Fiber cement siding knot pattern aids in product manufacturer identification (C) 2013 InspectAPedia Daniel FriedmanHow to Identify the Brand of Fiber Cement Siding
Photos, markings, dimensions, profiles, characteristic knots or fingerprints of FC siding

  • SIDING, FIBER CEMENT IDENTIFICATION - CONTENTS: how to identify fiber cement lap siding & other siding products using photographs, measurements, product stampings, markings, & dimensions
  • POST a QUESTION or READ FAQs about about the identification procedure for fiber cement siding products such as CertainTeed Weatherboard, James Hardie's HardiePlank, & other manufacturers of fiber cement lap siding.
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Fiber cement siding identification photos & markings: here we explain how to identify the manufacturer, brand, or type of fiber cement siding installed on a building.

This article describes the characteristic embossed fingerprints of woodgrain or knots on some fiber cement siding products, the markings and stampings on others, and the dimensions or details on still others, all of which can help make a reliable identification ofjust what fiber cement siding product is installed.

We also summarize the differences among manufactured "lookalike" siding products such as asbestos cement siding, fiber cement siding, and hardboard siding - differences that can be confusing to many people.

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How to Identify Fiber Cement Siding Products, Brands, Labels

Marie Carr provided photograph at below left along the product's identification from construction records. The siding finish concern is discussed at

Photograph of deteriorated James Hardiplank hardboard siding. Gaps at vertical trim joints of HardiePlank siding (C) Daniel Friedman

Article Contents

Make Sure You Have Correctly Identified the Siding Material and Brand

Watch out: informal surveys we performed in 2012 and 2013 in which we reviewed the top 20 website discussing fiber cement siding failures or performance issues we found a lot of confusion: hardboard siding was mistaken for fiber cemetn siding, and people were also inclinied to assign a manufacturer's name to a product before it was positively identified.

On some of our own field investigations of siding installations in that same period we found that onsite "experts", even manufacturer's representatives were not much more helpful. Too oftne the onsite consultant confined himself to simply stating "that's not our product".

Note: James HardiePlank™cement board siding is a cementious product that has been installed on more than 5 million homes.[10] This material is NOT the same composition as hardboard siding products sold by Abatibi Corp, Masonite Corp., Boise Cascade, and Georgia Pacific Corp, all of which experience failures of delamination, swelling, softening, and general deterioration when exposed to water and weather, depending on the quality of installation, exterior coatings, and maintenance. (Also see SIDING, ASBESTOS CEMENT).

Below we illustrate a loose fiber cement siding problem discussed at SIDING, FIBER CEMENT DEFECTS

Loose HardiePlannk siding at gable end cuts (C) Daniel Friedman

Unfortunately more nailing defects were apparent at the gable ends of the home where the lap siding abutted (or was supposed to abut) the gable end trim.

Left un-nailed the corners of most of these siding boards were curling away from the building. .

Consistent with our earlier warning that one bad turn suggests more are in store, even in a casual inspection we noticed other disappointing details on this home that was less than ten years old:

How to Identify Brands of Fiber Cement Siding Products: Certainteed, JamesHardie, others.

Edge dimensions & profile of fiber cement siding (C) 2013 Daniel Friedman Edge dimensions & profile of fiber cement siding (C) 2013 Daniel Friedman

Unidentified Fiber Cement Siding Photos

At above right and again at below right is a photograph of a knot embossed in the siding at the home that whose fiber cement siding installation is illustrated beginning at SIDING, FIBER CEMENT DEFECTS. Comparing the characteristic wood grain "knot" pattern in our "unknown" brand siding (above right and below right) suggests that while the unknown product is not a CertainTeed siding product, it may be an imitation or effort at copying the CertainTeed marking shown at below left.

This siding was back primed but included no numbers or markings on its reverse side, of dimensions 8 1/4" wide by 9/32" thick with squared edges.

That detail rules out HardiePlank® as you'll read below. Our knot comparison, given next, seems to rule out Weatherboard.™

Identifying Details for CertainTeed® WeatherBoard™ fiber cement siding

At below left is a characteristic knot ID pattern from CertainTeed Weatherboard™ - on order to focus on the imprint pattern and not color, we shifted the hue to match that of the unidientifed product at below right. CertainTeed fiber cement lap siding will include an imprint on the reverse side, using numbers and letters including one of these three letter pairs: RR, TH or WC.

CertainTeed fiber cement siding identification photo (C) CertainTeed Corp - InspectApedia 2013 Fiber cement siding knot pattern aids in product manufacturer identification (C) 2013 InspectAPedia Daniel Friedman

More about identifying CertainTeed fiber cement siding is just below at CERTAINTEED WeatherBoards identification markings.

On 3/20/2013 we learned that James Hardie has now told the homeowner of the mystery siding that the siding on their home is not Hardieplank. It appears that the mystery siding is also not a CertainTeed product.

Site visits to collect siding samples and to review conditions at the building were made during 2012 and 2013. Conversation with a Chinese fiber cement siding manufacturer who had contacted us with the exciting news that they had now come back into posession of molds to create woodgrain product.

Several people asked if it were not possible to compare woodgrain patterns as an identifying fingerprint for fiber cement lap siding products, as has been the case with similar products in the past. Well yes, and perhaps no or maybe. First, not all fiber cement products rely on an identifying wood-grain pattern or knot. For example HardiePlank fiber cement siding illustrated below is identified by other markings both embossed as a nail line or in data stamps on the product back side.

How to Identify CertainTeed® WeatherBoards™ fiber cement siding

CertainTeed fiber cement siding identification photo (C) CertainTeed Corp - InspectApedia 2013All CertainTeed fiber cement products can be easily identified by one of two means, both of which are accepted by the company when processing product warranty claims: [5c]

  1. Product control and identification numbers imprinted on the reverse side of the fiber cement siding will always be present and will include one of these sets of initials:
    • TH (Terre Haute Plant)
    • WC (White City Plant)
    • RR (Roaring River Plant)
  2. Unique fingerprint of wood grain in fiber cement siding: CertainTeed WeatherBoards are imprinted with a wood grain pattern that includes a characteristic knot recognizable in photographs as well as in siding samples.

Other Certainteed Weatherboard siding observations & characteristics:

Certainteed® DuraPress® stamp on fiber cement siding back

DuraPress(R) trademark of Certainteed fiber cement siding ca 2001 - at

Comment: DuraPress stamp on siding back side

Don said:

The "Unidentified FC Siding" image above is the same as my house. On the back side, it is stamped DuraPress. I found a Contractor guide published by Certaineed in 2001 & 2002 which talks about DuraPress as part WeatherBoard line - Can anyone confirm this?


Don included a link to a Certainteed document describing Certainteed Weatherboards(TM) Fibercement siding. Certainteed produces Weatherboard fiber cement siding in various colors and designs including lap siding in four designs, vertical panel siding in stucco, smooth, grooved and un-grooved cedar, soffit coverings, and in the company's "Shapes siding" panels are provided in a several lap shingle designs.

Here is a copy of the Certainteed document providing various siding images that can aid in identification of these products:

Don is quite correct that the DuraPress® grain definition is a Certainteed registered trademark. DuraPress® is a proprietary manufacturing process using the company's DesignMold™ plates providing embossed patterns such as wood grain. So if you find a DuraPress® stamp on the back of your fiber cement siding product then it's a Certainteed siding material. Quoting the company's brochure cited above:

CertainTeed’s proprietary DuraPress® System of manufacturing gives WeatherBoards siding superior protection against the elements. And to further protect its beauty, WeatherBoards is available factory-sealed with the exclusive FiberTect™ Sealing System. Your home deserves the great looks and long-lasting durability of WeatherBoards siding, America’s finest fiber cement siding. - Op. Cit.

Watch out:however we included the two images above because of confusion about this characteristic knot mark in Certainteed siding. The right-hand image is very similar to the "official" Certainteed knot mark but is an obverse. Look with care when making these comparisons and if you like use the page top or bottom CONTACT link to send photos for comment.

Watch out: the same name DuraPress, a registered Certainteed trademark is also occupied as a .com website by a domain name squatter. Avoid that site.

Examples of Certainteed DuraPress® embossed fiber cement siding products

[Click to enlarge any image]

Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at

Above and just below: Certainteed DuraPress® fiber cement siding from a 2001 product brochure cited earlier.

Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at

Below: Certainteed Weatherboard® DuraPress® fiber cement siding in wood-like shingle patterns.

Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at


Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at

Below: Certainteed Weatherboard® DuraPress®-embossed fiber cement sheet siding in a stucco pattern.

Certainteed fiber cement lap siding - 2001 brochure - (C) Certainteed Corporation at

Certainteed Weatherboard Class Action Lawsuit Settlement Status

How to Identify James Hardie's HardiePlank® fiber cement siding

Look for the Nail Line on some HardiePlank® products

Our photo just below shows the nail line markings embossed into the upper edge of certain James Hardie HardiePlank® products. This marking was found on James Hardie's pre-finished Autumn Tan HZ5 Cedarmill Hardie ee fiber cement siding at the Galow Homes fiber cement replacement job we describe in this article series.

Nail line markings on HardiePlank fiber cement siding (C) James Hardie & Daniel Friedman

HardiePlank's hz5-canada brochure avilable from the company at also includes a product photo (adapted at beow left and quite a bit blurrier than our own image) suggesting that one can identify the product by the James Hardie imprint along the nail line (which in blind nailed lap siding should be covered by the overlap of the succeeding siding course). [12c]

HardiePlank nail line (C) JamesHardie.comAbout the nail line on Hardieplank® FC siding, the company warns:

HardiePlank® HZ5® lap siding is manufactured with a nail line that should be used as a guide for proper nail placement when blind nailing. This nail line should not be used as a lap line. [12c]

This means you won't see this line on installed siding jobs unless you remove a section of the material.

While we searched in vain for a unique identifying knot or imprint photo online and at the company's website, nevertheless the company provides indirect assistance: you can send siding photos to their warranty claim office [if you think it's a Hardie product], or you can start by noticing that James Hardie's fiber cement product should be easily recognizable by

Fiber Cement Lap Siding Top & Bottom Edge Profiles Aid in Product Identification

Our photographs just below illustrate the top and bottom edge profiles of Hardieplank®HZ5® lap siding fiber cement product. These pictures were taken of siding still placed flat on the delivery pallet, rotated to their "installed" position, so the edge bevel and bottom drip edge profile may not be in the "installed" position on the building.

Hardieplank HZ5 top edge profile (C) James Hardie & Daniel Friedman Hardieplank HZ5 top edge profile (C) James Hardie & Daniel Friedman

Additional Identifying Stamps on HardiePlank fiber cement siding back side

Our photographs below illustrate what are probably mill and lot identification stamps found on the back of some Hardieplank® HZ5® lap siding fiber cement boards.

Identifying back side stamps on Hardieplank fiber cement siding (C) Daniel Friedman Identifying back side stamps on Hardieplank fiber cement siding (C) Daniel Friedman

Identify other Brands of Fiber Cement Siding

How to Identify Fiber Cement Siding Produced in China

The illustration below is of a Chinese-made fiber cement siding product produced by Ningbo Yihe Greenboard Co., Ltd. While we have no specific complaint about this product, it and similar fiber-cement siding board products may add to difficulties in determining the origin and manufacture of various modern fiber-cement siding products.

Chinese made fiberr cement siding (C) InspectApedia

The siding above is described by the Zhejiang manufacturer as having hese dimensions:

Watch out: That fiber cement siding is available from a variety of sources is evident from the list given

Identification of Chinese-Made Fiber Cement siding may be aided by this additional detail offered by the manufacturer: beginning in 2012, fiber cement siding from the supplier listed above is provided only with a smooth finish. The embossed wood grain patterns that were used before 2012 have, according to the manufacturer "been mostly destroyed".

In the spring of 2013 the company contacted us with this update

While,unfortunately,since last year we had already stopped producing the Fiber Cement Siding Boards in wood-grain pattern.Because,most of the moulding plate that are used for wood-grain embossing were broken. And now,we can only produce common Fiber Cement Siding Boards without wood-grain embossing.

We have asked for identifying markings and a siding fingerpring.


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