We are in the final stages of a multifamily project where our customer was rightly concerned about sound transmission, unit to unit. They asked that we investigate the use of Cellulose in the walls and floor/ceiling assemblies to reduce sound transmission, and for insulation. Cellulose isn’t exactly the new kid on the block. In fact, while researching, we determined that Thomas Jefferson’s Monticello was insulated with some form of Cellulose.
The Cellulose that we used was about 85% recycled paper with an R value similar to fiberglass batts or open cell form insulation. Beyond this, it also carried a Class 1 fire rating due to the incorporation of borates and ammonium sulfate, fire retardants in the product.
While we used the Cellulose in all walls and floor/ceiling assemblies, one has to remember that it is about 3x more dense than products of similar R value, and thus the weight had to be taken into account during structural design. Beyond the weight challenges, the good news is that, because of the massing, the cellulose it also has a tendency to reduce the lateral movement of the sheetrock.