How To – Selecting And Installing Cement Fiberboard Siding

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    Cement Fiberboard siding is no real stranger in the manufacture of exterior sheathing for homes and businesses. The product dates back decades and may have got a bad name in the business due to the use of Asbestos products that are very similar but had to be discontinued and removed from homes because of associated health problems. The fact is back in the 1950’s – 60’s it seemed there was an abundance of asbestos in the building industry and general manufacturing. It seemed that almost every type of product had asbestos added to it as some type of filler or insulator.

    The new products do not have this problem and are generally made with a fiberglass matting for strength and cement body for durability.

    The only health concern that you are likely to read about concerns silica dust from cutting the product during installation. This should not be a great concern to a home owner and if you are installing the product a dust mask and maybe a wet saw used for tile cutting is all you will need to reduce the hazard. You can also use special sheers to cut the product and this may be available for free or rental when you purchase the material.

    If you will be cutting the material indoors then you should not use a circular saw with diamond blade. Cut the product outside or use sheers or score and snap.

    Use of Tivek or Tar Paper Backer

    Before you install the product it is important that you follow standard sheathing protection methods and install a water resistant barrier. Manufacturers will each have their own suggestion on which product is best in your location and for each specific application.

    Tivek fiber based rolls are an easy way to cover large sections of your home’s exterior sheathing quickly. The material comes in 9 foot wide rolls and a two person crew can cover an average single story home in about 4 hours.

    Offset Distances

    When installing Cement Fiberboard siding it is important to carefully read the offset distances suggested by the manufacturer. Unlike Vinyl Siding that can be applied almost butting to a window door or stair the distances are much larger and require approximately 2 inches of offset from any fixed object.

    Since the offset is a larger 2 inches you will need to use casing to cover the ends where visible and on areas that abut roof-lines special flashing will be necessary.

    Contact your manufacturer for specific finishing detail suggestions.

    Proper use of Fasteners

    Like traditional shingling and siding the placement of nails will be on the non exposed section of the material.  A minimum of 24 inches on center with a minimum non nail border of  1/2 inch from the top edge and 2 inches in from the corners.

    Gauges can be  used to support the piece of siding being installed allowing one person to perform the work.  Cement Fiberboard must be well supported while hanging because unlike vinyl or wood it can snap causing internal structural damage and reducing its life.

    Splices should be made over studs and a minimum distance of 48 inches must be kept between splices.

    Splices near windows and doors must be a minimum of one stud cavity or 24 inches.

    Nails are to be used and staples are not recommended.

    When spacing your fasteners you should verify spacing requirements for your application and for wind resistance in your specific area. Homes in high wind locations will require smaller spacing of fasteners and may require other sealants and caulking techniques to maintain performance.

    Color & Texture Selection

    Fiberboard siding can come in a variety of shapes and textures to simulate natural wood that has been painted.

    If the product you install does not have a precolored finish then you will need to paint it within 90 days if it is un-primed or 180 days if it has a primer finish. 100% acrylic finishes are required and stain should not be used on cement fiberboard.

    Caulking of all seams and cuts is required and these areas can be touched up with paint within the first 180 days with a color match paint once the caulk has had time to cure. Another option is tinted caulk which is an added expense but if supplied by the manufacture will make color matching much easier.

    Your color selection will be limited to approximately 15 factory colors and the material is made with the colorant mixed throughout the material. Similar to solid surface counter tops if there is an abrasion or small chip the color will be the same and repair or painting may not be immediately necessary.

    Durability and Life Expectancy

    Cement fiberboard siding is a durable product that should last for many years. Each manufacturer will have ratings depending on your location and some manufactures have actually gone an additional step to produce products for winter locations vs humid southern locations with different additives and processes that extend their life in each temperature zone.

    Just like Vinyl Siding you can expect repairs to be necessary over the life of the product and eventually it will be necessary to replace all of your siding due to deterioration. You should check your warranty and expect from 40 to 60 years of life depending on your specific home and location.


    Cost is always a big issue when selecting exterior siding. You can expect to pay more then you would for Vinyl but less then you would for other traditional siding such as Natural Wood, Brick or Stone.

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