A structure including a first building unit; a second building unit; and a confined space between the building units. The units may be oriented horizontally or vertically. In an embodiment, the confined space is substantially filled with an organic containing material having a verified minimum installed density of greater than about ½ pound per cubic foot. In an embodiment, the confined space is substantially filled with an organic containing material comprising greater than about 20 percent organic material. Also in an embodiment, the structure comprises a structure connecting the confined space to the first unit and the second unit. The confined space provides improved fire, thermal and acoustic resistance properties.