Why aren't more semi detached houses built with the front doors, hallways and landings adjoining? Surely this way there would be less noise between houses? I am looking at rightmove and all the new builds around here have hallways and landings running along outer walls and main living rooms and bedroom joined to next door. Why not build to mitigate as much noise as possible? Why not have 2 walls between main living and next door? I've wondered this a few times over the years!