The Benefits of Cellulose Attic Insulation

Side view of a man spraying cellulose insulation into a triangular space on one side of an attic.

One of most commonly-argued topics among attic insulation experts is whether fiberglass or cellulose attic insulation is better. In terms of overall performance and affordability, however, cellulose insulation is the more sensible choice, as this article explains.

The Purpose of Attic Insulation

Most attics have attic bypasses. Bypasses are concealed air passages that continuously leak heat from the interiors of the house. Warm air has a tendency to rise. Thus, it continuously moves toward these bypasses. This causes loss of heat, which in turn increases the energy spent heating the living space.

Therefore, heat lost through the attic adds to your energy bills. Damaged attics further reduce heat retention in the interior space by allowing colder air from the outside to enter the house.

Sometimes, water vapor is carried with the rising, warm air. This causes slow but continuous moisture seepage along the upper parts of the ceiling. The moisture tends to freeze during extremely cold conditions.

The moisture causes damage to the upper ends of the walls, particularly roofs that have a wooden under-surface. This causes peeling paint and rotting wood. The following are some areas where attic insulation is commonly needed:

Dropped and false ceilings

Attic space having numerous plumbing/electrical entry points

Chimney chaseways

Top-end of interior walls

Some notable advantages of using cellulose insulation in the attic follow.

Higher Thermal Resistance

Though cellulose insulation is often regarded as a budgeted form of attic insulation, it has been proven to offer better thermal resistance than the fiberglass alternative. Cellulose insulation is more effective because it is made of natural fibers that are inherently equipped with better insulation properties. They are poor conductors of heat.

Further, cellulose insulation doesn't require a vinyl coating. The fibers are resistant to moisture seepage and cracking in the cold.

R-value is a measure of the effectiveness of an insulation material. R-values for cellulose insulation are higher than for fiberglass insulation. In fact, fiberglass can lose some of its initial, retailed R-value when the weather gets extremely cold.

Ease of Installation

Spaces along walls and ceilings often present oddly-shaped cavities. The installation becomes more demanding if the gap is surrounded by plumbing installations, wiring, or air ducts. Thus, an insulation material that can be packed-in quickly and tightly is ideal for preventing air leaks.

Cellulose insulation is perfect for such insulation needs. It is commonly installed in the loose-fill format wherein it can be poured and compressed into any kind of an opening.

Moreover, the installation process can be made easier with a blowing machine. Cellulose insulation material is retailed in easy-to-use spray packages that homeowners can use without any professional help. Fiberglass needs to be cut according to precise measurements, making it difficult for do-it-yourself home improvement projects.


Fiberglass insulation is made from synthetic, glass fibers. These fibers are woven to form thin sheets, which are then compressed together.

Cellulose insulation material is essentially a recycled product. It is prepared from shredded paper and plant resins that are treated to become insulators. This fundamental difference between the two insulation materials makes cellulose a more affordable choice.