cellulose, fiberglass and rockwool Fiber Insulation

Sprayed fiber insulation is mainly an alternative to fiberglass, cellulose and rockwool batts in wall insulation. Properly applied – by fully filling the wall cavities, without gaps and voids – this type of insulation creates a uniform layer that reduces air circulation within the cavities and, consequently, higher levels of energy-efficiency.

Fiberglass, Rockwool and cellulose Fiber Insulation vs. blown insulation

Fiberglass and rockwool fiber insulation is used in a wet mixture that involves a solution of glue and water. Only cellulose fibers do not require the glue...

Though the insulation fibers are dry at start, they become wet when mixed with the glue and the water in the blower equipment.

That wet mixture binds the insulation fibers closely, allowing an excellent adherence to the cavities and a better insulation value than simple blown insulation.

Sprayed Fibers and uses

Sprayed insulation involves fiberglass, mineral wool (rockwool and slagwool) and cellulose fibers, and shouldn't be left exposed. They aren’t abrasion-resistant...

Only fibers with special treatments (higher amounts of adhesive binder) can be left exposed (these special fibers have also an increased acoustical performance, and are applied directly in most surfaces).

Fiberglass and Mineral wool vs cellulose insulation Fibers

Mineral wool and fiberglass fibers require glue, while cellulose fiber insulation has its own adhesive.

Cellulose has a slightly higher insulation value (R-value), but it far less resistant to fire or to insects. Cellulose fiber insulation demands adequate fire-retardants and insecticide treatments.

Cellulose insulation fibers also demands special cares with moisture (contrary to mineral wool or fiberglass). Cellulose insulation is too prone to water problems, and should only by used whenever it can be kept dry.

equipment

The installation of fiber insulation requires adequate equipment. Fibers are fed dry into the machine, before traveling to the hose and nozzle to be mixed to the adhesive and the water, and that can't be done without a proper blower.

Drying times

The insulation fibers should be allowed to dry adequately in the cavity. Only then they can be covered, without compromising the whole installation.

Drying times vary with ambient conditions, the amount of moisture, and also with the thickness of the insulation and the width of the cavity. Under typical conditions, since fiberglass and rockwool don’t absorb water, they dry out quickly, often in a day. But cellulose will require more time, often two days.

Persistent humid conditions will demand larger drying times and can compromise a safe covering.

Installation demands

Though relatively straightforward, fiber insulation isn’t easy to accomplish properly without adequate know-how. And, as alluded before, it requires proper equipment. The mixture should fill the cavities completely and uniformly.

Manufacturer guidelines, concerning density, moisture content or vapor barriers (often do not recommended) should be followed.

The amount of water and glue added to the insulation fibers is a very important detail, and the manufacturer’s guides about it should be strictly respected. The mix shouldn't be applied too dry or too wet, to avoid it to fall out of the cavity or to avoid longer drying times.

Costs

Sprayed-on cellulose, fiberglass and mineral wool fiber insulation will cost you about $1 to $1.30 per square feet (to attain an R-19 wall).

That means a cost at least 50% higher than the traditional and typical batt insulation, but lower than sprayed foams.