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Green Basics

Fiber Cement

Fiber Cement Is a Durable Siding That Resembles Wood


A fire-resistant and durable siding

The rising cost and diminished quality of wood siding, along with its required maintenance, has broadened the appeal of fiber-cement siding, a mix of portland cement, sand, and cellulose fiber. The siding comes with warranties of up to 50 years. It won’t rot, split, or warp as wood siding can, and it’s noncombustible.


Less frequent paint jobs

Like wood, fiber cement must be painted, but because it shrinks and expands less than wood, fiber-cement siding holds paint longer, lowering maintenance costs. It is more expensive to buy and install than vinyl siding but less expensive than wood, stucco, or brick. It’s usually available with factory-applied primer or paint.

Fiber-cement siding is made by at least six manufacturers in the U.S., so pricing is competitive. Durability and cost make it a very attractive alternative to wood. Its main drawback from an environmental standpoint is the embodied energy in the portland cement, as well as the long shipping distances for some of the wood fiber. Some manufacturers now achieve a 30% substitution of fly ash for portland cement in their products, and some are working toward the use of only certified wood fiber.


Detailing the bottom of a vented rain screen wall is easy: use mesh to keep out insects. But how do you let the moisture escape at the top?

Mike Guertin demonstrates some nifty wall venting options including Home Slicker and DCI Cedar Vent, plastic strips that allow sideways air movement in addition to vertical.

This was shot at’s booth at the…

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  1. 8UsjWhQXFX | | #1

    Certainteed fiber cement siding
    I have read on the net that this company uses fly ash instead of silica in their siding and that it has been found to contain mercury and other toxic levels of heavy metals. Does anyone know if this is true?

  2. GBA Editor
    Martin Holladay | | #2

    Response to Jill Buffie
    CertainTeed does use fly ash for the manufacture of their fiber-cement siding. Most experts do not believe that the fly-ash content of the siding poses any risks to homeowners. However, if the fly-ash content bothers you, you may wish to purchase a different type of siding.

    Here is information from CertainTeed on your question:
    Use of Fly Ash in WeatherBoards Fiber Cement Siding.

  3. 8UsjWhQXFX | | #3

    ...I'm still on the fence. The experts also thought vermiculite was once a great option too and look how well that turned out.

  4. user-6758514 | | #4

    Links to manufacturers in this article seem to be obsolete. James Hardie is clearly still making fiber cement siding. Cemplank website is still out there, but contains many references to Hardie in its website; the other 3 either don't seem to offer fiber cement siding at this time (certainties) or the web addresses are for sale.

    Is Hardie now basically competition-free?

    1. GBA Editor
      Martin Holladay | | #5

      Good question! This article hasn't been updated for many years, and it is clearly time for an update. I invite GBA readers to respond.

  5. 7113044 | | #6

    I think this is pretty cool:

    1. GBA Editor
      Martin Holladay | | #7

      Wow, that fake cedar shingle product -- I assume it is some kind of panel -- looks terrible. What design genius thought it was a good idea to line up the gaps vertically? To anyone who has ever installed real shingles, this is frightening and ugly -- looks like a water leak, for sure.

      1. Expert Member
        MALCOLM TAYLOR | | #9

        An idiot must have installed that - and another photographed it for their site. It looks awful, but the pieces have a solid backing to overlap the shingle-y bits below so there should be no leaks.

  6. Expert Member

    I've used CertainTeed, Hardi and Allura, and with minor exceptions they appear to be interchangeable. Hardi seems easier to carry without breaking, but now has an up and a down side, which means you can't hide any dings in the edge by turning them over.

  7. 7113044 | | #10

    This is from the Allura website. I like the fiber cement siding that looks like real wood. Don't know if it comes like that or if you have to stain it, but I plan on using it on my project.

  8. bill328 | | #11

    most of the links no longer work

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