It’s slightly more expensive, and most developers are trying to build the cheapest thing they can sell. A good number of places have put in noise separation into their building code though, so depending on where you live any new place will be dead quiet.
In a wood-frame building, for example, you increase the thickness of the unit-to-unit walls by a few inches and leave a small air-gap between two layers of insulation. The hard-soft-air-soft-hard boundary makes for a very difficult path for sound to travel through. You have to purpose-build the walls if you want maximum noise isolation, because the studs have to be staggered so they don’t bridge the gap and transmit the sound through your defenses.
It’s slightly more expensive, and most developers are trying to build the cheapest thing they can sell. A good number of places have put in noise separation into their building code though, so depending on where you live any new place will be dead quiet.
In a wood-frame building, for example, you increase the thickness of the unit-to-unit walls by a few inches and leave a small air-gap between two layers of insulation. The hard-soft-air-soft-hard boundary makes for a very difficult path for sound to travel through. You have to purpose-build the walls if you want maximum noise isolation, because the studs have to be staggered so they don’t bridge the gap and transmit the sound through your defenses.