Window restrictors - help !

[Vangough]

I am trying (without success so far) to find NON-screw window restrictors for UPVC windows...they open outwards with a handle that opens the lock (it has a key) The kids' room gets so stuffy but DS has just discovered sitting on the window sill so i don't want him to know how the window opens ! Ideally I don't want to drill holes into the plastic so any non-invasive solutions are welcome. Thanks..

Most PVCu systems use friction stays which can be adjusted to restrict movement - are yours just simple hinges?

Watching with interest

Hmm...no idea I am sending DH to investigate....

My windows were fitted with a hook and post type thing - very small. Fitted by Everest about twelve or thirteen years ago. Did the job. They do have to be screwed in though both to frame and underside of the window casement

pretty sure we have just standard hinges, no way of restricting how much you can open them...

Just found these window restrictors

Aww shame vangough, that would have been the easiest solution.

Sorry soremummy but those look as if they have to be screw fixed.

Have had a look through some trade websites but nothing yet, will ask a couple of window installation firms I use and let you know..