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Not All Cellulose Insulations are Created Equal

March 31, 2010

Many people think cellulose insulation is the same product no matter who makes it. In Fact, nothing could be further from the truth. In the product itself, there are only a few ingredients but they can make a big difference.

Cellulose has 2 primary materials, paper and fire retardants. Let's look at the paper first. A good cellulose uses paper that has a long fiber in it such as newspaper. Many office papers have very short fibers and can be very dusty in the product. Most cellulose manufacturers get their product from one of 2 sources: Co-mingled paper or Over-issued news print. Co-mingled is the source that consumers put on the curb about every 2 weeks. It can also be the paper placed in the bins at a transfer station. Although many people try to be vigilant on the paper they recycle, often times plastic bags, pizza boxes (with food on it), glass, foil, and other non-paper products end up in the recycle. These 'contaminants' can reduce coverage, ruin machines, clog hoses, and end up in you wall of attic.

Conversely, over-issue newsprint is the paper on the newsstand today that does not sell and is returned to the news company. This paper is clean and would otherwise be thrown away. National Fiber uses over-issued newsprint and even goes a step further by hand-sorting the glossy stock out of the paper including plastic bags and other 'contaminants.' This clean paper allows for better coverage (no heavy items to reduce coverage), fewer clogs caused by foreign matter, prolonged life of the airlock seals, and confidence that only cellulose (no food, metal or plastic) in the wall/attic. In addition, since the coverage rates are better, the better quality paper source can provide as much as 30% better coverage.

Fire retardants are vitally important in the cellulose because without it, houses would be in serious fire danger. All cellulose products must have a minimum of 15% fire retardant. Half of this must be boric acid. Boric acid is very similar to the Borax (20 mule team) you can buy in the grocery store. It is a natural mineral from the earth that is used in many products including cosmetics and eye washes. Boric acid, when under fire, will melt and form a protective char that stops the fire from spreading. In addition, borate has mold/mildew and insect repellant properties. I have been to many trade shows and spoken to many firemen who love houses with cellulose as it usually saves the house from extensive damage. Many companies will cut the borate in half or more with Ammonium Sulfate. The Ammonium Sulfate has the same fire retardant properties and is about $1.50 less in cost per bag of cellulose. This sounds great but has significant drawbacks. First of all, Ammonium Sulfate blends lack the mold/mildew and insect resistance that an all borate blend provides. In addition, Ammonium Sulfate products can, in some circumstances, become corrosive when they are damp or wet. This means pipes, nails, hangers, and even metal treated lumber can become corroded. On the installer side of things, Ammonium Sulfate products can burn the open cuts on the skin.  All borate cellulose is considered to be the safest and highest quality on the market.

There are many companies that rely on people thinking all celluloses are the same and they want the one with the lowest price. That is why many use a co-mingled paper and blend the borate with ammonium sulfate. What they really offer is a product that gets reduced coverage and can corrode the metal in your home.

To get a better understanding of the coverage, let's look at insulating a 1500 sq. ft. attic to an R-38. National Fiber's Cel-Pak gets 23.54 sq. ft per bag on an R-38 attic. This means you would need 64 bags of material. Green Fiber's new all borate Retrofit product gets 18.1 sq. ft. per bag in an R-38 attic. This means you would need 83 bags of Green Fiber. Assume you pay $8.25 for the Green Fiber and $10.00 for the National Fiber Cel-Pak...Green Fiber would cost $684.75 in material while National Fiber's Cel-Pak would cost $640. A $44.75 difference in the favor of National Fiber where the cellulose per bag cost difference is $1.75. Plus, you are getting a clean, all borate product!