One of the reasons Retrofoam works so well, is it fills even the smallest voids within your walls perfectly. Encompassing every pipe, wire nail and screw, creating perfect positives to even the smallest areas within the walls of your home. This perfect fill, leaves no space for rodents or bugs. RetroFoam is naturally resistant to mold growth and contains neither cellulose nor other fiber that sustain mold growth. RetroFoam has high nitrogen content which is toxic to most molds, but which is otherwise non-toxic and inert to humans. Empty walls act as conduits for air transfer through walls, channels that often travel from attic to basement and every possible outlet in-between. As air works its way through your walls and into your living space, it will carry dust, molds, fibers from other insulation, particles of pest dander and droppings. Besides all the other obvious benefits, Retrofoam puts a stopper on all these air passages, preventing the possibility of contaminating your living spaces. The video below illustrates how Retrofoam works to stop even a pressurized air flow in comparison to Fiberglass and Cellulose.