Fiber Cement

Fiber Cement Is a Durable Siding That Resembles Wood

Bird's-Eye View

A rot-resistant siding

Fiber cement is made from portland cement, sand, and wood fibers. Some manufacturers substitute fly ashFine particulates consisting primarily of silica, alumina, and iron that are collected from flue gases during coal combustion. Flyash is employed as a substitute for some of the portland cement used in the making of concrete, producing a denser, stronger, and slower-setting material while eliminating a portion of the energy-intensive cement required. Energy that goes into making a product; includes energy required for growth, extraction, and transportation of the raw material as well as manufacture, packaging, and transportation of the finished product. Embodied energy is often used to measure ecological cost.. Its durability and the ability to hold paint much longer than wood siding may offset this less green quality.

Fiber-cement siding is hard and impact-resistant, unlike vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). siding, which feels flimsy by comparison.

See below for:
LESS FREQUENT PAINT JOBS


Key Materials

Lap siding, panel siding, shingles

Most fiber-cement siding products are manufactured to mimic traditional wood siding types. The most common types are lap siding and panel siding. Some panel siding is configured to look like shingle siding.


Design Notes

Is it green?

Smooth fiber-cement shingles or planks make good substitute for traditional wood siding styles. Large panels are more likely to show up on a contemporary home (or be used with applied strips to simulate board and batten). The large panels with flashed or lapped joints can create more continuous surfaces and be cut into interesting shapes.

Portland cement is one of the primary ingredients in fiber-cement products. The resulting embodied energyEnergy that goes into making a product; includes energy required for growth, extraction, and transportation of the raw material as well as manufacture, packaging, and transportation of the finished product. Embodied energy is often used to measure ecological cost. makes the sustainability of this type of siding questionable. But its rot resistance and ability to hold paint longer than many alternatives are good reasons not to scratch it off your list.

Advanced framingHouse-framing techniques in which lumber use is optimized, saving material and improving the energy performance of the building envelope. note: Some fiber-cement siding products may deflect if installed on studs spaced at 24-inch centers. Check with the product manufacturer. You may also want to have a sample wall section built to check the appearance.


Builder Tips

Use special saw blades

A number of circular-saw blades are made specifically for working with fiber cement. According to manufacturers, these blades outlast carbide-tipped blades about 150 times over. Each blade has four, six, or eight polycrystalline diamond teeth, which are made by bonding a layer of tiny, tough-wearing diamonds onto an easily welded carbide substrate.

They come in sizes of 7 1⁄4-inch diameter for circular saws and 10-in. or 12-in. diameter for miter saws. The lower tooth count and deep gullets on these blades allow them to take out larger pieces of material rather than kicking up fine dust.

If you’re set on using a saw for cutting fiber cement, you should use these blades.


The Code

The code

The International Residential Code (IRCInternational Residential Code. The one- and two-family dwelling model building code copyrighted by the International Code Council. The IRC is meant to be a stand-alone code compatible with the three national building codes—the Building Officials and Code Administrators (BOCA) National code, the Southern Building Code Congress International (SBCCI) code and the International Conference of Building Officials (ICBO) code.) includes requirements for fiber-cement siding installations in Section R703.10. Among the provisions of this section is a requirement that vertical seams of panel siding occur over studs. All horizontal joints in panel siding must occur over blocking and must be flashed with Z-flashing.

Section R703.10.2 requires fiber-cement lap siding to be installed with a minimum overlap of 1 1/4 inch. Lap siding also "shall have the ends sealed with caulking, covered with an H-section joint cover, or located over a strip of flashing."

OTHER CONSIDERATIONS

Watch out for silicosis
Prolonged exposure to the silica dust generated by cutting fiber-cement products can lead to the most common occupational lung disease in the world: silicosis. When silica dust particles become airborne, they are easily inhaled and become deeply embedded in the lungs, where they cannot be cleared by coughing. Although many of the tools used to cut fiber-cement products do not produce much dust, it’s still a good idea to have a properly fitting respirator on hand. Make sure to choose an N95 NIOSH-certified respirator if dust is likely to become airborne.

DRAWING LIBRARY CONSTRUCTION DETAILS

Wall-section Details
Roof/Wall Details
Siding Details in Plan View

GREEN POINTS

LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. -H MR2.2 (Materials & Resources) offers 1/2 point for environmentally preferable siding, including FSCNonprofit organization that promotes forestry practices that are sustainable from environmental and social standpoints; FSC certification on a wood product is an indicator that the wood came from a well-managed forest., salvaged, and recycled-content options; 1/2 point more if it is locally sourced.

NGBSNational Green Building Standard Based on the NAHB Model Green Home Building Guidelines and passed through ANSI. This standard can be applied to both new homes, remodeling projects, and additions. Under Chapter 6, "Resource Efficiency": 1 point if sufficient wood content comes from certified source (606.1) and 1 point if sufficient substitution of fly ashFine particulates consisting primarily of silica, alumina, and iron that are collected from flue gases during coal combustion. Flyash is employed as a substitute for some of the portland cement used in the making of concrete, producing a denser, stronger, and slower-setting material while eliminating a portion of the energy-intensive cement required. 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 vinylCommon term for polyvinyl chloride (PVC). In chemistry, vinyl refers to a carbon-and-hydrogen group (H2C=CH–) that attaches to another functional group, such as chlorine (vinyl chloride) or acetate (vinyl acetate). 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 energyEnergy that goes into making a product; includes energy required for growth, extraction, and transportation of the raw material as well as manufacture, packaging, and transportation of the finished product. Embodied energy is often used to measure ecological cost. 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 ashFine particulates consisting primarily of silica, alumina, and iron that are collected from flue gases during coal combustion. Flyash is employed as a substitute for some of the portland cement used in the making of concrete, producing a denser, stronger, and slower-setting material while eliminating a portion of the energy-intensive cement required. Cemplank, Inc., Blandon, PA.
CertainTeed Corp., Valley Forge, PA.
Eternit Inc., Reading, PA.
James Hardie Co., Mission Viejo, CA.
MaxiTile, Inc., Carson, CA.

DETAILING A VENTED RAIN SCREEN

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 GreenBuildingAdvbisor.com's booth at the 2009 International Builder Show in Las Vegas.


Image Credits:

  1. Charles Bickford / Fine Homebuilding #163
  2. Krysta S. Doerfler/Fine Homebuilding #197
  3. Brian Pontolilo/Fine Homebuilding #187
  4. Krysta S. Doerfler/Fine Homebuilding #193
Tags: , , ,
3.
Aug 5, 2011 9:29 PM ET

Hmmm
by Jill Buffie

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


2.
Aug 4, 2011 6:34 AM ET

Edited Aug 4, 2011 6:35 AM ET.

Response to Jill Buffie
by Martin Holladay, GBA Advisor

Jill,
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.


1.
Aug 3, 2011 10:12 PM ET

Certainteed fiber cement siding
by Jill Buffie

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?


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