> Walls that are paper thin with no insulation so you can listen in on your neighbor's phone calls. These sound like wild assumptions with nothing to back them

> Walls that are paper thin with no insulation so you can listen in on your neighbor's phone calls. These sound like wild assumptions with nothing to back them up. https://basc.pnnl.gov/code-compliance/air-sealing-and-insulating-common-walls-party-walls-multi-family-buildings-code https://basc.pnnl.gov/code-compliance/air-sealing-and-insula... "Many builders are insulating these walls fully for sound proofing purposes per the International Building Code (IBC), Section 1207, Sound Transmission walls, partitions, and floor/ceiling assemblies separating dwelling units from each other must have a sound transmission class (STC) of not less than 50 for airborne noise when tested in accordance with ASTM E 90." Also the comment I replied to said 'americans' not 'in america'