Fiber cement is a widely used exterior cladding due to its durability, stability, flame resistance, economics, and easy maintenance. Despite the benefits, fiber-reinforced cementitious products can be environmentally costly with energy intensive manufacturing that produces high levels of carbon dioxide.1
When choosing exterior cladding, it’s important to understand the product’s composition and its implications. Typically made of wood pulp and portland cement, fiber cement cladding can also contain silica and fly ash.2
Respirable crystalline silica, a known human carcinogen, is released when cutting fiber cement cladding. Enough inhalation of silica particulates can cause permanent lung scarring, lung cancer, and COPD.3
Fly ash particles are considered a respiratory irritant, triggering asthma, lung inflammation and immunological reactions. They are ultimately linked to cancer, respiratory diseases, heart disease, and stroke. 4 While the EPA has approved the use of fly ash in products when the substitution results in significant carbon reductions and environmental benefits, health advocates are promoting the precautionary principle as the pathways of potential toxic migration have not yet been fully explored. 5
Outside of those working directly with the raw material production, tradespeople and installers face highest levels of exposure, requiring protective gear from particle inhalation, special tools and well-ventilated spaces when working with the material.6
Proper installation is also important to reduce water infiltration and prevent moisture damage. Fiber cement is a porous material and is prone to water penetration. Moisture can cause the product to rot and harbor mold and mildew growth—causing health problems of its own.2
When considering fiber cement siding options, focus on closed loop manufacturing, chemical disclosure, and proper installation.
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