Blown cellulose and fiberglass create dust-sized particles, which can become airborne. Dust isn't a problem if it stays in the attic, but if it travels downward through the attic floor to the living space below, it can cause problems for homeowners. Insulation dust in the attic can enter the living space through penetrations in the attic, such as hatches, lights, diffusers, and grilles.
Dusting is a more significant problem with cellulose than with fiberglass. If cellulose is overly beaten during the manufacturing process, it will produce a lot of dust. Cellulose is fairly lightweight, so cellulose dust can easily become airborne. Fiberglass is typically cut into shreds, so it isn’t as dusty. Moreover, fiberglass particles are relatively heavy, so they tend to settle, rather than becoming airborne.
Dust in the home can cause health problems for homeowners. When dust stays in the air stream, it can be inhaled. Cellulose particles contain borates and other fire retardants, and some homeowners are sensitive to these chemicals. Dust can also cause maintenance problems. In the HVAC system, dust can settle on the louvers of the evaporator coil, effectively reducing the size of the louvers and increasing air speed through them. The faster moving air can blow water from the coil into the ductwork. Dust can also block air filters and settle on furniture, making the home feel gritty and dirty.
Unsealed penetrations in the attic floor allow air to transport dust from the attic to the living space below. Leaky ducts also transport dust from the attic to the living space. Dust enters leaky ducts in the attic, and the ducts carry the dust to supply registers, which transport the dust into the living space unfiltered.
Seal all attic ducts to prevent insulation dust from moving through the HVAC supply system to the living space. Also, seal all penetrations in the attic floor, such as lights, chases, and registers, to prevent air leaks into and out of the attic. Another solution, which prevents dusting altogether, is to stabilize blown insulation with a small amount of adhesive. The adhesive prevents dust particles in the insulation from becoming airborne. An alternative solution is to use batts or spray foam insulation, which don't produce dust.
