We have French doors that lead to a study. I’m not sure that you can tell from the picture, but the handles are “dummy” handles. They don’t move. There is no mechanism to them. I would like to be able to secure this room. My biggest issue is that my cats can push hard enough against the door to open them. The have something at the top of each door that is supposed to keep them closed (not sure what they’re called) but they don’t hold well enough to keep the cats out.
Slide bolt?
Nars, I really can’t tell what I’m looking at in that photo. Obviously I can see the handles, but nothing else makes sense. I have no clue to the actual size of the doors. How about a photo that shows the entire door set, with a perspective of wall/floor/ceiling.
How about one of those things like on hotel doors. It’s a clip like thing. Not sure what it’s called. Takes the place of a chain slider lock.
The hardware that you currently have at the head to keep the doors closed are called ball catches. They’re just spring-loaded balls/rollers that keep the doors from drifting open in the wind. They could potentially be adjusted or replaced with ones that are stronger, but the harder they are to open, the harder they are close as well. A simple bungee cord or some sort of clasp that clamps between the two existing levers would also be enough to keep the cats out.
Surface bolts (what K2500’s photo shows) would be the easiest to install. If it’s just to keep out the kitties, then one on each door at the top would be enough. Putting them on the bottom would mean drilling into the floor. One thing to consider, this provides no way to unlock the door from the outside in an emergency. That’s a minor consideration, but something to keep in mind.
Replacing the levers with ones that are functional, basically with buried multi-point locks or internal (flush) bolts would require mortising out part of the door to install. Surface mounted cremone bolts are basically surface bolts with a lever, but they’re the full height of the door and everything is exposed. Not sure that’s the aesthetic you’re looking for, and it’s probably overkill. Those do allow for functional levers on the opposite side of the door as well, depending on features.
Here ya go. Ignore all the junk. I call it a study because that’s what I want it to be. It’s currently a junk room.
Don’t use bungee cords - it would risk badly injuring your cats, especially if they’re already used to being able to push the doors open. (I’m envisioning a cat pushing the doors open, starting through, and the bungee cord closing the doors on their middle.)
Right now, I’m using rope. It looks as ugly as you’d think.
Unfortunately, the doors open into the room.
Don’t you just need some form of metal rod, bent at both ends, that you simply drop over the handles?
Or maybe a long shackle padlock.
Those are some good looking doors. I love the paneled framing. That said, the handles aren’t level with each other and I’d just have to get that fixed for my own sanity no matter the cost 
The doors to our bedroom are similar: glass paneled French doors. One of the doors has a bolt built into the door that slides into the top that keeps it secure. The other door just has a working lever that latches into the other door.
If you want it to be a study and want to keep the cats out that implies you’ll be opening and closing this door pretty frequently. If that’s true, I’d recommend installing a setup like we have. We pretty much keep the one door bolted shut all the time and open and close the other just like the equivalent of a regular door that latches into the jam. I think you’ll find unbolting and bolting surface bolts at the top every time to be a mild annoyance. Likewise with any jury rigged “padlock” type solution. Just turn it into the equivalent of a regular door for your day to day opening and closing use.
One of our external doors is similar, except the one door has surface bolts into both the top and the floor. That seems necessary for an external door where you want to lock it more securely. I’d prefer it if our bedroom door was similar just because the bolted door would seem more securely in place. But it’s good enough, certain enough to prevent drilling into the floor, etc. from being worth it.
We have the same mechanism on one of our French doors too and we had them get loose over the years too.
Here’s what I did :
The ball in our case fit a 1/2 inch pvc pipe perfectly. I cut a 1/4 inch piece of pvc pipe and sanded it nicely to make a sleeve. Next I inserted the sleeve on the top of the door and then put the ball in it (it just raised the ball by 1/4 inch).
Has been working fine for 2 years or so.
Quick, easy, attractive, cheap.
ETA: a $3 hook and eye would work as well.
Just realized that my post wasn’t clear. On the top of each of the doors, there is a groove.
A metal ball sits in this groove and ideally rubs/seals with a plate attached to the top of the frame.
You have to raise this ball a little bit. For me 1/4 inch was enough, but you may need to do more. It will be obvious to you once you use a ladder and see the upper edge of the door.
A simple hook latch will do. To really lock it you need upper and lower slide bolts on one door to immobilize it, and them use a conventional latching mechanism, but for an indoor room that’s more than most people would need or bother with.
I was thinking the same thing.
I never noticed the uneven handles until I took the picture. I think the problem is that the doors aren’t level. They rub (slightly) on top.
Those are good looking doors. And if your cats are anything like my cat, they won’t abide with a locked door and will scratch the living hell out of them trying to get in.
Your best bet is to keep a large predator in the study, say a coyote, bobcat, or maybe even a wolf. After a few encounters, the cats will reduce their forays into the study.
If you really want to be flash you could remount the doors on some railings so they slide open. But you might also have to do some adjustments to the frame on the inside of the study.