase my square footage by around 40%, but don't really know where to start.