Frequently Asked Questions

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Cellulose Insulation Quality

R-Value is only one factor to consider when choosing insulation.  The performance of an insulation material is also dependent upon reducing heat loss through air infiltration, convection and radiation.  Cellulose insulation reduces air infiltration and convection better than other insulation products with the same R-Value, giving cellulose insulation superior overall performance.

Yes!  The performance of Nu-Wool Premium Cellulose Insulation, Nu-Seal Spray Foam and ECOCELL products are backed by an industry-leading 10-year Energy Guarantee on heating and cooling bills. Nu-Wool Co., Inc. is the only manufacturer to offer this type of guarantee!

Cellulose insulation in walls will typically be more expensive than fiberglass batts due to higher installation costs.  However, the difference in cost is quickly recovered through greater savings on energy bills by using cellulose insulation. For attics, blown in cellulose and blown in fiberglass insulations are comparably priced.  
Cellulose insulation is less expensive than foam insulation.

All loose-fill insulation products can settle over time. By federal law and industry standards compensation for settlement is built into cellulose insulation coverage charts. When installed properly in accordance with the coverage chart, loose-fill cellulose insulation will not settle below the intended R-Value.  When Nu-Wool Premium Cellulose Insulation is properly installed in wall cavities to a density of 3.0 to 3.5 pounds per cubic foot using the Nu-Wool WALLSEAL System, it adheres to the studs, plates and sheathing, and will not settle.

Cellulose insulation has a Class A Fire rating.  It is treated with fire retardants to meet all federal, state, and local fire safety requirements.  Nu-Wool Premium Cellulose Insulation contains 100% borate-based fire retardants, and has been successfully tested in over 50 UL approved 1, 2 and 3- hour firewall designs.

Cellulose Insulation Installation Process

Under most conditions gypsum board can be installed 24 hours after a 2×4 wall cavity has been filled and 48 hours after filling a 2×6 wall.

Yes. Nu-Wool trains installers how to properly dense pack a cathedral ceiling .

Read more on the Cathedral Ceiling page.

Meeting Test Requirements & Building Codes

Section R 302.10 of the 2012 IRC requires cellulose insulation to pass the following tests:
  • ASTM E-84
  • Consumer Protection Safety Commission 16 CFR parts 1209 and 1404
  • Additionally all thermal insulation must follow the Federal Trade Commission rule 16 CRF part 460
As noted on our bags and in our literature, Nu-Wool Premium Cellulose Insulation is an Underwriters Laboratories Classified Product. Nu-Wool uses UL as an independent certified third party to conduct all of the required tests. A copy of compliance is available from Nu-Wool and from UL on their web site under “certifications.”  In addition,  UL Evalulation Report – UL ER8078001 confirms Nu-Wool Premium Cellulose Insulation meets building code requirements.
See UL classification documents R-8078 & R-8078-B, and UL Evaluation Report – UL ER80780-01

ASTM is responsible for writing the test standards. ASTM C-739 provides most of the test procedures while ASTM E-84 and E-970 provide the standard to determine flame spread and smoke developed as well as critical radiant flux, respectively.

ASTM C-739 outlines test procedures for the following physical properties of cellulose insulation:
  • Design Density
  • Critical Radiant Flux
  • Fungi Resistance
  • Odor Emission
  • Smoldering Combustion
  • Thermal Resistance
  • Moisture Vapor Sorption Corrosion
See UL classification documents R-8078 & R-8078-B

Yes, in fact there are over 50 fire wall assemblies using Nu-Wool Premium Cellulose Insulation listed on the UL website.

Read more on the Firewall page.

The 2012 International Residential Code defines 3 classes of vapor retarders:

  • Class I0.1 perm or less (i.e. sheet polyethelen, unperforated aluminum foil)
  • Class II1.0 perm or less and greater than 0.1 perm (i.e. kraft-faced fiberglass batts)
  • Class III10 perm or less and greater than 1.0 perm (i.e. latex or enamel paint)

Buildings in zones 1-3 do not require any class of vapor retarder on the interior surface of insulated assemblies. Zones 4-8 require nothing more than a Class III vapor retarder on the interior surface of many types of insulated assemblies, dependent upon the specific zone and wall construction components (ordinary latex paint qualifies as a class lll vapor retarder).   Consult the building codes that affect your area.

No.  Building codes, as well as most flue and chimney manufactures, require a minimum air space between flues and any combustible material.

Questions, Comments or Concerns?  Please contact us by email OR for more information, check out our YouTube Channel.

Energy Savings Calculator


The use of this calculator is limited to comparisons between energy costs of example homes only. The numbers shown do not represent actual dollar amounts or dollar savings from Nu-Wool Co., Inc. Your savings may vary. The calculations are based on typical new home construction, state average utility costs, new high efficiency HVAC systems, and typical weather for the state selected. These numbers do not include base utility costs such as water heating, lights, and appliances. If you have questions, please contact the Nu-Wool technical department at (616) 669-0100.