Insulation: Compare Before you Buy.
Here are the real answers to real questions concerning two leading blown insulation products: fiberglass and cellulose.
Take a look at the real purpose of insulation-comfort, safety, permanence, and of course, thermal efficiency-and you'll see that Fiberglass outperforms cellulose every time.
1. Which insulation offers the highest R-Values per inch?
In open attic installations, the thickness of insulation is rarely a consideration. In sidewalls, however, where thickness can be important, fiberglass provides an R-Value of R-15* in a 3 1/2" cavity-which is greater than cellulose provides in a similar-sized cavity.
Accordingly, even though cellulose promotes a higher R-Value per inch, in fact, it is R-Value that is important, not R-Value per inch, when insulating a wall cavity or other restricted area.
*R means "resistance to heat flow." The higher the R-Value, the greater the insulating power. To get the marked R-Value, it is essential that this insulation is installed properly.
2. What about air infiltration problems?
Properly installed in side walls, both cellulose and fiberglass perform equally well-when looking at air infiltration.
The cellulose industry claims that, when their product is spray applied, it makes home more airtight and resistant to air infiltration than does fiber glass insulation.
In fact, thermal insulation-whether cellulose or fiber glass- when installed in sidewalls has very little to do with air infiltration. The U.S. Dept. of Energy estimates that up to 40% of a home's heat loss can be from air infiltration. But only 4% of the total heat loss from air infiltration occurs through wall cavities. Air infiltration through wall cavities can and should be controlled with proper caulking and sealing of sill plates, header plates, doors, windows, electrical outlets, and other openings.
3. What about moisture absorption?
Fiberglass Fiber Glass Insulation does not absorb and retain moisture. If wet, it dries, retaining it's original R-Value.
Cellulose is made of ground-up newspapers and it does absorb moisture. This is a real problem because it can pat down and permanently lose R-Value.
4. Is there a fire concern with either product?
Fiberglass is permanently noncombustible.
Cellulose insulation is naturally flammable and must be treated with chemicals to make it fire retardant. Even properly treated, cellulose can smolder when exposed to heat as low as 450 degrees F.
5. In a home fire, can insulation contribute to its spread?
Fiberglass is noncombustible and cannot contribute to the spread of fire. If it comes in contact with the prolonged heat of a fire, it will simply melt.
Cellulose, in spite of being treated with fire-retardant chemicals, may begin to smolder if it comes into prolonged contact with a heat source, such as a recessed light. This slow "smoldering" can continue, possibly leading to the combustion of nearby flammable material-such as roof beams.
6. Does either product promote corrosion?
Fiberglass contains no chemicals that can corrode pipes and wiring.
When sulfates are used to treat cellulose for flammability, there have been documented cases where the chemicals have been shown to cause corrosion of pipes, wires, or metal nailing plates for roof trusses. This might also be a concern when used with steel stud construction.
7. Does either product settle after installation, causing reduced thermal performance?
With Fiberglass there is virtually no settling.
Cellulose manufacturers concede that their insulation settles by approximately 20% from it's installed thickness.
8. How do the two products compare in regard to dust?
Fiberglass is considered by many installers to be the cleanest of all blown-in insulation products.
Those who install cellulose know that it creates very high levels of visible dust.
9. Is weight a consideration when choosing insulation?
Fiberglass is extremely lightweight. It poses no threat to ceiling construction when installed at any desired thickness or R-Value.
Because of its greater weight, cellulose could cause problems in certain installations. Weight limitation recommendations published by U.S. Gypsum show that there is potential for ceiling drywall to sag with cellulose at R-Values above R-30 when the cellulose is installed over traditional 1/2" ceiling drywall, 24" on center.
10. Are there health concerns with insulation products?
Fiberglass is probably one of the most tested building products in the world. Research into the health aspects of fiber glass spans more than 50 years, and in recent years tens of millions of dollars have been spent on both human and animal studies. The weight of scientific evidence has shown no causal relationship between exposure to fiber glass and cancer or non-malignant respiratory disease in humans. Virtually all scientists agree that fiber glass insulation is safe to manufacture, install and use when simple recommended work practices are followed.
In spite of the fact that wood dust is a known carcinogen and boric acid, borax, and sulfates (often used to make cellulose fire retardant) are all considered toxic materials, and can pose health threats over time, there has been little health testing or research on cellulose insulation.
Choose Fiberglass for Long-lasting Quality
A home is often the biggest investment a person undertakes…and the materials chosen to protect and enhance that home are a major consideration. Contractors and homeowners who've made the comparisons and checked the facts choose Fiberglass Fiber Glass Insulation.
Fiberglass offers outstanding thermal performance. It's noncombustible, clean, safe, and lightweight. It won't settle, cause corrosion, or absorb moisture. Fiberglass is one of the best, long-lasting investments that you can make in any home.
Fiberglass-For Quality, For Safety, For Peace of Mind