This sounds like a mad question, I realise, but I have no personal experience.
We are having a two floor extension built, then once the windows are in they will knock two single size doorways into the house (one on each floor). DH thinks the dust/mess will be minimal, it will only take a day and we won't even need to empty the rooms that are being knocked through to.
My impression was that it was going to be awful with masonry chunks/dust everywhere and we at a minimum need to clear the two rooms that are being knocked into and possibly tape up doors from that room to the lounge to minimise spread of dust.
Anyone with experience of knocking through a doorway into a room want to shed some light on what level of mess I should be preparing for?