The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.
Question: How does Cellulose Insulation Stack Up Against Fiberglass or Rockwool Insulation?
I plan to retrofit 7 inches of blown insulation over the top of 6 inches of existing fiberglass insulation, and I would like to use blown-in cellulose.
How does cellulose insulation stack up against fiberglass or rockwool with respect to
Attraction to (resistance to) nesting rodents
Fire protection (fire resistance)
Thanks - David Stingle, Black Creek WI
The R-vale per inch of loosefill insulation varies depending on its installed density and product characteristics. For that reason, the most reliable way to buy loose-fill insulation is to specify the R-value - not the thickness - and install the correct number of bags per square foot, following the loose-fill or blown-in insulation coverage chart printed on all insulation bags.
The insulation chart also shows a minimum insulation thickness necessary to guarantee the desired R-value3.
The U.S. Federal Trade Commission (FTC) requires insulation manufacturers to make available to consumers an information sheet explaining this system.
Moisture absorption of cellulose insulation: Of the three insulations you named: blown-in or loose-fill cellulose, fiberglass, or rockwool, only cellulose will absorb moisture, but this is only a problem if it gets drenched, such as by roof leaks into an attic or building wall. The other two insulations will hold moisture only on their glass or mineral fiber surfaces.
Fire resistance of cellulose insulation: Of the three insulation products we are discussing, only cellulose is potentially flammable, if its fire retardant loses effectiveness over time (as some suspect of the dry-applied fire-retardants). Studies in the mid 1980's of the reliability of fire retardance of cellulose insulation over time were inconclusive. See Cellulose Insulation Fire Resistance for details.
As for rodent resistance of cellulose insulation, we (DJF) have observed that rodents are happy tunneling in just about any soft insulating material, but we have also observed that a different sort of pest, mold, is not generally found in cellulose insulation. We (DF) believe based on our own field and lab investigations that the fire retardant chemicals used to treat cellulose insulation appear to also resist mold growth.
Watch out: other insulation properties such as air flow resistance and moisture resistance may be very important in some cases, such as choosing an insulation to use in or over a crawl space that may be damp, or against basement foundation walls - Ed. See INSULATION INSPECTION & IMPROVEMENT and FIBERGLASS INSULATION MOLD for examples- Ed.
The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article.
Q&A on Cellulose Pros & Cons - PDF version, use your browser's back button to return to this page. Original article, Solar Age Magazine, December 1985/January 1986, adapted and updated for InspectAPedia.com December 2010.
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Solar Age Magazine was the official publication of the American Solar Energy Society. The contemporary solar energy magazine associated with the Society is Solar Today. "Established in 1954, the nonprofit American Solar Energy Society (ASES) is the nation's leading association of solar professionals & advocates. Our mission is to inspire an era of energy innovation and speed the transition to a sustainable energy economy. We advance education, research and policy. Leading for more than 50 years.
ASES leads national efforts to increase the use of solar energy, energy efficiency and other sustainable technologies in the U.S. We publish the award-winning SOLAR TODAY magazine, organize and present the ASES National Solar Conference and lead the ASES National Solar Tour – the largest grassroots solar event in the world."
Steve Bliss's Building Advisor at buildingadvisor.com helps homeowners & contractors plan & complete successful building & remodeling projects: buying land, site work, building design, cost estimating, materials & components, & project management through complete construction. Email: firstname.lastname@example.org
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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Asbestos: How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials
Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print).
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 Research Council, BRC, nee Small Homes Council, SHC, School of Architecture, University of Illinois at Urbana-Champaign, brc.arch.uiuc.edu. "The Small Homes Council (our original name) was organized in 1944 during the war at the request of the President of the University of Illinois to consider the role of the university in meeting the demand for housing in the United States. Soldiers would be coming home after the war and would be needing good low-cost housing. ... In 1993, the Council became part of the School of Architecture, and since then has been known as the School of Architecture-Building Research Council. ... The Council's researchers answered many critical questions that would affect the quality of the nation's housing stock.
How could homes be designed and built more efficiently?
What kinds of construction and production techniques worked well and which did not?
How did people use different kinds of spaces in their homes?
What roles did community planning, zoning, and interior design play in how neighborhoods worked
"An Example of Colonial Paneling", Norman Morrison Isham, The Metropolitan Museum of Art Bulletin, Vol. 6, No. 5 (May, 1911), pp. 112-116, available by JSTOR.
"Energy Savers: Whole-House Supply Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Supply_Vent.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11880?print
"Energy Savers: Whole-House Exhaust Ventilation Systems [copy on file as /interiors/Energy_Savers_Whole-House_Exhaust.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11870
"Energy Savers: Ventilation [copy on file as /interiors/Energy_Savers_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Natural Ventilation [copy on file as /interiors/Energy_Savers_Natural_Ventilation.pdf ] - ", U.S. Department of Energy
"Energy Savers: Energy Recovery Ventilation Systems [copy on file as /interiors/Energy_Savers_Energy_Recovery_Venting.pdf ] - ", U.S. Department of Energy energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11900
"Energy Savers: Detecting Air Leaks [copy on file as /interiors/Energy_Savers_Detect_Air_Leaks.pdf ] - ", U.S. Department of Energy
"Energy Savers: Air Sealing [copy on file as /interiors/Energy_Savers_Air_Sealing_1.pdf ] - ", U.S. Department of Energy
Falls and Related Injuries: Slips, Trips, Missteps, and Their Consequences, Lawyers & Judges Publishing, (June 2002), ISBN-10: 0913875430 ISBN-13: 978-0913875438 "Falls in the home and public places are the second leading cause of unintentional injury deaths in the United States, but are overlooked in most literature. This book is unique in that it is entirely devoted to falls. Of use to primary care physicians, nurses, insurance adjusters, architects, writers of building codes, attorneys, or anyone who cares for the elderly, this book will tell you how, why, and when people will likely fall, what most likely will be injured, and how such injuries come about. "
Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -
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