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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.


Cemplank, Inc., Blandon, PA.

CertainTeed Corp., Valley Forge, PA.

Eternit Inc., Reading, PA.

James Hardie Co., Mission Viejo, CA.

MaxiTile, Inc., Carson, CA.

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 2009 International Builder Show in Las Vegas.

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  1. Jill Buffie | | #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. User avater 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. Jill Buffie | | #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.

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