Sub-Membrane Depressurization Systems:
In crawlspaces that have dirt or gravel floors, we at RadoVent® seal your crawlspace with an airtight membrane called a vapor barrier. All stored items and debris must be removed from the ground prior to the installation of the crawlspace membrane. If there are sharp objects or sharp gravel we can install a layer of tar paper over the floor before placing the membrane. This helps prevent the plastic from being ripped or torn when placing storage items back in the area. We then install the vapor barrier which is a minimum 6 mil polyethylene, 6-12 mil cross laminate or 10 mil heavy duty vapor barrier. We secure the plastic membrane to the foundation alls or footings using wooden furring and concrete nails. Once the plastic is secured to the foundation walls the entire perimeter is sealed including any seams, splices and penetrations to create an air-tight barrier to block the radon gas. The radon mitigation system is then tied directly to the soil under the membrane. The system creates a twenty-four hour vacuum that constantly pulls the radon out to vent above the roof of the house.
Note: Some contractors install radon mitigation systems without sealing crawlspaces. Do not let this happen unless the crawlspace is inaccessible. A properly sealed crawlspace will further reduce radon levels, create a safer storage area and prevent energy loss. Make sure the method of securing the plastic is strong enough to last through periodic crawlspace entry such as: storing items, home repairs and utility workers. We care about the quality of your radon mitigation system and crawlspace membrane no matter who installs it. Please feel free to call us if you have any questions.
In crawlspaces that have concrete floors radon levels can be reduced by creating a vacuum in the soil under the concrete slab. Many concrete crawlspaces have a large amount of cracks. These cracks, along with the corner where the floor meets the foundation wall are sealed to create a more air tight barrier. The radon system is installed by drilling a hole through the concrete to access the soil underneath. The mitigation system creates a constant vacuum in this soil to vent the radon out above the roof of the house.
Many homes have a combination of crawlspaces, slab-on-grade areas and basements. These homes are treated using a radon mitigation system with several different suction points. A primary suction point is usually installed through the basement slab with auxiliary suction points installed to depressurize these crawlspace and slab-on-grade areas.
Crawlspace membranes are not known as a stand-alone method to significantly reduce radon levels. These should be installed in conjunction with the radon mitigation system.