My next door neighbors had a great screen house on the side of their house in Houlton Maine. I loved that house and the screen house allowed them to live outside from the beginning of May, right through September, with just light jackets at the beginning and the end.
Later on when I lived in the Bath-Brunswick area of Maine, my ex-wife and I became good friends of an older woman (probably about my age now) in a town near Popham beach. She used her screen house most of the year, as the screens were basically light weight storm windows with both glass and screens on two sides.
Strangely, she did the room on the north-west (inside) corner of the house, but she was still able to use it some days in the winter.
I will go over....in not too much detail, how both screened rooms were done.
The first hurdle to get over in a true screen house is that if you are bringing the walls of the screen house right down to the floor, be it concrete or wood, you are going to trap water along the inside perimeter of the screens. Rain will fall at an angle or be blown into the space through the screen and in trying to escape, or puddling up inside, moisture will collect against the joint between the walls and the floor, and cause rot. Unless you are doing something like aluminum frames for the screen and concrete or some other impervious material for the floor, there will be deterioration.
The one solution that I have seen in the past is to lift the screen off the floor somehow. Putting blocks under the frame for the screens will mean that only the blocks will need regular maintenance, instead of the entire screen frame. However, this also means that there will be a gap in your bug protection. You will need to cover that gap with screen. Perhaps only a narrow strip, stapled or glued to the bottom rail of the screen , and grazing the floor will do the trick.
Likewise, if a floor is made of dimensional lumber of some kind, there will be gaps between the boards, and screen will have to be used here, under the floor.
If you have framed your porch like a normal wall, and installed screened windows, there will inevitably wind blown water entering the room and puddling against the baseboards. Again. some provision needs to be made to keep water from settling there and rotting. Perhaps a panel or the baseboards can be removable inside and out, to be sealed up in the winter when the windows are closed. Presumably, this is not a heated space, so loss of R value will not be an issue from lack of insulation in that space. It would be a big chore to stuff insulation in a space like that in the fall and remove it in the spring.
I will do this over the next few days.