My girls I am having issues with them jumping up on top of a 5 1/2 foot roof and now on the fence. I am ticked to say the least!! A ROOF FOR SURE! Free ranging is another question in itself. Do you have predators? How old are the flock? Do they know where home is to come back at night and walk in and go up the ramp to the sleeper? If not no free ranging!
My chickens have fencing because they wander off my property. No roof because they have places to get away from hawks (bushes, roofed front porch, etc).
My mom's chickens were just attacked by a neighbor's dog that got loose and went straight for them, so no more free ranging there either. My mom now uses 5' 2x4 wire fencing that doesn't have a "roof" because there are plenty of places to hide if a hawk shows up.
The run is sometimes to keep the chickens safe rather than to keep them contained. Make sure your arrangement is dog-proof and hawk-proof (or that your chickens are smart enough to hide). Even big cities have hawks and coyotes, and unleashed dogs can and do kill chickens.
No, you do not need a run. However, a run does provide some safety for your chickens. If you're not concerned about possible losses, a secure coop at night should be sufficient for a free-range flock. If you do build a run, know that a run without a roof is as good as no run when it comes to protection from predators. They will either fly or climb in. I don't clip my birds' wings, so someone else will have to chime in.
When I first got chickens I built a run with a wire mesh roof and kept them in for the first year but as the flock expanded (and it inevitably does), I started to let them free range. They stay within a few hundred feet from the coop and put themselves to bed at dusk. I have lost one chicken to a predator (skunk) in 3 years. It depends on how you feel about losses. Personally, I don't mind a few losses for the lifestyle it allows them. I've had to keep them confined to the coop and run for 2 weeks at one point to see if they were laying eggs elsewhere (they weren't) and felt sorry for them becasue they were confined. I think it's a personal decision.
We have a run under our coop (about 4 x 20) but not one hen goes in there except to get some feed or water. They free range in the yard all day - we have a 6 foot privacy fence and a large tree line. They never leave the yard - even the one who flies 12 feet off the ground to roost in a tree every night (we go fetch her and stick her in the coop). However, we will be fencing them in (with a roof) this spring because they managed to get over 8 foot screening we surrounded our terraced garden beds with and destroyed most of our crops this year. They'll still have plenty of roaming room (over 200 s/f for 6 hens) but we want to grow veggies this year and actually be able to harvest them!
We started out letting our chickens totally free range in our backyard. However, we just closed them into a large fenced in run area because they were stripping my veggie garden bare and pooping all over our deck. In order to make the space suitable for all our uses, we decided we needed the run. Also, they were flying over our 6 foot fence into our neighbor's yards and causing problems there (either with their dogs and cats or laying eggs all over). So we went with the run with a partial roof. The partial roof covers areas where they can get up on the roof of the coop or our shed and get out. Hope that helps! Good luck!