How do we ensure guests not climbing out windows onto roof safely?

[Laurie-and-Scott2]

We recently renovated a 100 year old home and are welcoming our first guests this weekend.  As we were taking our 20 something kids through it this weekend they immediately said that people will be climbing out our 2nd story windows to smoke on the roof.  Of course, we never considered this as a concern.  We asked our handyman to secure the windows and he indicated that for safety and egress you have to have them open fully.  Any suggestions to ensure that guests don't climb out onto the roof?

[Lorna170]

@Laurie-and-Scott2   There is a roofing product that buildings install to deter birds — a set of wire and spikes.   This could be implemented just outside the windows and would still allow for egress by humans in the event of fire, but would be a visual deterrent to roof-climbing smokers.