That depends on the breeds you are keeping. 6 feet is a breeze to fly over if you are a bantam chicken. If you are a large heavy breed, not so much.
You can trim one wing so that the bird has less control and ability to lift off the ground. Are these adults? The reason I ask is young chicks will molt a few times before they get their adult feathers and you would need to trim more often. Babies are lighter than adults as well and all breeds can soar over just about anything.
But if you want to trim the wings, trim only one wing, the primary wing feathers only. (the first 10 from the tip of the wing). Only trim to just below the primary coverts about a 1 inch. Here is a diagram of what I am talking about...
This trimming might keep them in place. You would have to repeat this process after each molt.
So glad you could join and enjoy BYC!