Cellulose Insulation vs. Fiberglass Insulation

5 ways to tell if your home needs better insulation


Unusually high energy costs


Drafty rooms and uneven temperatures


Cold floors and walls in the winter.


Mould in the basement


Ice dams or snow melting on your roof

Benefits of Insulation:


R-value measures the resistance of heat flow through a material – the higher the R-value, the better the material is at resisting heat flow. In most situations, we prefer the air and heat flow resistance of cellulose over that of fiberglass. At 3.5 per inch of material, the R-value of blown-in cellulose is 23% better per inch than fiberglass batts!
read more closeAccording to research done at the Oak Ridge National Lab, fiberglass loses up to 50% of its R-value in very cold conditions; making cellulose a better choice for homes in northern climates. In the summer, according to research by the Brookhaven National Lab, fiberglass loses 3 times more R-value than cellulose when attics reach 110 degrees (F) – very common in most areas of the country. Dr. Energy Saver and Attic Systems contractors blow in cellulose up to a depth of 17 inches (R-60), completely covering the wood floor joists, which have a low R-value and can transfer heat to and from the attic and home. Fiberglass batts are placed between floor joists, allowing for greater heat loss as air moves through the wood joists.

Air leakage

Air leakage through cracks, voids, and gaps in your home insulation is responsible for approximately one-third of an average home’s heat loss. Heat and comfort are also lost through convection; when drafty currents of air within the house, wall cavities or attics, move heat to other locations.
read more closeSince cellulose is blown in, it fills all the gaps, crevices, nooks and crannies in your attic, unlike batts that can leave gaps. Compared to fiberglass, cellulose is a superb air-blocker.


Air moving through a vented attic deposits dirt and dust into fiberglass batts; this is called wind-washing. Dirty fiberglass batts have a significantly reduced R-value.
read more closeBecause it is denser than fiberglass, cellulose is much more resistant to wind-washing.
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Cellulose is “Green”

Wet insulation of any type is bad. But cellulose is hygroscopic, meaning any moisture it encounters is dispersed throughout the material. This prevents liquid from accumulating in any one area. Cellulose can help dry out other materials in contact with it and does not support mold growth.

Cellulose insulation is safe.

Although cellulose is made of paper, thorough mineral treatment provides it with permanent fire resistance. Unlike fiberglass batts with paper backing, it doesn’t burn as you might expect ground up paper to. Despite competing industries stating otherwise, independent testing confirms that cellulose is safe and approved in all building codes. In fact, many professionals consider cellulose to be more fire-safe than fiberglass.
read more closeThis claim rests on the fact that cellulose fibers are more tightly packed, effectively choking wall cavities of combustion air, preventing the spread of fire through framing cavities. (Check out this YouTube video: The Big Burn).