Use this CSI 3-part SimpleSpecs™ template to specify sheet gas retarders for controlling radon and methane gas migration. Including building structures through crawl spaces, slabs on grade, and basement walls and floors.
A gas retarder is a material placed under concrete slabs to inhibit the passage of gases, such as radon, through the slab. These materials are typically made of polyethylene or other types of plastic and are placed on top of the soil before the concrete is poured. They help to prevent the buildup of harmful gases in the living space above the slab.
Gas retarders are important because radon gas is a radioactive gas found in soil and rock formations. When it enters a building through the foundation, it can accumulate to levels that are dangerous to human health.
Long-term exposure to high levels of radon gas has been linked to lung cancer. By preventing the passage of radon gas through the slab, gas retarders can help to protect the health of the building’s occupants.
A gas retarder’s lifespan depends on the material’s quality, the conditions it is exposed to, and the level of maintenance it receives.
Generally, a well-maintained gas retarder made of high-quality materials can last for several decades. However, inspecting the gas retarder during installation for signs of damage and contamination and repairing or replacing it immediately is important.
To be effective, the gas retarder must be continuous, with joints sealed and the retarder sealed around all penetrations and at the perimeter.
Using the term gas barrier is discouraged since it is nearly impossible to construct an absolute barrier.
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