Photo Guide to Asbestos Paper Wrap on Air Ducts InspectAPedia® -
How to recognize asbestos duct wrapping materials in buildings
Photographs of asbestos paper duct wrap in buildings
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This page illustrates asbestos paper duct wrap that was usually applied to the exterior of metal heating ducts in buildings prior to 1970. This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple
visual inspection. We provide photographs and descriptive text of asbestos insulation and other asbestos-containing products
to permit identification of definite, probable, or possible asbestos materials in buildings.
While an expert lab test using polarized light microscopy may be needed to identify the specific type of
asbestos fiber, or to identify the presence of asbestos in air or dust samples, many asbestos-containing building products
not only are obvious and easy to recognize, but since there were not other look-alike products that were not asbestos, a visual identification of this material can be virtually a certainty in many cases.
Also see Asbestos HVAC Ducts a field identification guide to
visual detection of asbestos in and on heating and cooling system ducts and flue vents.
ASBESTOS PAPER DUCT INSULATION - Asbestos paper insulation on hot air heating duct or air conditioning duct exterior
This asbestos paper-like material is on the exterior of a hot air supply duct. On homes even into the 1960's we find this material used to
seal joints in metal heating ducts.
On older homes from perhaps 1920 the material was often wrapped around the entire duct exterior rather than
simply at the joints.
Since the duct is normally under positive pressure, any openings in the duct would be more likely to leak hot air out than to suck asbestos fibers into the air path.
If on the other hand we found asbestos material in the air path or on a return duct it would be a more urgent repair topic.
Examples of Asbestos Suspect Material Commonly Found on Heating and Air Conditioning Systems in Buildings
We often see what may be asbestos containing insulating material on the heating system, including the following:
Cement asbestos "millboard" used as a partial heat shield on wall/ceiling surfaces.
White corrugated insulating material on and hanging from pipes, white paste material surrounding certain plumbing joints.
White "paper" wrapped on outside of some heating ducts.
White woven material used as flexible joint between some heating ducts.
White woven material used as flexible joint in the vibration damper between air handler the duct work.
Heating and Cooling Duct Asbestos Paper Wrap Risks
The photograph shows asbestos paper duct wrap that has been damaged and is in poor condition. Is this material a hazard? Is it
releasing asbestos fragments or fibers into the heating system air ducts?
OPINION-DF: We have not located conclusive data or studies which evaluate hazards regarding specifically the presence of asbestos paper wrap on ductwork
in residential buildings. Like other asbestos fibers in buildings from other sources, if disturbed and distributed in the living area of a building at
levels above government standards, there is a potential health risk.
We t is also a
potential economic risk as future buyers may be concerned about this material. Disposal costs for this material are increasing.
Depending on condition and location of asbestos material, treatment ranges from doing nothing to complete removal.
Removal could involve significant costs.
General advice about asbestos suspect paper wrap material on heating or cooling duct work:
You should obtain proper technical information and health and safety guidelines before attempting to do anything with this material.
It is the breathing of fibers when this material is disturbed, not it's mere presence, which is considered a health risk.
When the material is not found in living areas in poor condition treatment is not usually an emergency and you have time
to become informed, obtain estimates, and select an appropriate course of action.
If asbestos materials are inside the duct
work, such as used for lining of a stud or floor joist bay which serves as an air duct, or perhaps where used as the vibration damper
material connecting an air handler to the supply plenum of a system, because of the possible release of fibers continuously and directly
into the path of moving air in the building, this material should be removed.
If asbestos materials have
been disturbed inside a building without proper containment and cleanup, additional evaluation of the
level of asbestos particles in building may need to be evaluated as additional expert cleaning might be needed.
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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
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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