Generic Systems


This section is designed to give our Maryland┬áconsumers the basic concepts of an average mitigation system. All systems must be designed specifically to each structure. Though the basic concepts are the same, what may work for your neighbor’s home might not work for yours.Radon Attic Fan


Originally, there were over 13 different types of radon mitigation systems. Over time and field tests, these choices have been narrowed down to about 4 different types of systems that are routinely installed. They are:

  • Sub Slab Suction System
  • Sub Membrane Suction System
  • Heat Recovery Ventilation System
  • Water System Mitigation


This is by far the most commonly installed system. It has a very high rate of success in dramatically reducing radon levels. The basic principle is to remove the air beneath the concrete slab. Since the radon gas gets into the home from the lowest level, by sucking out the underside of the slab you catch the problem prior to the levels of gas building up and entering the home. The best part is by removing the air from under the slab you do not effect the air in the basement that you either heated or cooled. Note: If you have a home that is a slab on grade this system applies to your home as well.


This is a system that is used should your home be built over a crawlspace. This can be either the entire home or just a portion of the home. ( If you are one of the lucky people who has concrete covering the floor in the crawlspace, this system does not apply to you .) The area of the crawlspace is either dirt or stone. Sometimes the builder will have spread out plastic to act as a vapor barrier. The problem is there is nothing to stop the flow of radon gas into your home. The plastic that is in the crawlspace is usually full of holes and does not reach the perimeter walls.

The way to mitigate the crawlspace is to first put a series of pipes down in the crawlspace that are perforated. Then we cover the area with 6 millimeter plastic, and finally, seal the plastic to the perimeter walls air tight. The concept is to create a membrane that traps the gas then the pipes can suck out the gas.


The system is installed only in very specific situations. It usually involves a very old home that has a root cellar. Usually the cellar has just dirt walls and a dirt floor. Since trying to seal the dirt is not practical, a special device called a Heat Recovery Ventilation box is installed.

The concept is to pull out fresh air from outside, blow it in the cellar and suck out the radon-laden air and blow it outside. The heat recovery comes from the act of blowing the cold fresh air over a section of pipes sucking out the radon-laden air. Since the air in the cellar is warmer then the outside air; as the cold air blows across the heated air it helps to warm up the fresh air coming in. Note: This is an expensive mitigation process. Usually extra insulation is needed to keep pipes from freezing. This system does increase heating bills.


This procedure removes radon from water. People who have wells have the potential to have a problem with radon in their water. This is not a large problem in the state, but can be a serious health risk if levels are too high. The systems installed are either aeration or granular activated carbon (GAC).

Aeration is the act of forcing air bubbles through the water to release the radon gas from the water molecule. The GAC system makes the water run through a special tank with activated charcoal that absorbs the radon. These systems are very expensive and need regular maintenance to keep them working properly.Waterborne Radon Reduction System