I charge my clients for the hours I actually work if I'm working from home which I do most of the time.
One of my clients has a really annoying habit of arranging calls/work and then deferring for an hour, then half an hour, then another. So I can't do anything else - because it's not enough time to really get anything else done (other than putting on a load of washing or something). Or sometimes they want me at the end of a phone/email in case there's something they need me to do.
Would you charge them for the hanging around time?