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This page illustrates and describes the properties of cellulose building insulation materials. I've added these examples because of frequent questions about these materials. This document assists building buyers, owners or inspectors who need to identify building insulation materials and also people who need to recognize both asbestos materials (or probable-asbestos) in buildings as well as materials unlikely to contain asbestos - all by simple visual inspection.

In these articles we provide photographs and descriptive text various kinds of building insulation along with description of the characteristics of each material.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

CELLULOSE - building insulation identification guide

Modern cellulose building insulation is basically chopped newsprint, usually treated with a fire retardant chemical. As you can see in the photos above, it looks like fluffy gray papery material. The lighter colored chips may be wood fragments that have been added to this mix.

Cellulose insulation is usually blown-in to building cavities as an insulation retrofit or into attics where it is being added or where access is physically difficult.

Cellulose building insulation has been used in buildings since or before 1937 and continues to be installed in buildings (2008) in the U.S.

Cellulose insulation produced by some manufacturers is a mixture of chopped paper and wood fibers (sawdust).

Tips for Inspecting for Cellulose Insulation

What are the R Values and Effectiveness of Cellulose Building Insulation?

The thermal resistance or heat-loss resistance of cellulose insulation sold by Pal-O-Pak Insulation company, for a 10-inch depth, was reported as 0.635 per square meter. The product heat resistance ranged (by thickness) from 0.004 to 1.602 m²· K· W^-1. Modern blown-in cellulose building insulation has an R-value of about 3.70 per inch.

What these data and most reports of insulation products' resistance to heat loss do not include is the large impact on building heat loss of the degree of care with which any insulating product has been installed. Gaps between insulating materials and building surfaces can permit drafts which can overcome otherwise high "R" values that may be associated with the insulating material. (Just imagine a well-insulated home in the dead of winter but with a few windows open.)

Insulating materials that by their physical nature tend to fill in cracks and gaps without much human effort, such as blown-in products or foamed products, are likely to produce fewer air leaks and thus may be expected to improve the economy of heating or cooling a building when compared with construction where diligence was not a watchword.

To compare insulating material R-values see our Table of Properties of Insulating Materials

What is the Mold Resistance of Cellulose Building Insulation?

We suspect that building cavities insulated with fire-retardant treated cellulose insulation are a bit more resistant to mold-growth than cavities insulated with fiberglass, cotton, or some other materials. Our hypothesis is that the fire-retardant chemicals happen to also discourage fungal growth.

Manufacturers of Cellulose Insulation

Some of the cellulose manufacturers registered by NIST include

• National Cellulose Corp.,
• U.S. Insulation Sales Corp.,
• Pal-O-Pak Insulation Company (aka National Cooperatives, Inc.),
• United Materials Corporation, and
• Insul-Wool Insulation Corporation.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

INSULATION & VENTILATION INSPECTION & IMPROVEMENT
Insulation Material Identification Guide
  Asbestos Identification in Buildings
  Asbestos Pipe Insulation
  Asbestos-Free Insulation Materials
  Balsam Wool Batt Insulation
  Cotton Insulating Batts
  Cellulose loose fill insulation
    Cellulose Insulation Identification
    Cellulose Insulation Inspection
    Cellulose Insulation R-Values
    Cellulose Insulation Mold Resistance
    Cellulose Insulation Fire Resistance
  Concrete insulation, light-weight
  Fiberglass Insulation
  Foam Board Insulation
  Foam Insulation Types - Visual Id
  Homasote & Other Insulating Board
  Icynene Foam Spray Insulation
  Insects & Foam Insulation
  Mineral Wool - Rock Wool Insulation
  Mold in Fiberglass Insulation
  Mold in Foam Insulation
  Paper Duct Insulation
  Perlite Insulation
  POLYISOCYANURATE FOAM INSULATION
  POLYSTYRENE FOAM INSULATION
  RADIANT BARRIERS
  RIGID FOAM USE INDOORS
  Urea Formaldehyde Foam Insulation UFFI
  Vermiculite Insulation

• 3/07: thanks to Gary Randolph, Ounce of Prevention Home Inspection, LLC Buffalo, NY, for attentive reading and editing suggestions. Mr. Randolph can be reached in Buffalo, NY, at (716) 636-3865 or email: gary@ouncehome.com

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More Information on Building Diagnostic Inspections and Repairs

• Asbestos: How to find and recognize asbestos in Buildings - visual inspection methods, list of common asbestos-containing materials
• Asbestos HVAC Ducts and Flues field identification photos and guide
• Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
• Enviro-Scare: Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues
• Dust from the World Trade Center collapse following the 9/11/01 attack: the lower floors of this building contained spray-on fire-proofing asbestos materials.
• Asbestos Information Links: Asbestos Detection, Testing, Recognition, Hazards, Field Photos, and Information Sources, including health-related links such as legal services and information about mesothelioma and other cancers.
• Asbestos Identification and Testing References
• Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed the basis for current work by asbestos identification laboratories.
• Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
• Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone

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