My new home came with a passive radon system. Isn’t that good enough? The short answer: no. The long one: even a perfectly constructed passive radon system will not necessarily reduce radon levels below the EPA’s action level of 4 pCi/l. This doesn’t mean your home wasn’t built well. It just means that the strength of the radon emanating from the ground into the house is stronger than your passive radon system.
What is a Passive Radon System?
Passive radon systems usually consist of a 3 or 4 inch PVC vent pipe that is sealed into the gravel layer under the basement slab or into a sealed sump cover which runs from the basement up through the home, into the attic and venting through the roof. The theory of a passive system is based on thermal stack effect, which causes a house to act as a vacuum on the soil due to temperature differences inside and outside the home.
Why isn’t my Passive Radon System Good Enough?
Radon is slightly heavier than air. Because of this, it generally won’t go up the vent pipe (which is a big component of your passive radon system) on its own. To draw the radon out of your home, you need to have a radon fan installed on the vent pipe inside of your attic in order to effectively reduce the radon levels in your home.
Sometimes in new construction, the passive radon system’s vent pipes are obstructed when they are set in the slab, rather than in the sump cover. It may be stuck too far into the dirt below the gravel, the gravel may be too compacted, the gravel is too small with too much dirt and sand in it are all things that make it difficult to create good air flow, or a vacuum, across the entire slab. When this happens, we have to re-configure the vent pipe to have a new slab penetration, creating enough open air space beneath it in order to be able to guarantee results.
What is the ideal setup for my Passive Radon System?
A passive radon system’s vent pipe should ideally be run through one of the combustion appliance chases (furnace or hot water heater) that run from the basement to the attic of a house. The heat inside these chases may create a vacuum in the vent pipe, but ONLY if the following conditions exist:
- The floor-to-wall joint and all other basement slab openings, such as sump crocks are completely sealed during construction, with a sealed vapor barrier under the concrete
- The vent pipe has no completely horizontal runs and minimal bends.
Even then, the passive systems cannot overcome high emanations of radon.
What is the best way to reduce levels of radon in my home?
Converting your passive radon system into an active radon mitigation system is the best way to reduce levels of radon in your home. So long as there is at east three feet of accessible, vertical vent pipe in the attic, we can convert your passive radon system into an active system. There are many other factors that determine the ease of an install, such as whether or not another contractor renders the vent pipe useless during the build process.
Even if you have a passive system in place, you should test your home A passive radon system does not guarantee you will have an acceptable level of radon in your home. The best way to find out if your radon levels have been sufficiently reduced is to have your home tested.
Do you have a passive radon system that needs work? Give us a call at 630-499-1492 today!