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Properties of Cellulose Building Insulation Materials MoldAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Photo guide to identifying & inspecting cellulose building insulation
• Photo guide to identification of different building insulation materials
• Properties and R-values of different building insulation products
• Description of Non-asbestos materials sometimes mistaken for asbestos in buildings

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 2008 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

Don't cut a big hole to look for blown-in cellulose insulation - as you can see in this photo, it may simply fall out.

If you inspect an older building's basement or crawl space it may be easy to see if cellulose insulation has been blown into the building's walls.

Check at the building's sills atop the foundation walls.

Often openings in building walls permit blown-in cellulose to fall onto the top of the sill as you can see in our photo at left.

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

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.

Mold resistance of cellulose 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.

Fire resistance of cellulose insulation

Note that according to the North American Insulation Manufacturers' Association, the chemical treatment of cellulose insulation does not make cellulose insulation "non-combustible" nor does it prevent smoldering type ignition of the material. Cellulose insulation is tested for fire resistance using ASTM C-739.

It has also long been our opinion that the chemical retardant treatment, however effective it may be, may deteriorate over time or especially if the insulation is exposed to water - say from a roof or wall leak. NAIMA has a similar view.

In sum according to NAIMA "fire retardant treated cellulose insulation" is not necessarily completely fireproof.

But then, a chief competitor of cellulose insulation, fiberglass insulation products are also not exactly fireproof - the kraft paper to which lots of fiberglass insulation is affixed to ease installation (and provide somewhat of a vapor retarder), for example can be set afire and it is possible that some of the binder resins may support combustion.

ASTM C-665 is the test standard for fire resistance of mineral fiber batts and rolls, and ASTM C-764 is the fire test standard for loose fill mineral insulation. (In industry speak, fiberglass is considered a mineral fiber along with rock wool or mineral wool insulations.)

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.

IDENTIFICATION of ASBESTOS in BUILDINGS

INSULATION INSPECTIONS
  Asbestos Pipe Insulation
  Vermiculite Insulation
Asbestos-Free Insulation Materials
  Balsam Wool Batt Insulation
  Cotton Insulating Batts
  Cellulose loose fill insulation
  Fiberglass Insulation
  Mineral Wool/Rock Wool Insulation

Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author/editor of the InspectAPedia ^TM Website
• 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
• 06/07: thanks for photographs of transite asbestos heating ducts, courtesy of Thomas Hauswirth, Managing Member of Beacon Fine Home Inspections, LLC and (in 2007) Vice President, Connecticut Association of Home Inspectors Ph. 860-526-3355 Fax 860-526-2942 beaconinspections@sbcglobal.net
• Technical reviewers are invited to comment or ask questions - contact us

More expert information on Asbestos Identification, Recognition, & Testing

More Information on Asbestos Contamination, Other Airborne Fiber Hazards, & 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

Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Research & Advice

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Home Inspection Construction Consulting Services & advice for home buyers

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

Contact Daniel Friedman for website content suggestions or for fee-paid consulting

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