Fiber cement siding installation defects: buckling, curling, gaps, leaks, loose boards (C) E.D. Fiber Cement Siding Board Defect Diagnostic Questions
Questions help diagnose the cause of fiber cement siding complaints

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Fiber cement siding defect diagnostic questions.

This article lists questions whose answers can help explain or diagnose the causes of complaints that might occur some installations of in fiber cement siding shingle & shake installations in North America, including fiber cement shingle shrinkage gaps at butt joints, cracks, breaks, and loose or buckling shakes.

These questions address common causes of open butt joint gaps, buckled siding, loose siding, nailing failures, moisture effects, and we include opinions, field observations, and research on the causes & effects of these conditions.

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Fiber Cement Siding Complaint Diagnostic Questions

Fiber cement siding stored exposed to rain (C) InspectApedia E.D. The following questions and comments about them may help diagnose the probable cause of a variety of fiber cement siding defects or complaints that range from cosmetic to more significant.

Note: the reader-comments appearing at points in this article were provided by a reader whose siding is further illustrated and discussed at SIDING, FIBER CEMENT SHINGLE-BOARD DEFECTS - Troubleshooting gaps, breaks, peeling, bowing, loose fiber cement siding: causes, remedies. Nichiha Fiber Cement products, performance & warranty field report.

  1. Weather during installation: What were the weather conditions during siding installation? Rain? Was the siding rained-on during storage.
  2. Product Storage: How was the siding stored on-site. Were some bundles of material stored or protected differently from others?

    [Click to enlarge any image]

    Different batches or bundles of materials may arrive in different conditions or may be affected differently by variations in exposure on-site during storage before use. We see this in a report of jobsite measurements of SIDING, FIBER CEMENT MOISTURE LEVELS where one bundle of siding arrived as a "partial pallet" that had been re-wrapped at the lumber yard while another full pallet was in the original factory shrink-wrap.

    The fiber cement siding company's installation instructions include

    Sierra Premium and NichiFrontier products MUST be kept dry, and stored in a covered area or covered with a tarp before installation.

    Moisture saturation before installation may result in shrinkage and board damage. Do not install saturated boards. All pre finished products are required to be stored in a covered area.

  3. Product Moisture Levels before installation: Did anyone look at the siding moisture content ever? If so, when? Before installation?

    Given my [DF] experience when calling other fiber cement siding manufacturers, we may have trouble obtaining an explicit, quantifiable or measurable definition of "saturated" boards.

    Reader reply: No one looked at moisture content as far as I know.

  4. Siding Workmanship: Who were the actual members of the siding installation crew, what was their level of expertise, and what level of expert supervision was provided at the start, during, and at the end of the siding job? Did different individuals or different crews work on different building areas using different installation details or methods that show up later?
  5. Fastening Hardware: Was some of the face nailing added later to try to address buckling? How many nails or screws are exposed? How many fasteners that are exposed damaged the face of the siding? What kind of nails were used to install the siding (or screws)?

    Reader reply: No one tried to correct buckling as far as I know.
  6. Installation effects: errors installation such as improper nailing too close to board edges, failure to nail butt joints over wall studs, omission of required flashings or sealants, or other errors or omissions that do not follow the product installation specifications can show up as product leaks, cosmetic defects or other issues during or after the siding has been installed.

    Also see Time or Construction Sequence Effects and Weather Effects discussed in this article.
  7. Service life effects: what events have happened over the life of the building that affect its condition, such as unusual storms, floods, plumbing backups, mechanical damage events, fires, etc.
  8. Site variables: what conditions at the building site might explain or contribute to variations in product performance on different sides of the building or different roof slopes. Included are prevailing sun, wind, or rain directions, the side of a building facing an ocean, the side of a building closest to a highway and similar conditions. Any of these can cause otherwise identical material to perform differently in different building areas.

    We would still expect site variables to pertain. Sun exposure on one side of a building ought to make the effects of installing wet materials show up sooner on that side.

    The same material in exactly the same condition installed on other building sides might dry more slowly, avoiding for example, moisture- differential-caused fiber cement siding curling. But other wet material effects, such as butt joint shrinkage gaps ultimately should be the similar, excluding thermal effects by themselves, provided that all of the building materials were themselves in uniform condition at the time of installation.
  9. Sheathing properties: What is the sheathing on the home under the siding: plywood or fiberboard or a mix? Nailing siding over fiberboard sheathed buildings and also missing the location of the wall studs can result in loose or buckling siding problems.

    Reader reply: Sheathing is plywood as far as I know.
  10. Time or Construction Sequence Effects: Just when a fiber cement siding cosmetic or other defect appears can suggest the underlying mechanism at work. And conversely, the type of siding defect or complaint can tell us which failure mechanism was probably at work: For example:

    • Shrinkage gaps at butt joints almost certainly occur because siding was installed wet or at high moisture content. The problem began at time of installation and should show up in the first year or less.
    • Curling or buckling siding at butt joints more likely occurs because siding has become wet through it's back side after installation, typically from moisture or water leaks into the wall structure.
    • Sequence of construction effects:

      We may see variations in building material performance that maps to when the material was installed or the sequence of installation. For example a bundle of damaged material may cluster or appear staggered in only certain building areas or on just certain sides of a structure. Weather during the installation can be important: installing in wet rainy weather or over wet building surfaces can be a problem in some siding or roofing jobs. Painting in sun or painting on wet surfaces is a similar problem case.

      What were the weather or other conditions at the time of construction that might have affected the product or its installation. For example, roofing with asphalt shingles in cold weather can explain ridge cap shingle cracking failures.

      Conditions at the time of a building product installation such as the installation of wet materials, on a wet building, or other weather factors while work was being performed; included as well are variations in building material as it arrived at the job site: differently-stored pallets or differently-wrapped shipments of materials exposed to rain, for example.

      Example: Extensive but hidden mold contamination found in a modular home was traced to the discovery that at the time of delivery segments of the modular home had been driven at highway speeds in a driving rain but the factory had neglected to wrap and protect the front or leading end of each segment against water penetration during delivery.
  11. Installation specifications followed? Did the installer obtain the manufacturer's installation specifications? Did anyone look at them? We provide links to the fiber cement company's website, contact information, and product installation instructions below.
  12. Weather exposure: how do the observed failures or complaints map on different sides or weather, wind, and sun exposures of the building. For example the sunny-side of the building, receiving more heat, may experience faster dryout of moist boards showing butt joint gaps before siding on other building sides.
  13. Maintenance: are there maintenance or other site features that impact the performance of the siding, for example improper handling of roof drainage, surface drainage, rain splash-up on siding.


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