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This page discusses the potential hazards of transite (cement asbestos) air ducts - asbestos fiber release, radon, and indoor air quality concerns, and duct collapse when transite air ducts are is found in buildings.

Transite pipe, an asbestos-cement product, was used for HVAC ducts and for chimney or flue material to vent gas-fired appliances. Cement-asbestos transite pipe may also have been used for water piping in some communities. This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection. Transite air ducts in slabs often collect water, mold, pathogens. 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 or water 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.

Readers concerned with ice or water leaks into or out of HVAC ductwork should also see  WET CORRODED DUCT WORK and see WATER & ICE IN DUCT WORK as well as FROST BUILD-UP where we discuss build-up of ice on the cooling coil in air conditioning air handler units.

Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © 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.

Readers should also see:

• ASBESTOS HVAC DUCTS - Guide to Identification of Asbestos Materials On or In Heating and Cooling Duct Work: carbon monoxide hazards of transite chimneys and vents
• ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY - Environmental Hazard Detection, Testing, Repair, Illness, Symptoms, & Prevention in Buildings
• IDENTIFICATION of ASBESTOS in BUILDINGS - Asbestos Identification in Buildings: How to find & identify asbestos-containing materials
• Transite Pipe Air Ducts - Hazards of Asbestos-containing Transite Pipe HVAC Ducts: duct collapse, mold, radon, asbestos fiber release
• Transite Pipe Chimneys & Flues - Guide to Identifying Asbestos Transite Chimneys & Flues & their Hazards in Buildings
• Transite Pipe Water Supply Piping - Guide to Identifying Asbestos Cement Transite Water Pipes & their Hazards in Buildings

Also see Micro-Photographs of Dust from the World Trade Center collapse following the 9/11/01 attack. Links to U.S. government and other authoritative research and advice are included. [Page top photo of transite duct material courtesy of Thomas Hauswirth, a Connecticut home inspector.

TRANSITE PIPE HVAC DUCTS - Asbestos Heating or Air Conditioning Duct Material Warnings

Transite pipe, which contains significant percentage of asbestos fibers, was often used for heating ducts and on occasion heating and cooling ducts in older buildings. The transite pipe was used in a buried-in-slab construction methods which placed the transite piping below or in a building floor slab. Asbestos-containing transite pipe HVAC ducts were also used in exposed areas such as shown in the crawl space photograph at the top of this page. Transite Duct Asbestos Warnings & Hazard Details Transite ducts used for HVAC air flow, especially when used buried in building concrete floors or slabs, may break, collapse, leak water in (forming a mold and bacterial reservoir in the HVAC system, or may release asbestos and other particles in building air when the HVAC system is operating. An up-flow or down flow furnace in a building with concrete slab and with perimeter duct work raises some important health and cost questions: The photograph above shows a transite cement asbestos heating duct in a carpeted floor slab. We recommend that in-slab heating or air conditioning ducts made of transite be sealed and abandoned, and alternate heat sources installed. This improvement removes an asbestos hazard, a flooded duct and mold hazard, and in some locales, also a radon gas entry point. The photograph shows the edges as well as surface of the transite material. Transite pipe HVAC ducts get quite dirty and are not always easy to identify. [Photo and comments on transite in-slab HVAC ducts courtesy of Roger Hankey, a Minnesota home inspector.]

• Asbestos hazards of transite ducts: Cementious duct material may contain asbestos. What is this "cement" duct work made of Cement and asbestos fibers.
  
  How much asbestos is in Transite pipe? While it's cementious, transite ducts or even transite pipe used for heating flue vents is a potential asbestos hazard in buildings. Transite pipe typically contains about 15% to 25% asbestos fibers, typically fibrous chrysotile asbestos.
  
  A careful asbestos testing lab may report both fibrous and fragmented asbestos which can occur in still smaller pieces (thus more easily remaining airborne and increasing human exposure to asbestos).
  
  The balance will be cement and possibly other fibers or binders. If transite pipe is damaged or is cut mechanically (such as by using power equipment), friable, airborne asbestos fibers may be generated - a health and costly cleanup concern.
  
  
• Air quality hazards of in-slab duct systems: include water leaks into the duct system which can in turn generate a mold or bacterial hazard or can cause softening, collapse, and blockage of the in-slab transite pipe duct. While there are companies offering duct cleaning and duct sealing services, we remain cautious that such a "sealing" project creates a false sense of confidence that no remaining duct issues exist, causing the occupants to miss the discovery of future leaks and in-duct problems.
  
  
• Radon entry through in-slab duct systems: can occur in areas where radon is present at problem levels in the soils. In particular, because a return air duct is often at negative pressure (when the blower is operating), the movement of radon gas from the soil into the building air through a leaky in-slab duct can be significant, certainly greater than the movement into the building from other openings such as through a basement slab crack.
• Asbesos fiber release hazards during removal of demolition of transite piping are discussed at Transite Pipe Chimneys & Flues.

Incorrect spellings of transite asbestos piping or transite duct material that we've seen include transit pipe, transit ducts, transite chimneys, transide pipe, transide ducts, and transight pipe or transight ducts. "Transite" is the correct spelling.

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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
ASBESTOS IDENTIFICATION IN BUILDINGS
Asbestos Risk Assessment
Asbestos in Good Condition
Asbestos in Poor Condition
Asbestos Removal, Amateur, Incomplete
Asbestos Foamed-Over
Asbestos Air Ducts
Asbestos Air Duct Vibration Dampers
Asbestos Pipe Insulation
ASBESTOS REGULATION Update
Asbestos Roofing Materials
Asbestos Siding Materials
Asbestos in unusual places
Carbon Nanotube Materials
Ceiling Tiles Containing Asbestos
Fireproofing containing Asbestos
Floor Tiles Containing Asbestos
Paper Duct Insulation Containing Asbestos
Transite Pipe Air Ducts
Transite Pipe Chimneys & Flues
Vermiculite Insulation Containing Asbestos
Other Asbestos-Containing Materials
Asbestos Under the Microscope

Insulation Material Identification Guide
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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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