I have lived in my 1960s terraced house for three years now and based on what I can hear from nextdoor (steps on stairs, doors slamming, people’s voice when shouting) I have always assumed we had single brick party walls.
In the loft you can clearly see a single brick wall pattern with no bricks placed at 90 degrees to tie into another wall.
However, having recently cut a hole in an external wall (but very close to the party wall) to fit a rectangular duct, I realise there is indeed a cavity between the houses, I could put my hand in there.
What strikes me is that if there is a cavity, sound insulation should be much better than what it is as the houses are basically decoupled/detached
What could be the reason?
In the loft you can clearly see a single brick wall pattern with no bricks placed at 90 degrees to tie into another wall.
However, having recently cut a hole in an external wall (but very close to the party wall) to fit a rectangular duct, I realise there is indeed a cavity between the houses, I could put my hand in there.
What strikes me is that if there is a cavity, sound insulation should be much better than what it is as the houses are basically decoupled/detached
What could be the reason?