Understanding Passive Radon Reduction Types.
Sealing openings like cracks, sump pits, dirt or gravel crawl spaces, around sewer and water lines or any other opening that may allow radon to enter the home is a basic part of most approaches to radon reduction. Sealing does two things, it limits the flow of radon into your home and it reduces the loss of conditioned air, thereby making other radon reduction techniques more effective and cost-efficient. EPA does not recommend the use of sealing alone to reduce radon because, by itself, sealing has not been shown to lower radon levels significantly or consistently. It is difficult to identify and permanently seal the places where radon is entering. Normal settling of your house opens new entry routes and reopens old ones.
Problem with passive, example;
Let’s say I get a call to do some passive radon reduction, I seal large cracks and the sump pit on a home that had a radon level of 5.1 pCi/l. Everyone involved in radon knows radon levels fluctuate, on an hourly basis the changes can be quite drastic, over time (days) the change becomes smaller because you’re taking an overall average. It is possible however that on a two day test one test can be 5.1pCi/l and a two day test the next week could be 3.8 pCi/l at the same home without anything being done to the home. The point is, did the sealing actually have an effect on the radon level or was it just random chance that the follow-up test was below 4.0 pCi/l?
The contractor said he gets good results with passive; Maybe, personally we find there is a 50/50 chance that the re-tests after passive will be below 4.0 pCi/l when the original radon level was at or less than 6.0 pCi/l, keep in mind that this is still a temporary fix.
Buyer Beware; Some contractors will try to convince you that sealing is the way to go (everyone wants to save money) and that they have had very good results with passive, even though they’re not offering any guarantees the passive will work. This may just be a way of getting their proverbial foot in the door, believing once they have started the work you will call them back to do additional work should the passive fail to lower your radon levels. In the long run, with re-testing and the additional time this can end up costing $200.00 – $400.00 over a normal active system installed right from the start.
Passive New Construction System (same as passive stack) is a pipe system installed in new construction that relies solely on the convective flow of air upward in the vent pipe for sub-slab depressurization and consists of a vertical vent pipe routed through conditioned space from the suction pit to 12 inches above the roof. All of this can be concealed inside of the walls just like your plumbing lines during construction.
Passive Stacks are installed during construction or after, for all intensive purposes it is an active radon reduction system without a fan. When installed in new construction as described above a passive stacks’ main purpose is to have a means of making an unobtrusive active system in the event elevated radon levels are found.
Passive stacks installed after construction in an attempt to lower radon levels on their own is, for lack of a better explanation, a waste of time and money. If you’re going to go through the effort and cost of installing the piping, for just a little more you can have a fan and a system that’s proven itself to work.
For more information on Passive Stacks go to New Construction.