Is there a way to put a window screen there (or just staple some screen if you must)? Maybe someone at a hardware store could help.

I had casement windows in my old apartment in philly. There were screens on the windows.

I only open one side of the casement window in my apartment, and I use a chain to keep it from opening more than a crack (it wraps around the handle of the other window).

Works where I live, because it's often quite windy and 95% of the time you wouldn't want the windows completely open, anyhow.

We have the same situation. Luckily the previous tenants built their own and left them behind, but you can also buy adjustable window screens at hardware stores. The billion coats of old paint and uneven walls keep our screens wedged in place, but if you have nice square windows you could maybe velcro the corners or something if you are worried about the cat clawing at them.

I agree that lack of screens would concern me more than my cat going out there. Looks like a nice place for a cat to explore an get some sun!

We had a 3rd floor balcony apartment. I hired a handyman to build three 5'x5' wood-framed removable screens that rested on the balcony ledge (about waist high) to the "ceiling" (8 feet). That cost about $300 ten years ago. I'm willing to bet that for $100 you can get labor and materials for a removable framed screen.

Other DIY / CHEAP option:

Remove the wires from your baby gate with some heavy duty wire cutters. Paint the frame white or a color that works with your decor.

Edge two sheets of screening mesh (cut to fit your baby gate frames) with clear vinyl (you can do this with a sewing machine and a size 14 needle). I don't think you'll find vinyl bias tape, but it's possible.

Staple the bound edges of your screening mesh to the baby gate sections.

Random comment. If that flat roof is right outside your window, I'd see if the landlord would let you put a little area with potted plants in. You could make a little narrow screened in 'greenhouse' affair that the cats (and you) could enjoy.

What about building shutters into the casement, that would give you the fresh air and a nice light without having to put up screens.. something like this http://www.reliableshutter.com/colonial_folding_shutter.htm

For my casement windows, I cut 1 inch wide flat molding to size, used small nails and wood glue to create a frame, stapled some screen to the back side, and attached velcro to the corners of the screen and to the window frame. I just un-velcrow one side of the screen and swing it in when I want to open the window, and reattach. The whole project cost about $25 for four 54" x 24" windows and they work perfectly well.

When I lived in NYC, we had casement windows as well. The windows had screens that were affixed with brackets to the casement. The screens had a small sliding "square" so you could open the latch and the window. You can see a decent shot of the windows & screens here: http://flic.kr/p/9Wrp9n. Good luck!

I believe someone has already asked this:
http://www.apartmenttherapy.com/ny/good-questions/good-questions-a-screen-for-this-window-037283

how do you not have screens? my house would be filled with mosquitoes this time of year if I didn't

definitely use vinyl covered wire mesh. alone the wire might cut/hurt your pets. but vinyl covered will protect them. you can easily get a few yards at a hardware store for about $20.

i mounted a sturdy wide shelf w/brackets, and then used molding/furring strips as a box frame. then stapled the vinyl-covered mesh along the frame. my pet loves it, and spends hours in the sun!

Yes, omoriala is right. There was a similar Q & A recently on AT. Definitely check the link and also this one:

http://www.apartmenttherapy.com/ny/good-questions/ideas-to-help-protect-my-cat-from-open-window-situation-good-questions-131664

67 people commented so there's heaps of advice.

I think what you have looks pretty darn good, and is a good solution. Short of as someone above suggested, being able to build a contained garden where both you and kittles could enjoy together - which would be awesome!

I like this. I too live on the 4th floor, with 2 cats, with these same windows (should we start a club?) and almost didn't take the apt because of this. I ended up putting in adjustable screens, I have a frame that keeps them from popping out, and basically keep my windows shut when I'm not there. I live in SF so it's never hot enough to want to leave them open long, but it would be nice to always have fresh air flowing..

I've got screens on mine, like another commentor I can't even imagine no screens. I'd be eaten alive by mosquitos not to mention flies, birds and god knows what else would find its way in. But.. I think it depends on where you live, I'm in a tropical climate so no one is "screenless".

My casement windows are similar to yours. They all have screens on the inside.