Are you looking for operable windows or fixed glass? If operable, it may be best to reframe the wall and provide proper support for new windows and door. If fixed, I suppose you may be able to install new insulated glass in the existing openings, if they'll take the weight and there's room for stops. You'll need to meet energy code, so will have to insulate ceiling and whatever portion of wall is not windows.

Your wood framing will likely need to be redone. It isnt "strong" enough to hold a regular window. Thats the easiest way to put it. Also if the floor is a concrete slab there are specific steps that need to be taken in order to tile it or else the tile will crack. You can't just put tile on concrete. If you want to keep it as a porch but close it in which would be your most cost effective venture and would not need permits etc. You may want to look into EZ-Breeze window system. This will keep dirt and pollen out but also will enable you to still open them up on days where you might want to enjoy it as a porch.

I'm surprised about the reframing suggestions. Those are 4x4 vertical supports that support the roof. You really think the fixed glass would be too heavy? The back part of the room is brick. Heres a few more pics....

They are not "deep" enough for a window. They are not 4' deep.

So sorry, I don't understand. Each one of those vertical posts on the screen portion is a 4"x4" post. So you say they are not deep enough? I don't get it. Thanks!

Some windows will fit in that space. You can always shim out either direction.

Thanks for that but I definitely want glass.

In most jurisdictions you will need a permit because you are adding conditioned space. You will most likely also need a structural engineer.

Your patio slab and footings were designed to hold a certain amount of weight. You want to add a lot more weight with tile and windows.

You also want to air condition a space that was likely not designed for that. Is the roof insulated, for example?

I have 4"×4" posts, front and back porches. Originally screened in, previous owner replaced screens with inexpensive vinyl sliding windows. Porch is covered by existing roof, has slanted plank floor over pier and beam. I'm planning on fully converting those porches to livable space, so I need to reframe most of the structure, add sill plates, level joists, build out walls 16" on center, etc. Most of the costs to convert would have been the foundation and roof, but since those are already done, and to code, I'm looking at mostly materials and a couple days of labor for framing. We will add sweat equity to finish interior. I haven't priced out windows yet, so those will be biggest cost, I think. Porches are 8 x 28. I ran electrical wiring already.

So, long post but main issue for you *might* be foundation and roof. If those are up to code, then look at potential framing issues to support roof, insulation, etc.

You’re saying there are solid 4” x 4” posts between each of the screens, for a total of six, correct? What about the corner posts? And the bottom plates—what are they made of? Are they sitting directly on the foundation or are they sitting on brick veneer? And how is the roof framed?

Yes, a total of 9 4x4 posts including corner the posts that sit on row of bricks and poured concrete below the brick - just like the slab. They trimmed the outer portion of the slab with brick. The cross members are 2x4's with a 1x1 inch nailer attached to them. The posts have this nailer too. Its for the screen currently there. The screen is sandwiched between these nailers. Not sure how that part of the roof is framed. It comes off our main roof. The house itself is 4000 sg/ft.