Frequently Asked Questions

The more you know about Greenfiber cellulose, the more you’ll agree it’s the best insulation you can use. Here are some of the questions people ask us a lot.

That depends on four things: the recommended R-value, your climate, the type of heating and cooling system you have, and the section of the house you plan to insulate. For the recommended levels of insulation, the Department of Energy publishes this map with the R-values they recommend.


A lot of stores will let you use the machine for free with a minimum purchase of Greenfiber. But even if you need to rent the machine, you won’t need it for long and your whole job should still be economical.

It’s made of cellulose, which is a basic part of plants (think wood pulp). Our cellulose insulation consists of up to 85% post-consumer paper fiber. It also contains additives for fire resistance, and some has been treated with boric acid for protection from pest infestation and moisture. What it doesn’t contain is also important: there’s no formaldehyde, asbestos or fibers from textiles, fiberglass or mineral wool in Greenfiber.

We have a long list of additional fire safety credentials: Greenfiber has a Class1 fire rating from E 84 testing and is permitted as a fire block. It’s also manufactured to meet strict Consumer Product Safety Commission (CPSC) fire safety regulations, and all our products meet American Society for Testing and Materials (ASTM) C 739 and E 84 tests. Plus, Greenfiber has a growing list of fire resistance-rated buildings assemblies, of both wall and floor-ceiling type, that are listed in the Certification Directory of Underwriters Laboratories. All our products are classified by UL and carry the UL mark on every bag. Bottom line: you’re safer with Greenfiber than without it or than with any other type of insulation.

Nope.  Accelerated aging tests (CAN/CGSB-51.60 M-90) performed on cellulose insulation have shown that there’s no noticeable degradation over time. In addition, Greenfiber offers a limited lifetime warranty, which includes the permanency of the fire retardant treatment we use, for the life of the structure.

Where air goes, sound follows. Our sound control quality is due to Greenfiber’s density and its ability to fill any cavity since it’s easily blown into voids and gaps that could allow for sound transmission. Greenfiber is especially good at blocking airborne sound from traffic noise, airplanes, radios, televisions and conversation.

Greenfiber Insulation meets or exceeds standard industry tests (ASTM C 739) for corrosion resistance, performed on steel, copper and aluminum.

You bet. Our insulation is ideal for providing additional R-value over existing attic insulation since it completely fills voids and gaps left open by other forms of insulation. It can also be installed in existing uninsulated exterior walls through various methods.

Actually, it’s really easy. No kidding. There’s no lifting heavy rolls up through attic openings. Plus there’s no measuring, cutting or trying to fit stuff into tight nooks and crannies. You’ll just need two people — one to put the insulation in the blowing machine and another to blow the insulation to the desired thickness, which is easily measured by attic rulers. It can also be installed in existing uninsulated exterior walls through various methods such as the two-hole installation method and tube method.

It will settle in attics until it reaches a stable density, as will other types of blown insulation. Coverage charts have already taken this into account, so it’s nothing to worry about. In sidewalls, Greenfiber will not settle when properly installed.

Yes, it’s safe. Greenfiber is itch free to the touch, and it doesn't have any glass fiber that can cause irritation when you're handling it. In compliance with Material Safety Data Sheet standards, Greenfiber produces dust classified as “nuisance,” and is only present during installation.