What distinguishes one cellulose from another? I've noticed a very wide range of pricing for packaged cellulose and don't understand why.

Asked by Stephan Pollard
Fayetteville, AR

I'm preparing to have cellulose blown into the attic and existing walls of a 1960's built range house. I've come across a huge difference between the material costs cited by some cellulose installers and those of other cellulose installers and then what is sold in big box home improvement stores. How might these differences be explained? Is it due to the attributes of the cellulose used? What should I look for in a cellulose?


Polly Osborne, FAIA, LEED AP

Answered by Polly Osborne, FAIA, LEED AP

Los Angeles, CA

Polly Osborne Architects

April 9, 2013

There are a number of things that can affect the price of cellulose insulation.

The main differences between various products are: weight of bag, additives, processing techniques, manufacturer focus, and coverage.

The cost variance is likely to 15-20% between best and basic cellulose product. If it is more than that, you might be getting taken for a ride.

Fire retardants

Cellulose insulation uses boric acid and ammonium sulfate as a fire retardants.

  • Boric acid [Borates] is a pretty benign substance that few people are sensitive to. It makes up 100% of some products and those are the more expensive ones.
  • The second common fire retardant is ammonium sulfate, which is mixed with borates to make a less expensive fire retardant.

While equally good as a fire retardant, ammonium sulfate can off-gas ammonia. This is usually short lived and dissipates through attic vents, but the very chemically sensitive are going to want to avoid the ammonia sulfate.

There are, of course, degrees here, with some manufacturers using a very small amount of ammonia sulfate, which then has very little off gasing.

To quote Cell Pak, a cellulose supplier:
"We feel that the 100% boric acid formulation will increase the insect resistance and ammonia will not be released when moisture and heat are present."

Paper content

Another affect on price has to do with the source paper.

Greenfiber for instance, uses recycled paper that has been both machine and human inspected for purity. That means they have an extensive process for picking out plastics, glossy Christmas wrapping and other contaminants that end up in the paper recycling bins. As you can imagine, this process needs to be quite rigorous.

Beyond the product alone

Yet another reason for price differences is the size, professionalism and services the company offers.

  • Do they have good support for their products?
  • Can they supply you with independent testing for their products?
  • Are they UL listed?
  • How big is the company and how long have they been around?
  • What is the warranty on their products?
  • Do they offer technical support?
  • Do they have a web site that offers support for architects, builders, code officials and home owners?


Lastly is the question of coverage.

While the product coverage will be listed on the bag, the actual coverage will depend on the skill of the applicator and the machine they use to apply the product and the manufacturing process.

Thank you to the following people for helping me respond to this question:

Tagged In: cellulose insulation

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