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ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
ASBESTOS & FIBER CEMENT ROOFING
ASBESTOS MATERIAL REGULATIONS
ASBESTOS REGULATION Update
ASBESTOS FLOORING HAZARD REDUCTION
ASBESTOS-FREE INSULATION MATERIALS
ASBESTOS IDENTIFICATION IN BUILDINGS
ASBESTOS ROOFING / SIDING DUST
ROOFING INSPECTION & REPAIR
ASPHALT ROOF SHINGLES
ATTIC CONDENSATION CAUSE & CURE
BEST CONSTRUCTION PRACTICES GUIDE
BEST ROOFING PRACTICES
BUILDING SAFETY HAZARDS GUIDE
BUILT UP ROOFS
CATHEDRAL CEILING INSULATION
CATHEDRAL CEILING VENTILATION
CERTIFICATIONS for ROOFING CONTRACTORS
CHIMNEY INSPECTION & REPAIRS
CHIMNEY FLASHING Mistakes & Leaks
CHOOSING A ROOFING CONTRACTOR
CLAY TILE ROOFING
CLAY, CONCRETE, FIBER CEMENT TILE INSTALLATION
COLD WEATHER ROOF TROUBLE
COOLING LOAD REDUCTION by ROOF VENTS
DEBRIS STAINING on ROOFS
DECKS, ROOFTOP CONSTRUCTION
DEFINITIONS of ENGINEERED WOOD OSB LVL etc
DISASTERS: BUILDING INSPECTION & REPAIR
DISPUTE RESOLUTION on ROOF JOB PROBLEMS
ENERGY SAVINGS in buildings
EPDM, RUBBER, PVC ROOFING
EPDM ROOF LEAK REPAIRS
EXTRACTIVE BLEEDING on SHINGLES
FELT UNDERLAYMENT REQUIREMENTS
FIBER-WOOD & FIBERBOARD ROOFING
FIRE RATINGS for ROOF SURFACES
FIRE RETARDANT PLYWOOD
FLASHING on BUILDINGS
FLASHING, ASPHALT SHINGLE VALLEYS
FLASHING, CHIMNEY Mistakes & Leaks
FLASHING, CLAY TILE ROOFS
FLASHING MEMBRANES PEEL & STICK
FLASHING for METAL ROOFS
FLASHING ROOF WALL DETAILS
FLASHING ROOF-WALL SNAFU
FLASHING SIDING DETAILS
FLASHING WALL DETAILS
FLASHING WINDOW DETAILS
FLASHING WOOD ROOF DETAILS
FLAT ROOF MOISTURE & CONDENSATION
GALVANIC SCALE & METAL CORROSION
GREEENHOUSE / SOLARIUM ROOF LEAKS
GUTTERS & DOWNSPOUTS
HAIL DAMAGED SHINGLES
HEAT TAPES & CABLES for ROOF ICE DAMS
HOT ROOF DESIGNS: UN-VENTED ROOF SOLUTIONS
HOUSEWRAP INSTALLATION DETAILS
HUMIDITY LEVEL TARGET
ROOF ICE DAM LEAKS
INSECT INFESTATION / DAMAGE
INSULATION IDENTIFICATION GUIDE
INSULATION INSPECTION & IMPROVEMENT
LEAD POISONING HAZARDS GUIDE
LEAKY ROOF DIAGNOSIS & REPAIR
LEED GREEN BUILDING CERTIFICATION
LOW SLOPE ROOFING
MASONITE WOODRUF FIBERBOARD ROOFING
MEMBRANE & SINGLE PLY ROOFS
MODIFIED BITUMEN ROOFING
NOISE / SOUND DIAGNOSIS & CURE
NOISE CONTROL for ROOFS
PLASTIC ROOFING TYPES
PVC, EPDM, RUBBER ROOFING
ROLL ROOFING, ASPHALT
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF DORMER TYPES - PHOTO GUIDE
ROOF INSPECTION SAFETY & LIMITS
ROOF JOB PROBLEMS, RESOLVING
ROOF LEAK DIAGNOSIS & REPAIR
ROOF NOISE TRANSMISSION
ROOF REPLACEMENT SNAFUs
ROOF SLOPE DEFINITIONS
ROOF VENTILATION SPECIFICATIONS
ROOFING FELT UNDERLAYMENT REQUIREMENTS
ROOFING MATERIALS, Age, Types
ROOFING TILE SHAPES & PROFILES
ROOFING UNDERLAYMENT BEST PRACTICES
RUBBER, EPDM, PVC ROOFING
SADDLE CONSTRUCTION at CHIMNEYS
SIDING TYPES, INSTALLATION, DEFECTS
SLATE ROOF INSPECTION & REPAIR
SLATE ROOF REPAIRS
SNOW GUARDS & SNOW BRAKES
SOUND CONTROL in buildings
STAIN & BIODETERIORATION AGENT CATALOG
STAINS on & in BUILDINGS, CAUSES & CURES
STAINS on CONCRETE
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
STAIN DIAGNOSIS on ROOFS
STAINS on STONE, DIAGNOSE & CURE
STANDARDS for ROOFING
STONE SURFACE CLEANING METHODS
STRESS SKIN INSULATED PANELS
TEST LABS - ROOF SHINGLE
THERMAL EXPANSION CRACKS in BRICK
THERMAL EXPANSION of HOT WATER
THERMAL EXPANSION of MATERIALS
THERMAL IMAGING, THERMOGRAPHY
THERMAL IMAGING MOLD SCANS
THERMAL MASS in BUILDINGS
TRUSS UPLIFT, ROOF
TRUSSES, FLOOR & ROOF
UNDERLAYMENT REQUIREMENTS on ROOFS
WALK-ON ROOF SURFACES
WARRANTIES for ROOF SHINGLES
WIND DAMAGE to ROOFS
WOOD SHAKE & SHINGLE ROOFING
WORKMANSHIP & ROOF DAMAGE
ZINC METAL ROOFING
Guide to asbestos cement corrugated roofing:
This article provides a photo guide and text that can identify the condition of cement asbestos roofing products like asbestos-cement roof shingles.
We discuss how to identify corrugated cement asbestos roofing and how to treat this material when found on a building.
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Asbestos cement roof shingles were in popular use in the U.S. from the 1920's (est) through the 1960's (est) and were sold in the U.S. into the 1970's and according to some sources even in the 1980's.
The mixture of asbestos fibers and portland cement to form a hard material that was was durable and fire resistant is credited to Ludwig Hatschek who, in 1900, came up with the name Eternit associated with a U.S. producer of these products.
[Click to enlarge any image]
Large Asbestos-Cement Sheet Goods Production
Amy Lamb Woods, in "Keeping a Lid On It" Asbestos-Cement Building Materials" provides a superb and concise description of the history and properties of asbestos cement building products, while beginning at ASBESTOS ORIGIN & NATURE we provide the compete text of Rosato's 1959 seminal work on this topic. The following excerpts are from Woods (2000):
The Hatschek machine made possible the production of large asbestos-cement sheet goods. See CEMENT ASBESTOS PRODUCT MANUFACTURE for details of the Hatschek machine and its operation.
The typical life expectancy of an cement asbestos shingle roof was given as 30 years, But we have seen these roofs that were now 50 years old in good condition. Typical roof wear or failure patterns are either failure of the shingle fasteners or broken and falling shingles.
Virtually all of the asbestos cement roof shingle inspection points, installation limitations, and environmental concerns which we discussed at Guide to Cement-asbestos roof shingles also apply to corrugated asbestos-cement roofing products.
OPINION: The lichens growing on cement-asbestos roofing (photo at left), especially this thick corrugated material, is probably less of a wear concern than when that material appears on asphalt shingles or roll roofing.
Do not try to walk on this material without taking the same precautions as if accessing a slate roof: the material is easily damaged by foot traffic.
Watch out: As we discuss at POWER WASHING ROOFS we do not recommend power-washing asbestos-cement nor any other roofing.
However there are techniques for preventing or killing off algae growth that stains roof surfaces.
See BLACK ROOF STAIN REMOVAL & PREVENTION for advice on diagnosing, cleaning, and preventing stains on roofing.
Reader Question: What should I do about corrugated fiber cement roofing on my home - is it asbestos? Is it dangerous?
I just bought my house. It was inspected a friend who saw my roof, photos [above and below] and who says it is asbestos. Can you tell by looking at a photograph if this is an asbestos-cement roof ?
Reply: It depends ...
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem or that can more accurately estimate the age and thus the chances that your corrugated roof is an asbestos-containing product.
That said, here are some things to consider:
Those questions can also help answer your question about asbestos roofing.
What to do with this corrugated fiber cement or asbestos cement roof
[Click to enlarge any image]
According to NRCA, the National Roofing Contractors' Association, their studies up to February 1992 had not found a single roofing job at which these limits were exceeded, and NRCA reported that in some cases no fiber release was detected.
But it appears that the association may have been referring only to asphalt-based roofing materials, not jobs involving the demolition of other ACRM such as cement-asbestos roof shingles (or "asbestos roof tiles" as some consumers refer to them) which might produce different statistics.
and ASBESTOS REGULATION Update that address the handling of asbestos containing building materials, including ACM (asbestos containing materials), PACM (presumed asbestos containing materials), SACM (suspect asbestos containing materials), and ACRM (asbestos containing roofing materials).
Reader Question: what are the engineering properties of transite roof decking (cement asbestos roofing)?
I need to find the engineering properties of a specific profile of transite roof deck. Please see the attached sketch and picture. I will gladly purchase the correct catalog if you can help me identify which catalog that is. - Anon, 11/18/2014
For engineering properties of a contemporary material you'd find easiest results contacting the manufacturer. And Woods (2000) cites Hannant (1978) as a source for the engineering properties of various fiber cement roofing materials.
The original properties of corrugated cement roofing using asbestos, which you referred to as transite roofing, can also be found in some early patent applications, though I have not seen complete engineering analysis of the materials strengths and other properties in those documents.
For the engineering properties of an older asbestos-cement roofing product (which is what I think I see in your first photo above and again at left) that is of course no longer in production one might find an old specification document but in my OPINION that would be dangerously misleading as weathered, worn building materials change in properties such as density and impact resistance.
My experience with direct inspection as well as owner reports of older fiber cement and asbestos cement and corrugated asbestos cement is that the material becomes quite fragile - at that age its properties would be quite different from the original product specifications.
For that situation, if it were actually justified, one would have to send representative samples of the material to a materials testing laboratory - which of course raises its own issues about roof damage and material disturbance.
I notice in one of the links you provided that the life expectancy of cement asbestos shingles was given as 30 years with some 50 years old roofs in good condition.
The most detailed analysis of the engineering properties of Asbestos-Cement roof decking materials is the by el Hakim cited below. His conclusion begin on p. 280 of the thesis and are illuminating.
But again I emphasize that as with other building materials, after years of service the mechanical properties of asbestos cement are likely to be different than when first produced, more-so if exposed to the weather or to leaks and/or freeze-thaw cycles or to the effects of algae or cyanobacteria and of course if exposed to mechanical damage or stresses.
My own direct inspection as well as field anecdotal data show that the when exposed to the weather, more water and temperature variations than sunlight, asbestos cement products used on roofs tend to become soft and quite fragile. Effects of biological agents, particularly lichens, moss and to a degree, fungi also play a role in this deterioration.
Common Forms of Cement Asbestos Roof Wear & Deterioration
My opinion (I am not an engineer but have field experience and have done some research on the topic) is that if the corrugated asbestos-cement roof decks you describe have been protected from the weather (including leaks through the roof membrane) and thus from water and freeze-thaw cycle effects then the materials may be in better condition than the roofs I've inspected that have been directly exposed to the weather. Asbestos cement roof deterioration elements we expect to find in the field include:
Importance of Visual Assessment of Asbestos-Cement Roof Condition
However without lab testing combined with an intelligent assessment of the extent of roof area over which a particular form of deterioration is observed, in my opinion, a quantitative statement of roof life remaining would be unreliable. See Giller (1993) on visual assessment of roof decking.
A more detailed inspection of the asbestos-cement corrugated material-roofed building(s) you are evaluating is needed to determine the leak history as well as to find other instances of mechanical or other damage to the roofs. Certainly one of your photos shows one of the worst, most heaved, out of flat membrane roof surfaces I have seen. One might choose the most-suspect roof area for further, more invasive inspection or materials testing.
In my opinion, an astute roofer would be reluctant to accept a roof-over job on such a roof because of lack of confidence in the durability of that approach, or s/he would make clear in writing that there was little or now warranty on the roof job unless the new roof could be installed over an appropriately secure and smooth roof deck.
Also you may want to take a look at ASTM E2394 and at Oberta's proposed Standard for repair and maintenance of Asbestos-Cement materials.
Fiber cement roof life expectancy research & maintenance standards of interest:
References for the Properties of Corrugated Cement Roofing & Siding Products
In addition to the citations at REFERENCES
Other Research Citations on Asbestos Cement Roofing
Contemporary roofing product manufacturers make reinforced fiber-cement roofing shingles and other roofing products which look like, perform similarly to, and need to be installed similarly to the original corrugated asbestos-cement sheet roofing - but these new products are free of asbestos. (Photo at left: author points to new fiber cement roofing product.)
As we explained in our discussion of cement asbestos shingles, the replacements for corrugated asbestos cement roofing products are reinforced with a variety of fibers including fiberglass.
Other replacements for asbestos-cement roofing use both different fibers and a different aggregate (perlite) to replace the asbestos. Some of the substitute products have been in use for more than 30 years (2008).
Sources of modern fiber cement corrugated roofing (non-asbestos):
For handling and disposal guidance concerning old roofing material contact the US EPA, your state Department of Environmental Protection/Conservation, or your local building and health departments.
Continue reading at ASBESTOS ROOFING / SIDING DUST or select a topic from the More Reading links shown below.
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