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Fiber Cement Siding

Fiber Cement Siding

 

Fiber cement siding is most commonly seen as horizontal lap siding. It is also seen as vertical panels and as horizontal strips that simulate wood shingles. Finishes include smooth and textured patterns that simulate wood. Thickness is between 5/16 and ½ inch. It is installed by fastening siding to walls covered by a water-resistive barrier. Fiber cement siding has been available for about one hundred years. It was not until the mid-1980s that this siding became widely available in North America, and it has been increasingly popular since then. It is currently a widely installed wall covering. This siding is sometimes referred to by the brand name Hardie® after the company that first introduced it in the North American market. It is not correct to use brand names to describe materials. There are other fiber cement siding manufacturers.

Fiber cement siding should be installed according to manufacturer’s instructions. These instructions will vary based on the manufacturer, the model of siding being installed, and the location of the house.

Typical Defects Typical defects that home inspectors should report include:

  1. inadequate clearance above grade, hard surfaces, and roof coverings (1 or 2 inches above hard surfaces and above roof coverings, 6 inches above grade, all clearnaces per manufacturer’s instructions),
  2. absent and deteriorated flashing and sealant around doors, windows, and other penetrations,
  3. absent and deteriorated sealant at corner boards,
  4. absent movement gap (about ¼ inch) at vertical surfaces (e.g., corner boards, penetrations) and at horizontal flashing,
  5. absent blocks and head-flashing around wall penetrations such as exhaust duct terminations and hose bibbs,
  6. absent and improperly installed flashing and kick out flashing at wall intersections,
  7. damaged and deteriorated siding,
  8. improperly installed fasteners (e.g., wrong fastener type, improper location, over and under driven),
  9. excessively wavy or buckled siding,
  10. absent or deteriorated paint at the bottom edge.

 

Two diagrams side by side. Lefthand diagram depicts general siding nailing recommendations. Rightmost diagram depicts lap siding nailing methods.
 
Two side by side images. Caption reads "Fiber cement siding should have 1 or 2 inches clearance above hard surfaces and above roof coverings."
 
Two images side by side. Lefthand image caption reads "Wall penetration properly blocked and flashed (left) and improperly installed (right)." Rightmost image caption reads "Penetrations should not occur at joints. Hose bibbs should be blocked and flashed."
 
Image is captioned "Nails in wrong location. Siding may split."
 
Image caption reads "Buckled fiber cement siding. Possibly installed without movement gaps."
 
Image caption reads "Absent caulk at inside corner board. No movement gap (about 1/4 inch) at inside corner board."
 

StandardsStandards (1) IRC 2018 Section R703; (2) manufacturer’s instructions.