Soil Gas Mat and Barriers

To view detail about a particular product, click the Part Number in the appropriate column. This opens a small product window with full product details.

Soil Gas Collector Matting (for new construction)

According to the U.S. EPA’s model standards for radon control systems in new house construction, a means for collecting soil gas should be installed beneath the slab. (see Publication EPA/402-k-01-002 Building Radon Out). This can be either 4 inches of washed aggregate or a mechanical collection system such as a buried perforated pipe or a permeable matting laid beneath the concrete. If aggregate is to be used, there is no need for this mat. However, in most parts of the country the importation of aggregate is expensive and can cause de-watering problems, while the concrete is curing. In this case, you can either use a fabric covered, perforated pipe that is trenched into the sub-slab area when the plumbing is installed, or you can lay a matting on top of the finished grade immediately before the slab is poured. More and more mitigators and builders are using Soil Gas Collector (SGC) matting because its installation does not entail any special coordination with the plumbers. Just lay it down around the inside of the foundation, secure it with spikes or landscaping staples, and pour the concrete.

SGC matting is superior to other mat systems because it comes with a fabric cloth completely around it. This feature eliminates the need to lay a plastic sheet on top of the matting to prevent the concrete from entering the matrix. Using plastic sheeting can cause concrete cracking due to differential de-watering. The full fabric design greatly enhances both the installation as well as the quality of the concrete slab. When SGC matting is installed below the slab, you’re providing an airspace that intercepts radon before it seeps into the basement, or through the slab. SGC matting also works well as a soil gas collector beneath the plastic in sub-membrane systems for crawl spaces.

WHY AND HOW IT WORKS: The matting is a 1 inch high by 12 inch wide matrix enveloped in a polyester filter fabric. 90% of the geomatrix is airspace, which means radon has room to move to the collection point. The matting can support concrete without compressing, yet it is lightweight enough for easy handling. It comes shipped in 100 ft bundles consisting of 2 lengths of 50 feet each, for easy handling and installation.

This system allows the radon to flow through the filter fabric and into the airspace. The airspace does not clog because the filter fabric restrains the underlying gravel and soil. The natural airflow through the SGC matting then channels the radon to the pipe connection. From there, the gas can be routed outdoors. If high radon levels persist, inline fans can easily be installed to create greater air flows.

To install the matting, it is laid in a continuous loop around the interior of the foundation. The mat comes in 50 foot lengths that can be overlapped and spliced to form a continuous air flow channel around the perimeter. Corners are handled similarly. The ease of cutting and fitting the matrix eliminates the need for expensive fittings, thereby reducing the overall cost of the system.

SOIL GAS T-RISER FOR SGC MATTING

Another key element of a soil gas collection system is attaching the 4 inch riser to the matting, such that an airflow restriction does not occur at this critical juncture. This soil gas T-Riser is unique because it has special ports, which allow each end of the SGC loop to enter the collection box without special connectors.

The SGC T-Riser also has an ABS riser attached to it, which extends above the top of the concrete floor. Note that the future pipe opening is sealed to prevent wet concrete from entering the collection box. After the concrete cures, a simple cut reveals the opening into which a 4 inch PVC pipe can be connected. This unique design allows for a clean and easy connection and prevents excessive air flow resistance.

The system of the SGC matting and T-Riser very effectively streamlines the installation process during new home construction. This is very important for builders who have tight time constraints when working with subcontractors. Two people can install 200 L.F. for a 2,000 sq.ft. basement in less than an hour. The savings in time and labor is significant.