Building Officials FAQ

Building Official Cellulose Wall

Q: What is the R-Value of Nu-Wool Premium Cellulose Insulation?
A: 3.8 per inch.

Q: What requirements are there for thermal insulation?
A: 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

Q: How do I know Nu-Wool Insulation has passed the required tests?
A: As noted on our bags and in our literature, Nu-Wool Premium Cellulose Insulation is an Underwrites 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 Evalulation Report - UL ER8078001

Q: Who designed the tests?
A: 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.

Q: What is the insulation tested for?
A: 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

Q: Can Nu-Wool Insulation be left exposed?
A: Yes.  ASTM test E-84 is used to determine the flame spread and smoke developed from the insulation. With a flame spread of 15 and a smoke developed of 5, Nu-Wool is considered a class A building material.

Q: Can Nu-Wool be used in firewalls?
A: Yes, in fact there are over 50 fire wall assemblies using Nu-Wool Premium Cellulose Insulation listed on the UL website.

See Firewall page

Q: What testing is done for firewalls?
A: ASTM test standard E-119 is used by an accredited lab to do live burns of actual wall sections to determine how long the assembly will hold up in either a fully loaded condition as in a bearing wall or in a free standing wall used only for partitions.

See Firewall page

Q: What do the building codes say about vapor retarders?
A:  The 2012 International Residential Code defines 3 classes of vapor retarders:

Class I 0.1 perm or less (i.e. sheet polyethelen, unperforated aluminum foil)
Class II 1.0 perm or less and greater than 0.1 perm (i.e. kraft-faced fiberglass batts)
Class III 10 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.

Q: May Nu-Wool Premium Cellulose Insulation be used to dense pack a cathedral ceiling space and eliminate the attic venting?
A: Yes. Nu-Wool trains installers how to properly dense pack a cathedral ceiling .

See Cathedral Ceilings page

Q: How soon can drywall be installed after using the Nu-Wool WALLSEAL system to install Nu-Wool Premium Cellulose Insulation?
A: Under most conditions gypsum board can be installed 24 hours after a 2x4 wall cavity has been filled and 48 hours after filling a 2x6 wall.

See 3-Part Specification page, part 3.2

Q: Can Nu-Wool Premium Cellulose Insulation be used to seal around chimneys and heating appliance exhaust flues?
A: No.  Building codes, as well as most flue and chimney manufactures, require a minimum air space between flues and any combustible material.