Thank you for your question on Hardiplank exteriors. There does not
appear to be a direct, scientific comparison between Hardiplank and
other exterior products, however, I have been able to unearth some
information that makes some comparison possible.
First, I'm sure you know a little about Hardiplanks, but here is some
basic information for completeness:
Hardiplanks are a type of fiber-reinforced cement, generally less
expensive than wood, made by James Hardie Building Materials, 26300 La
Alameda,Suite 250 Mission Viejo,CA 92691. Phone: 888-542-7343.
They are resistant to termites, fire, and high winds. The Hardiplanks
contain crystalline silica (35-45%), calcium silicate (50-60%),
cellulose (<10%), fillers (<10%). The primary danger of working with
Hardiplanks is the potential for inhalation of silica dust, which can
lead to silicosis, a potentially disabling lung disease, which can
progress to lung cancer. A complete MSDS safety sheet can be found
Proper installation of Hardiplanks includes the placement of a
weather-resistant barrier, as specified by the Uniform Building Code.
A general side-by-side comparison against vinyl, although perhaps
biased, can be found here:
A general comparison again wood-based siding can be found here:
Vinyl siding generally has a 20 year warranty, whereas Hardiplank
comes with a 50 year warranty. Wood-fiber composites such as
Wonderboard come with a 30 year warranty.
The main James Hardie site is here:
The Australian site can be found here, and has some additional information:
The company was originally founded in Australia and started off by
selling vinyl siding.
I was unable to locate any documentation of Hardiplanks having
increased degradation rates after breach of their exterior. In fact,
in the NER-405 report from the ICC Evaluation Service dated 4/1/2004,
the statement is made that one can blind nail Hardiplanks through
their top edge using corrosion-resistant nails, making the claim you
mention unlikely. Here is an excerpt from the report:
"When installed on wood-framing members, the siding shall be fastened
either through the overlapping planks (face nailed) or through the top
edge of single planks (blind nailed) with corrosion-resistant nails
into each wood-framing member from corners. Joints are fastened at
abutting sheet edges and optionally covered by polyvinyl chloride
(PVC) joint treatment, lumber battens or sealant. "
The full report can be found here:
Furthermore, it does not appear that Hardiplanks have any sort of
coating, etc., that may explain why they would degrade following a
breach of their exterior. A installation includes PrimePlus sealer
and primer, which acts as a primer and provides resistance to fungus
In terms of fire resistance, Hardiplank exteriors are superior. Here
are some examples from a case study:
"Firefighters Weigh In On Fire Resistance Of Exterior Sidings
(NAPS)?Real-world fire situations reveal fiber-cement exterior siding
to be more resistant to flames than other siding products, with
firefighters reporting it has barely singed in the hottest of blazes.
In St. Paul, Minn., a townhouse under construction caught fire,
producing one of the hottest fires firefighters there can remember.
The fire reached such proportions that two firetrucks sitting about 60
feet from the building caught fire, and trees across the street were
Lying undamaged within 10 feet of the destroyed building was a stack
of fiber-cement siding. A building about 50 feet away, on which the
siding had already been placed, also remained intact, aside from some
"We feel that the cement siding is probably what saved the structure,"
says Jack Hoffman, A-Shift deputy chief for the St. Paul Fire
Lt. Eric Jackson, public information officer for the DeKalb County
(Ga.) Fire and Rescue Services, says radiant heat generated from one
fire will often damage or set ablaze combustible material nearby.
Such was the case at a recent fire he helped extinguish at the Eagles
Run apartment complex in Atlanta. As one townhouse building burned,
the vinyl siding on the building next door literally melted off in
hunks, something Jackson says is common.
'Typically, if the fire is putting off quite a bit a radiant heat,
you'll start to see a melting effect,' he says. 'And then from that
point, if there is some flame contact, the vinyl siding will actually
catch on fire.'
For this reason, many communities refer to the Colorado State Forest
Service's list of recommended building products, which excludes vinyl.
Flagstaff, Ariz., is one, taking particular cautions against fires
because it is surrounded by the Coconino National Forest.
When a simulated wall was needed for testing the combustibility of
five decking materials, the Flagstaff Fire Department selected
fiber-cement siding for the exterior cladding of the wall. Three
composite decking products fared poorly in the test and caught fire,
explains Jim Wheeler, assistant fire chief. But the fiber-cement-sided
walls to which the decking materials were attached suffered only minor
singeing and discoloration.
'That's not from being in proximity to the fire,' he says. 'That's
from direct flame impingement. The fiber-cement siding did not allow
the passage of fire, and it did not break apart and fall away.'
Wheeler says he was not surprised the fiber-cement products held up
well. 'They are essentially a non-combustible product,' he says. 'They
have an inherent degree of fire resistiveness.'
According to Freddy Scharf, technical services manager for James
Hardie Building Products, 'The product is comprised of over 90 percent
cement and sand, giving it its fire-resistive properties.'"
Hardiplanks are also considered an environmentally friendly building
material. These advantages are summarized in this excerpt from the
Fiber Cement siding is a long lasting product. Made of all natural
materials such as premium cement, sand, natural fibers and water,
these materials are combined to create a superior siding product.
Unlike vinyl siding that is toxic to manufacture and difficult to
recycle, aluminum siding that is costly to manufacture and expensive
to mine, and wood siding that depletes our forest, our product
outperforms all these with a natural and long lasting alternative."
You can find an analysis of a Hardiplank Habitat for Humanity home's
energy cost and environmental impact, performed by the University of
Illinois, at this site:
Another story, from Health Building Network, can be found here
A comparison of Handiplanks with other materials was performed by the
University of Florida Center for Construction and Environment, and can
be found here:
Although it's perhaps a biased source, the following real-life
comparison from a special advertising section of Builder Magazine is
quite remarkable, particularly given your proposed application:
"The most destructive of hurricanes in 1999, Floyd wreaked havoc last
Deptember throughout the Bahamas and areas lining the Eastern
Seaboard. After it passed, John Head, owner of the Atlanta-based
construction company, as well as The Abaco Inn in the Bahamas, sent
Laney down to assess teh hotel's damage. The results were
astonishing. Hardiplank, the exterior siding use don the resort's
four newest building, were still intact. However, the cedar shingles
that had been used on the 13 other buildings were completely
'Three quarters of the cedar shingles had been blown away entirely,
and those tha tremained looked as if someone had taken a sandblaster
to them,' says Laney. 'The four structures that had been sided with
Hardiplank, however, were completely unscathed and didn't even need to
be repainted. In fact, the lap siding looked so clean that one would
think they had just been pressure washed.'
'After seeing how the two siding products performed side by side under
extreme conditions, there was no competition,' says Laney. 'The James
Hardie siding clearly held up better, so within weeks, we installed
Hardiplank on all of the buildings in the resort.'"
James Hardie Siding Stands Firm Against Mother nature.
Builder, March 2000, v23 i3 pS-5 .
The full text can be read here:
Another example, from the same reference as above, is equally impressive:
"Two families, from Reading and Andover, Mass., can also attest to how
well their new Hardiplank-clad second home in the Bahamas survived the
hurricane despite being right in the path of destruction. Russell and
Carolyn Kaplan and Randall and Jackie Peffer were building the house
on Great Guana Cay Island to serve as both a family vacation home and
a rental property. Just when construction was nearing completion,
Hurricane Floyd descended upon the small, beautiful island inhabited
by a mere 150 people.
'It looked like a bomb hit right around the house after the hurricane
had passed,' explains Kaplan. 'There was debris everywhere and hardly
a leaf left on any tree. Yet our Hardiplank siding remained in
Kaplan says that as a real estate agent, he often mentions the story
about how the beach house, which they named Blue Coral Landing,
withstood the wrath of Floyd. In addition to touting the lap siding's
ability to withstand hurricane-force winds, he also tells clients
about its authentic wood appearance and resistance to termites.
'My builder, Bruce McDaniel, who manages the nearby Dolphin Beach
Resort, suggested we use Hardiplank siding on the house and for that,
I'm very thankful,' adds Kaplan.
McDaniel, who has been in the building industry for more than 15
years, says he has worked with a great deal of siding products and
knew James Hardie siding would be the best one for Kaplan to use,
partially because it can be installed to withstand hurricane-force
winds up to 130 miles per hour."
More information from the above source:
"In a survey of U.S. builders, Hardiplank siding was rated as the
highest-quality lap siding product over the past two years. It has
been sold throughout the United States for 10 years, and has been
installed on over 1 million homes nationwide. James Hardie siding
products were also featured on several idea homes last year, including
the 1999 Southern Living Pine Glen Idea House in Village of Pinehurst,
N.C., Coastal Living's 1999 Idea House in Carillon Beach, Fla.,
Sunset's 1999 Ranch House of the New Millennium in Newport Beach,
Calif., and Better Homes and Gardens' Blueprint 2000 house in Chapel
Hill, N.C. "
An earlier article in Chilton's Hardware Age includes a discussion
with Dale Brannock about non-wood lumber alternatives for building.
Here is the reference:
Chilton's Hardware Age, Sept 1995 v232 n9 p47(2)
The abstract for the interview sums up Mr. Brannock's views:
"There are viable alternative building materials available in the
current market, according to Pelican Co's Dale Brannock. Products that
Brannock believes show strong promise include a cement-fiber siding
product called Hardiplank. Brannock believes steel, engineered woods
and glulam are also good products for construction projects. However,
he does not believe that vinyl siding is a good material because it is
not strong enough to withstand heavy storms."
One issue that has been of concern in the use of Hardiplank is the
risk of moisture accumulation within the wall. The National Research
Council in Canada addressed this issue in their analysis of
Hardiplank, stating that
"The possibility of moisture accumulation within the wall construction
is mainly a function of the level of workmanship related to the
elements constituting the second line of defence such as wall
sheathing membrane, flashing, caulking and attachment of siding. A
high level of quality control at all stages of the exterior wall
construction is imperative for obtaining an acceptable performance."
The full report can be found here:
The James Hardie website provides links to some technical data here:
Hardiplank exteriors have been used in several recent Extreme Makeover
Home Edition remodels. Before and after photos can be found here:
Some other exteriors can be found here, but without any "before and
Here is the (brief) About.com page about Hardiplank, compiled by Jackie Craven:
You can find images of the various types of Hardiplank available, as
well as thickness, weight, length, and other data at this page:
Overall, my research indicated that Hardiplanks are an excellent
choice for demanding, damp environments, including the one you
I hope this information was helpful. Feel free to request any
clarification. Best of luck with your remodeling.