Blue-Green Algae and Its Effect on Fiber-Cement Roofing Within a Microclimate

May 15, 2002

By Colin Murphy, RRC, FRCI
4 • Interface January 2002
sRepresentative samples were collected from the Project site
and shipped to this firm’s laboratory in Seattle, Washington, for
testing and analysis. Additional testing of the shakes and the
“algae” growth was conducted by independent laboratories
in Seattle.
Testing revealed the bacterial growth sampled from the
Project primarily consisted of species of the cyanobacteria
• As further discussed below, the phyla of Cyanobacteria
(often generically named “blue-green algae”) are bacteria
that differ from all other forms of “algae” due to their
photoautotrophic nature – i.e., cyanobacteria, like green
plants, are capable of synthesizing their own food from
inorganic substances using light as an energy source.
• The Scytonema cyanobacteria are found from the Arctic
to the Antarctic, are common to Oahu and Maui1, and
“can commonly be mistaken for a fungus as it forms sootlike
specks, dark brown to black in color.”2
The investigation and testing confirmed the effect of this
cyanobacteria growth on the fiber-cement roofing is biodeterioration
of the cementitious elements. Due to the extent of the
observed growth and deterioration, the author recommends a
full examination of the suitability and long-term performance of
fiber-cement roofing elements in the Hawaiian market.
and its Effect on Fiber-cement
Roofing Within a Microclimate
An Investigation of Biodeterioration of Fiber-Cement Roofing
by Cyanobacteria and its Implications for the Roofing
Industry in Hawaii
By Colin Murphy, RRC, FRCI
The author was commissioned to conduct an investigation
on the island of Oahu at a major residential complex
re-roofed during 1993 to 1995 with fiber-cement “shake”
look-alike elements. The referenced “Project” consists of 82
wood-framed, two-story, residential townhomes constructed
in the early 1980s. The original roofing on all structures
consisted of red cedar medium shakes installed approximately
ten years prior to the re-roof. The fiber-cement shakes
were installed over the original “skip sheathing” and a 30#
organic underlayment. The conditions observed at the project
prompted the author to review other fiber-cement roof
installations throughout the island.
Inspections of fiber-cement roofing assemblies installed
throughout Oahu revealed very extensive areas of blackish
“algae” growth at all roofs. Only areas under cover (i.e.,
below overhangs and trees) were void of surface growth.
Photo 1 – Typical blackish algae growth observed throughout the
project complex .
January 2002 Interface • 5
The fiber-cement elements used in the roofing industry are
constructed from panels of fiber-reinforced cement. Proprietary
mixes of Portland cement, ground silica, cellulose fiber, and mineral
oxide pigments are built up in layers on rollers and then
cured by high-pressure steam autoclaving. The fiber-cement
product at all but two of the eleven Oahu projects visited was
positively identified to be from a single manufacturer.
• The product was marketed with a “50-year transferable
limited product warranty.”
• While there appears to be no formal withdrawal
of the product from the Hawaiian
roofing market, no evidence of current marketing
of the product can be found at the
manufacturer’s websites.
• Recently, the ICBO Evaluation Service
(“ICBO ES”) Evaluation Report supporting
the use of the product in model
building code jurisdictions has been
allowed to expire.3
Water absorption rates for fiber-cement materials
are naturally high, exceeding 25% on a dryweight
basis. Documentation submitted by a
primary manufacturer to ICBO ES in 1988 states:
“The … shakes demonstrated a water
absorptive rate of 27.7 percent of their
oven-dry weight. However, even with this
high water absorption rate, the average
weight of the … shake when installed as
described in the manufacturer’s installation
procedures is approximately 6 pounds per
square foot. This is well within allowable
weight limits and does not require special
structural supplementation.”
In a February 15, 1989 letter to the Metro Dade County
Building and Zoning Department (“MDCBZ”), a consultant to
the manufacturer wrote:
“Since this product is not classified as a ”Cement and
Clay Roof Tile,“ I do not believe that the water absorption
issue is relevant. What we want to get across is that the
product will perform the same function as the wood shake
and shingles.”
A similar letter, dated April 17, 1989, to the Product Control
Supervisor of the MDCBZ Department from
another consultant to the manufacturer, stated:
“As you are aware, it is not possible to
satisfy the water absorption requirements
of SFBC (South Florida Building Code)
under tiles for the subject roofing material.
To classify these materials as tiles or
shakes or shingles is also a question. In
my opinion, higher water absorption is
not a problem for the proper functioning
of these materials because the water
never leaks and is not detrimental to
the underlayment.”
Clearly, the focus of the efforts by the
manufacturer’s consultants regarding the high
water absorption/retention properties of the
fiber-cement product was to assure the Code
authorities that the retained moisture did not
add undue weight to the roof structure or pose
a deterioration risk to roofing substrates. No
review appears to have been conducted regarding
the potential for the retained water to foster
Photo 2 – Typical blackish algae growth observed throughout the biological growth in environments within the Code jurisdiction.
project complex
Photo 3 – Crumbling deterioration at leading edge
The findings of an ICBO ES Report issued in April 1988 stated,
“…the…Shake and…Slate Roof Systems described in this
report complies [sic] with the 1985 Uniform Building Code…”
Field observations confirmed the Project’s fiber-cement elements
were installed over a 30# felt underlayment applied to the
spaced “skip” sheathing substrate remaining after removal of an
original cedar shake assembly. The inspected attic voids were
hot. Minimal venting was observed at the roof eaves and field;
no power vents were installed. No ridge or gable venting was
observed. In general, the roof slopes are approximately 4:12,
although areas of lower and steeper slope were observed
throughout the complex.
The installation was found to be in general compliance with
the manufacturer’s published installation instructions. No fibercement
shake loss was observed as a result of “blow-offs.”
With varying degrees of severity, areas of blackish “algae”
growth on the shakes were observed throughout the Project
complex. At some localized
areas, e.g., under
eaves and at locations
swept clean by tree
branches, minimal algae
growth was observed on
the fiber-cement shakes.
Generally, inspection
revealed significant deterioration
of the shakes,
including cracking, crumbling and “leafing” at the leading edge,
and delamination of the fiber-cement layers.
Samples of the installed fiber-cement shakes were extracted
for testing. In addition, comparative samples of uninstalled
shakes, which had been stored onsite and protected from the
elements since the re-roofing installation, were secured.
Physical Property Testing
Physical property testing of the sampled fiber-cement shakes
was conducted at this firm’s laboratory in Seattle. Additional
testing and analysis of coating and core composition of the fibercement
elements were conducted by Analytical Chemistry, Inc.,
of Seattle. Testing and analysis of the sampled algae were conducted
by Lab/Cor, Inc., of Seattle. Visual inspection confirmed
the fiber-cement elements had varying concentrations of blackish
“algae” discoloration on the surface, except on those visuallyacceptable
samples that had been extracted from below eaves,
where the shake elements had been protected to some degree
from exposure to sun and water.
Cohesive failure (delamination) of the fiber-cement layers
was observed on some samples. In several cases, the extent of the
structural deterioration precluded testing of physical properties.
Testing for “flexural strength” per ASTM C-11854 standards
found a reduction in flexural strength performance (see Table 1)
6 • Interface January 2002
Photo 4 – Blackish algae growth begins below eave-protected,
shaded area
Photo 5 – Cohesive failure of the laminates
Table 1: Flexural Strength Test Results (psi)
January 2002 Interface • 7
for the exposed samples relative to the unexposed (“as new”)
samples taken from storage at the Project. Both the “as new” and
exposed samples met the minimum saturated modulus of rupture
(798 psi) set forth in ASTM C-1225.5
Specimens were selected from the Project sampling to represent
increasing degrees of severity of the blackened surface condition
and then tested for water absorption per ASTM C-1185
standards. An increase in water absorption corresponded with
the severity of the observed surface condition (see Table 2).
While the sporadic and low conditions produce results similar to
the “as-new” product, medium and high severity surface conditions
result in an increased water absorption condition.
Both exposed and unexposed shingle materials met ASTM
and ICBO requirements for watertightness, showing no signs of
droplet formation on the material underside.6
Coating and Core Composition
Representative specimens of the exposed and unexposed (i.e.,
the “as new” elements that had been stored under cover since
construction) fiber-cement shakes were tested for determination
of the surface coating and core composition and were examined
for the presence of algaecide. (Note the manufacturer’s published
literature does not state the fiber-cement shakes were manufactured
with an algaecide component.) The report issued by
Analytical Chemistry concludes:
• Unexposed samples are “a calcium-aluminum-silicate/
carbonate composite with a surface polymer coating.”
• The compositions of all “samples are similar except that
no polymer coating was detected on the surface of” the
sample that had been exposed to weathering.
• No evidence of the presence of algaecides, tin, arsenic, or
copper was detected on the unexposed samples.
“Algae” Testing
Testing by Lab/Cor identified the blackish algae growth as
primarily consisting of the cyanobacteria Scytonema sp., with secondary
growth of the Chroococus sp., Gloeocapsa sp., Aphanocapsa sp.,
and Oscillatoria sp., and chance traces of the single-celled green
alga Trebouxia sp. No significant algal or biological growth was
found on unexposed (below-eave) samples.
A loose fungal sample scraped from the leading edge of a
fiber-cement element was identified as lichen: composite organisms
comprised of a fungus and an alga living in symbiotic association.
The fungus absorbs water that is used by the alga in
photosynthesis; the alga synthesizes and excretes a specific carbohydrate
that the fungus can utilize as food.
• The algal component of the fungal symbiosis is usually a
single-celled green alga (Trebouxia, Coccomyxa) or a bluegreen
alga (Nostoc, Scytonema).
As noted above, the phyla of Cyanobacteria (often generically
named “blue-green algae”) is bacteria that differs from all other
forms of “algae” due to its photoautotrophic nature – i.e.,
cyanobacteria, like green plants, are capable of synthesizing
their own food from inorganic substances using light as an energy
source. Varieties of Cyanobacteria are observed in colorations
that range from pink to blue to yellow to black. Cyanobacteria
“are strikingly abundant in the humid tropics.”7
• “Blue-green algae also grow in profusion in the tropics,
frequently occurring on painted surfaces where they may
be so dark in colour [sic] as to appear almost black.
Scytonema is one of the commoner blue-greens on paint
and is easily mistaken for a fungus as it forms soot-like
specks, dark brown to black in colour. [sic]”8
• “Certain blue-green algae are also prevalent in tropical
conditions, and commonly occurring species belong to
Oscillatoria and Scytonema.”9
The Scytonema cyanobacteria are well documented as common
to Oahu and Maui. Much of the leading current research
efforts worldwide to derive potent anti-cancer drugs from the
Scytonema cyanobacteria are being conducted at the University
of Hawaii.
Generally, a regular supply of water is necessary for prolific
growth of cyanobacteria, and the synergistic effect of such
growth is to trap underlying moisture necessary for further growth.
• “The basic requirements for algal growth are a source of
inoculum, nutrients, oxygen, carbon dioxide, light, suitable
pH, and water, none of which is usually limiting.
Normally, only in the case of fresh concrete or asbestoscement,
is pH limiting; otherwise, it is water supply
which [sic] often offers scope for control.”10
• “Details of building design affecting the shedding of water
and minimizing its retention on critical building surfaces
are important because it is the duration of the period of
wetness that is crucial rather than the frequency of wetting
itself in predisposing a surface to colonization.”11
• “…the presence of extensive sheets of algal growth will
trap water and retard subsequent drying which [sic] in
turn will exacerbate water-induced damage of the underlying
Studies conducted on concrete high-rise buildings in
Singapore have found:
• “Algae are the first to appear on newly-completed building
surfaces. These organisms grow profusely on the
porous stonework and painted surfaces, especially where
the supply of moisture and light are not limiting. …These
growths contribute to the slow deterioration of the structures,
besides being aesthetically objectionable.”13
Studies have consistently found Scytonema on “stone, brick,
and concrete walls (often associated with buildings), paint and
limewash, roof tiles, and sandstone monuments.”14
Table 2: Water Absorption Test Results (%)
January 2002 Interface • 9
• Initially, “the surface of newly-prepared concrete or
asbestos-cement is a deterrent to algal growth because of
the high pH (often 11 or 12). The combined action of
water and the changing of the hydroxides to carbonates
results in the pH eventually falling sufficiently to allow
algal growth.”15
• “The ability of Scytonema and Calothrix to fix atmospheric
nitrogen is an added advantage for these two filamentous
blue-greens. Hence their high incidence of occurrences as
compared to the other filamentous blue-green algae.”16
Nitrogen fixation is a process whereby relatively inert dinitrogen
(~ 79% of the Earth’s atmospheric gas) is converted to
ammonia. Nitrogen fixation is a critical process for the nitrogen
cycle that supports life on our planet:
• Nitrogen cycle: nitrogen transformation from air and soil
(to) nitrogen-fixing bacteria (to) nitrifying bacteria (to)
plants (to) animals (to) decomposers (to) air and soil.
• “Multicellular life (plants, animals, and fungi) depend
almost entirely on bacteria to obtain (or ”fix”) nitrogen
from the air and transform it into a chemical form that
plants can use.”17
Some of the Cyanobacteria, including Scytonema, are key contributors
to the nitrogen fixation conversion of dinitrogen to
ammonia. The effects of this metabolic secretion of organic acid
on cement and concrete materials can be significant — “Algae
are considered corrosive.”18
In the presence of water, the ammonium resulting from the
nitrogen fixation process is oxidized by common nitrifying bacteria,
forming highly corrosive nitric acid, which can also interact
with “lime” (calcium oxide, a key component of Portland
cement) to form highly soluble ammonium sulphates that attack
the cement substrates via water migration. The higher the concentration
of sulphate in solution, the more serious the resulting
deterioration. The severity of the attack is increased if the sulphate-
bearing water is in continual contact with the substrates.
“Microbially-induced concrete corrosion” (aka “microbiologically-
induced corrosion”) has been extensively studied for the
pipeline and sewage treatment industries:
• “Microbially-induced Concrete Corrosion (MICC) is the
process where biogenic sulfuric acid reacts with cementitious
material to deteriorate the integrity of concrete pipe
and other structures.”19
• “Microbiologically-influenced corrosion or microbiologically-
induced corrosion (MIC) refers to corrosion and
ensuing loss of metal or concrete caused by biological
organisms. …MIC results from the corrosive secretions of
• “Although having an initial alkalinity as high as a pH of
13 due to the formation of lime in the hydration of dicalcium
and tricalcium silicates (Portland cement components),
concrete surfaces could have a pH as low as 0.6
because of microbiologically-induced attack. …The sulfuric
acid generated due to MIC directly attacks the underlying
substrate and causes destruction of the
For the fiber-cement shake elements, such attacks proceed
along the lines of cracks in the shakes and between the fibercement
layers, particularly when the movement of water is facilitated
by one-side water pressure or evaporation from a free surface.
Deterioration can occur from both crystallization and
chemical reaction. The result is disintegration, expansion, and
eventual delamination of the fiber-cement shingle.
In addition, the Scytonema cyanobacteria have filaments that
are surrounded by mucilaginous (moist and sticky) sheaths that
are negatively charged and hydrophilic. The sheaths absorb and
store water and associated nutrients during periods of rain and
from moisture found within the substrate. If the conditions (inorganic
nutrients, pH, UV, temperature, and water) are appropriate,
the filaments will grow, form new sheaths, and extend over
larger and deeper areas. The effects of the shrinking and swelling
of the hydrophilic sheaths during arid conditions and periods of
moisture intake will accelerate the biodeterioration process.
• “The presence of mucilage sheaths around cells and filaments
of blue-green algae probably assists them in the
colonization of such habitats. The sheaths retain moisture
and protect the cells from desiccation during periods of
drought. The dust retained by the sheaths provides nutrients
for the growth of the algae.”22
The report issued by Lab/Cor for the Project sampling states:
• “Scytonema sp. has grown into tufted masses over much of
the surface, and when these tufts are removed to expose
the underlying surface, filaments of algae can be seen
within the substrate below.”
• “Sand or quartz are seen lying freely amongst the filaments
of the organism. Presumably these grains originated
in the matrix of the …shake, and as the cement
deteriorated, these grains become disassociated from the
product matrix and become entangled with and adhered
to the gelatinous sheaths of the filaments of the growing
Scytonema sp.”
• “Also, an opaque, white deposit is commonly seen on the
surface of the Scytonema sp. tufts present on the deteriorated
product. These deposits likely are the result of chemi-
Photo 6 – Microscopic view of Scytonema Endolithicum – mucilaginous
sheaths cover the growing filaments (
cal altering of the cement matrix and the subsequent
redeposition of minerals originating
from the cement in the product.”
SEM (scanning electron microscope) images produced
by Lab-Cor23 dramatically depict the effects of
the expansion of these mucilaginous sheaths into the
fiber-cement elements. Photos 7, 8, and 9 provide comparisons
of a 150x cross-section of the surface of a
fiber-cement sample (from below an eave) without
algal growth and 100x and 1000x cross-sections of
the biodegraded surface of a sample colonized
by Scytonema.
In summary, Scytonema is feeding upon the rich,
moist fiber-cement matrix. Grains of fiber-cement are
continually being loosened from the substrate and
adhered to the sticky, slimy sheaths to provide essential
nutrients to the feeding cyanobacteria.
The resulting corrosive secretions work to loosen
more grains from the product matrix. The swelling
sheaths apply stress to the shake surface and core,
resulting in stratification and “leafing.”
The sampled shakes consist of fiber-cement
elements with an original polymer coating containing
no algaecides. The condition of the sampled shakes
varies significantly from as-new to extensive deterioration
and cohesive failure (delamination). The condition
has not yet compromised the overall integrity of
the water-shedding assembly except in limited areas of
significant degradation of individual fiber-cement
elements; however, the service life of the roofing system
has been compromised significantly.
The installed elements are colonized with species of the
filamentous cyanobacteria Scytonema that are common to
Hawaii and are known to grow prolifically in humid, tropical
climates. The extent of the colonization varies. Unexposed
shake materials and some areas of exposed shakes (e.g. at
eaves or at locations wind-swept by overhanging tree branches)
have no algae growth; however, most of the exposed
shakes have 100% colonization. The algae initially form in
Photo 7 – SEM image (original mag = x150) of cross-section of surface of
fiber-cement sample taken from under eave where no algal or bacterial colonization
had occurred
Photo 9 – SEM image (original mag = x1000) of cross-section of
surface of fiber-cement shake. Grains have “… become disassociated
from the product matrix and become entangled with and adhered to the
gelatinous sheaths of the filaments of the growing Scytonema sp.”
Photo 8 – SEM Image (original mag = x100) of cross-section of surface of fiber-cement
sample taken from area colonized by Scytonema
10 • Interface January 2002
January 2002 Interface • 11
the troughs of the irregular, three-dimensional surface and eventually
expand to cover the ridges.
As the Scytonema filaments grow, the mucilaginous outer
sheaths become increasingly entangled with and adhered to the
fiber-cement particulates, resulting in increased structural stresses
to the shake substrate. In addition, the hydrophilic sheaths
“shrink” when exposed to dry periods and re-expand when rewetted,
resulting in further internal stress within the surface of
the fiber-cement element.
Additional attacks on the structural integrity of the shakes
come from the corrosive effects of Syctonema’s production of
organic acid (ammonium) as it “fixes” atmospheric nitrogen. The
ammonium is then oxidized by commonly present “nitrifying
bacteria,” forming highly corrosive nitric acid, which can also
interact with the lime component of the shake elements to form
highly soluble ammonium sulphates that can attack the fibercement
core via water migration.
Mechanical deterioration resulting from the movements of
the sheathed filaments is supplemented by corrosive deterioration
occurring from both crystallization and chemical reactions
related to ongoing transformations of the organic and inorganic
acids that are natural products of the nitrogen fixation process.
The result is disintegration, expansion, and eventual delamination
(leafing) of the fiber-cement elements.
As the original polymer coating is removed in areas of algae
growth, more of the fiber-cement substrate is exposed, allowing
increased moisture migration and water absorption, and deeper
penetration of the Scytonema filaments. Loss of the polymer coating,
either through the cyanobacterial attack or through other
mechanical means (e.g., power washing), is not the primary
cause of failure, but accelerates the condition. Use of an algaecide
in the polymer coating would have delayed but not prevented
the onset of the cyanobacterial growth.
Inspection revealed the installation of the fiber-cement product
to be generally compliant with the installation requirements
published by the manufacturer. There is no aspect of the application
that would have resulted in promoting the extensive proliferation
of Scytonema cyanobacteria.
Instead, the condition results from the natural phenomena of
biocorrosion and biodeterioration: the fiber-cement shakes werre
sold into a market where the physical properties of the cement
substrate, combined with appropriate levels of moisture, temperature
and pH, produced an excellent host for the proliferation of
the locally common Scytonema cyanobacteria.
Due to the extent of the observed growth and resulting deterioration,
the author recommends a full examination of the suitability
and long-term performance of fiber-cement roofing
elements in the Hawaiian market.
Written protocols for remediation of bacterial growth and
resultant biodeterioration on stone walls date back to early
human history. The Old Testament, for example, proscribes
removal and replacement of the affected areas:
“…if the disease is in the walls of the house with greenish
or reddish spots, and if it appears to be deeper than the
surface, then the priest shall go out of the house to the
door of the house, and shut up the house for seven days.
And the priest shall come again on the seventh day, and
look; and if the disease has spread in the walls of the
house, then the priest shall command that they take out
the stones in which is the disease and throw them into an
unclean place outside the city; and he shall cause the inside
of the house to be scraped round about, and the plaster
that they scrape off they shall pour into an unclean place
outside the city; then they shall take other stones and put
them in the place of those stones, and he shall take other
plaster and plaster the house.” – Leviticus 14:37-42 (KJV)
Remediation of the conditions observed in Hawaii may
require similar full removal and replacement of fiber-cement
roofing systems. ■
1. Eric B. Guinther, “List of Species from Aquatic
Environments (Brackish and Fresh Water) in the Hawaiian
2. C.E. Skinner, “The Role of Algae in the Deterioration of
Decorative and Marine Paints,” Proceedings of the XI
Congress of FATIPEC.
3. ICBO Evaluation Service is a subsidiary of the
International Conference of Building Officials,
4. ASTM C-1185-92, “Standard Test Methods for Sampling
and Testing Non-Asbestos Fiber-Cement Flat Sheets,
Roof and Siding Shakes, and Clapboards,” American
Society of Testing and Materials, July 1992.
5. ASTM C-1225-93, “Standard Specification for Non-
Asbestos Fiber-Cement Roofing Shakes, Shakes, and
Slates,” American Society of Testing and Materials,
June 1993.
6. Samples that had deteriorated to the point of significant
leafing and crumbling were not tested due to the
advanced state of deterioration.
7. D.M. John, “Algal Growths on Buildings: a General
Review and Methods of Treatment,” Biodeterioration
Abstracts, Vol. 2 No. 2., 1988.
8. Ibid.
9. C. Grant, “Fouling of Terrestrial Substrates by Algae and
Implications for Control,” International Biodeterioration
Bulletin, Autumn 1982.
10. Ibid.
11. Ibid.
12. Ibid.
13. Ibid.
14. John.
15. Ibid.
16. Ibid.
18. Y.C. Wee and K.B. Lee, “Proliferation of Algae on
Surfaces of Buildings in Singapore,” International
Biodeterioration Bulletin, Winter 1980.
19. Jeffrey Davis, Dana Nica, and Deborah Roberts,
“Modeling Microbially Induced Concrete Corrosion in
Sewers,” University of Houston,
20. Shiwei Guan, Ph.D., “Synergistic Protection Against
Microbiologically Influenced Corrosion Using A 100%
Solids Polyurethane Incorporated with Anti-Microbial
21. Ibid.
22. Grant.
23. Barbara Reine and Colin Murphy, “Characterization of
Biodegradation of Fiber Cement Shingles by Scytonema sp.
Using Optical and Scanning Electron Microscopy,”
Microscopy and Microanalysis 7 (Supplement 2: Proceedings), pgs.
472-473. 2001. Barbara Reine is a Lab/Cor mycologist.
This paper was presented by the authors at the annual
meeting of the Microscopy Society of America on August
6, 2001.
12 • Interface January 2002
Colin Murphy, RRC, FRCI, founded Trinity Group
Fastening Systems in 1981. In 1986, he established Trinity
Engineering, focusing primarily
on forensic analysis of roof systems,
materials analysis, laboratory
testing, and long-term analysis
of in-place roof systems. The
firm, formally known as Exterior
Research & Design, LLC, Trinity
Engineering, is based in Seattle,
WA. Colin joined RCI in 1986
and became an RRC in 1993. In
1996, he was honored with the
Richard Horowitz Award for
excellence in technical writing
for Interface. In 1998, RCI granted
Colin the Herbert Busching Jr.
Award for significant contributions to the general betterment
of the roof consulting industry. In 2001, he was made a Fellow
of RCI.
Michael F. Gibbons has been appointed as the head of a
Green Roof Task Group at ASTM to investigate the possibility
of creating a standard for green roof infrastructure in
the U.S. The Task Group was set up under the E06.71
Subcommittee on Sustainability in Buildings, formed
in 1946.
E-06 has approximately 850 members and currently has
jurisdiction over 170 standards. These standards play a preeminent
role in the building industry and address issues
relating to the performance of buildings, their elements,
components, and the description, measurement, prediction,
improvement, and management of the overall performance
of buildings and building-related facilities.
For more information on the task group, contact
Michael F. Gibbons at 972-960-8726 or
—Green Roof Infrastructure Monitor
There were about 30 roofers working on a building just
one block from the World Trade Center when the hijacked
planes crashed into the WTC on September 11. Employees of
Conco Roofing, Brooklyn, NY, were reroofing 90
West, a 25-story building designed by Cass Gilbert,
constructed in 1907 and designated as an historical
landmark. When the second plane hit the South Tower,
debris littered the roof of 90 West, and one worker was
struck on the arm by what was thought to be a part of
the plane. His injuries were not serious, and he has
since recovered. Following the collapse of the towers,
five floors of 90 west were damaged by fire. The building
itself had other structural damage from falling
debris, including the northwest corner parapet wall
being torn off. The roofers’ trucks were buried in
the rubble.
—Roofing Contractor
Roofers Too Close For
Comfort on Sept. 11