“What is radon?”
“Why is this just coming up now?”
“I never had an issue during my time living in the home!”
“Should I be concerned about my health now?”
“How fast can this get done? I have to close on the home soon!”
“How much does it cost to mitigate radon?”
We hear these questions and statements almost daily from homeowners in the process of selling their homes. A lot of you reading this probably have the same type of questions, and for good reason! Many times, the high radon test comes as a surprise to the current owners and causes a lot of stress for all parties involved, especially if there's a tight closing date in play. More and more buyers are demanding that radon testing be performed before purchasing a house. If the radon test fails, the buyer will make the sale contingent on the installation of a radon mitigation system similar to other home repairs like roof and plumbing work. So, to take a little bit of stress off of you as a home seller, here are five things you should know about radon!
1. Radon can’t be seen, smelled, or felt, but it is a harmful carcinogen.
Simply because radon cannot be detected by the human senses, that doesn’t mean it’s not a threat. Radon gas comes from the decay of uranium in the soil and when it rises up from the soil under your home, it can get trapped and sucked into your basement due to the pressure differential between the soil and the home. Radon gas becomes harmful as it decays because it gives off radioactive particles that damage the lining of the lungs, and over time this can cause lung cancer in both humans and animals. We get a lot of calls from upset home sellers who are obligated to fix the radon problem in their home before being able to close. Usually it’s one of two reasons why they are concerned. Either they think radon is a myth or a hoax because they haven’t been affected by it when they were living in the home, or they are concerned for their health going forward because they were unaware that they had been living in elevated radon levels for years. Radon typically takes years to take effect on the body if at all. Everyone’s body is different, so simply because you were not affected, that does not mean that the new homeowners will not be.
2. Radon has always been an issue
Radon gas has always been a threat even if you had never heard about it until now. Similar to how asbestos became something to watch out for, radon gas wasn't fully understood or taken seriously until semi-recently. Even as more information comes out about its dangers, public awareness about radon is still very low. More and more states are starting to regulate radon mitigation and radon testing and urging homeowners to take action. Radon mitigation isn’t a new fad, or trend that will fade out after a few years. Mitigation is a proven method to keep radon gas out of residential homes and commercial properties indefinitely, protecting the occupants inside.
3.You should be aware of radons effects, but don’t panic
We are writing this article mostly to inform you to the reasons why the buyers of your home feel it is important to install a radon mitigation system, not to scare you. If you feel like you have been exposed to high amounts of radon over a long period of time and are worried about your lung health, talk to your doctor. They will be able to give you more information and check if you have had any lasting effects. As mentioned before, radon can take a long time to take effect and everyone is different. You could be completely fine, but the next homeowner could be the ones affected. Knowing more about radon gas and how to prevent it in your next home will only help you when making the next purchase and with your future lung health. The EPA, the CDC and the American Lung Association all have great information on their websites regarding the effects of radon gas if you wish to explore more.
4. Radon mitigation can be a painless process, and the pricing depends on your home
Radon mitigation is a half day job for an experienced and certified mitigator, and typically we schedule installations about a week out, but can usually make accommodations for tight closings if needed. Estimates for radon mitigation systems can be given over the phone, through email or in person with a proposal sent to you via email in minutes. The price for radon mitigation largely depends on how your home is built. Typical prices for residential radon mitigation systems are between $800-$1500. For real estate transactions we can install the system for you and do the retesting digitally to get you the results in as little as 3 days after the installation to ensure that you have all the paperwork before you close. We have been in business for over 21 years, and in that time we have perfected the radon mitigation process to make it as painless as possible for our customers. We have a full time office staff and multiple installers, so you can be sure that we will answer the phone for radon related questions and estimates, and we won’t be booking out further than a week or two to do the installation.
5. Your next home should be tested as well
If you're moving to another residential home you should request a radon test at that property too. Now that you know the effects of radon gas, you might as well reap the health benefits of a radon system at home you will be living in for years to come. You will most likely have to install a radon mitigation system at the home you are selling, so why not find out what the levels are at your new home and work out a deal with that seller to mitigate that home as well? Don’t risk your health any longer! Radon testing and mitigation saves lives. If you live in Wisconsin or Minnesota, call us anytime for radon testing and mitigation questions as well as a free quote! If you live outside of our service area, feel free to call anyway, we can guide you through the process and let you know what to look out for when choosing the right contractor for the job.
Lifetime Radon Solutions
In the radon testing and radon mitigation industry, we deal a lot with customers who are in the midst of a real estate transaction. This is so because the home inspection is many times the first time the seller of the home has ever conducted a proper radon test. As deadly as elevated radon levels can be in residential homes, public awareness about its dangers is still very low. Both buyers and sellers tend to get overwhelmed about elevated radon test results during the inspection of the home, but we can help you make the process go as smoothly as possible. To help you decide what actions you need to take to keep you safe in your new home, here are the 5 things you need to know about radon before buying.
1.RADON IS A SERIOUS HEALTH HAZARD:
Radon gas is a Class A carcinogen, which means it is known to cause cancer in humans. Radon is actually the second leading cause of lung cancer in the US, only second to smoking. In non smokers, radon is the #1 cause of lung cancer. Humans are not the only ones affected by radon either, pets can develop lung cancer from radon gas as well, and are actually more susceptible to the effects because of their increased breathing rates. In either case, the effects of radon gas are not something to scoff at or ignore. Every homeowner should be aware of the effects of radon and how to monitor and control it in their home. Where does radon come from you might ask? Radon comes from the natural decay of uranium in the soil underneath your home. As the gas rises to dissipate in the air, the presence of your home blocks it from venting so it becomes trapped. Due to the pressure differential between your home and the soil underneath, radon can get drawn in through cracks in the floor, the sump crock, or even simply the pores of the concrete. Once inside, radon tends to build up in the lower levels of the home due to its density, and because of how long it takes to decay, radon can build up to unsafe levels throughout the living space.
2. RADON IS A FIXABLE ISSUE IN ANY HOME
If the home you're buying does test high for radon gas, as scary as that may be, it should not deter you from buying the home. Elevated radon gas levels can be fixed in any home by installing a proper radon mitigation system. At levels of 4.0pCi/L or above, a radon mitigation system is recommended in the home, but don’t fret if the current levels are substantially higher than that. We have found that even homes with levels as high as 80-100pCi/L can be brought below 4.0pCi/L with a custom designed radon mitigation system. Our most typical retest results for residential homes fall below 2.0 and many coming even below 1.0. There may be many different factors that you consider when deciding whether or not to buy a certain home, but due to proven removal techniques, radon gas shouldn’t be one of them.
3. THERE ARE MULTIPLE OPTIONS FOR MITIGATION:
We find that a lot of home buyers worry about the aesthetics of a radon mitigation system because they have seen other radon systems online or in their neighborhood that they didn’t like. While we agree that white PVC piping and a fan might not be the most ideal object to be placed on the exterior of your home, that doesn't mean it can’t be hidden. Homes with an attached garage can usually be fitted with a garage style radon mitigation system. Garage style radon mitigation systems have the piping and fan run from the basement, into the garage and then through the roof. A garage radon mitigation system, if possible, is the most aesthetically pleasing option for radon mitigation. Obviously, every home cannot be fitted with this style of system, but even if an exterior option is the only way to go, there are usually multiple options as to where the system can go on the exterior. We always work with our clients to find the spot on their home they are most comfortable with, so if the home you are buying needs a radon mitigation system and has to be installed before you move in, it is a good idea to be there on the day of install if possible.
4. WATCH OUT FOR RADON TESTING FRAUD
Unfortunately in the radon industry, we see a lot of radon testing fraud. Some homeowners want to avoid the possibility of ever having to install a radon system themselves even if it means lying to the buyers, endangering their health. You can even see the prevalence of this by looking at how many people search Google for questions such as “how to pass a radon test” or “how to fool a radon detector”. Radon testers are not completely tamper proof and cannot be watched for the full testing period by a professional, so during the testing process, we’ve seen sellers open windows, or even move the test to the top level to make sure it comes back low no matter what. There isn’t a lot that can be done about this, however it is an important thing to be aware of. If you have a test done by an inspector and then the seller conducts their own test with a much different outcome, it may be time to question the results. Additionally, the EPA recommends testing every two years, so if the results are low when you buy, you should still have another test conducted soon after moving in.
5. GOING CHEAP CAN END UP BEING EXPENSIVE:
Not being a part of the installation of a radon mitigation system for the home you are buying can end up being costly for you. If left up to the sellers of the home, they may choose the cheapest option just so they can get it done and get the closing over with as soon as possible with the smallest cost to them. Quality radon mitigation systems installed by certified and experienced contractors should cost anywhere between $800 and $1500. If you see a quote below that, you may be getting a low quality system in the end. Radon mitigation systems that are installed improperly or installed without proper permits being pulled for electrical (if needed), can cost you a lot down the road. The costs that can ensue after a poor installation include but are not limited to; fines from the city, service call costs to fix unsatisfactory work, time wasted by trying to contact the company for service, or even the cost of having the system removed and an entirely new system installed to get it to code or working as it should. Try to be a part of the mitigation process with the sellers of your home, and check reviews as well as company history before making a decision. We have fixed far too many improperly installed systems over our 21 years in business. If you are going to have mitigation done at your new home, make sure it’s done right the first time.
Lifetime Radon Solutions
The process of radon mitigation within residential structures is generally a simple concept. For the vast majority of homes in Wisconsin and the rest of the midwest, some form of sub-slab depressurization is the most effective way to reduce radon levels within the home. That is, either depressurizing the drain-tile system or depressurizing the soil/material beneath the slab when no drain-tile is present. The reason this concept works so well is that the negative pressure differential between the home and the soil beneath the home is the main cause of the “vacuum” that draws the radon into the structure in the first place. Many times this pressure differential is caused by natural occurrences (like barometric pressure changes, wind, etc.) and other times human actions (like heating the home, running exhaust fans, etc.). In more simplistic terms, since radon is a gas derived from uranium particles in the soil, when the home “breathes” it releases air out and ultimately has to replace that air with new air from outside the structure.
During this process, the home can draw in new air from beneath the slab (many times with high radon concentrations), into the structure where it is encapsulated and can grow to more dangerous concentrations over time—much greater than the highly diluted outdoor air. By “overriding” the natural pressure changes and human originated pressure changes (through the use of a proper radon fan), the radon system will ultimately draw the radon into the exhaust piping rather than into the structure. This concept of sub-slab depressurization is also effective because it stops the radon before it enters the home in the first place. Again, in layman’s terms, by using a PVC venting system powered by a specifically chosen radon fan (ultimately creating a vacuum under the slab), we can override the natural pressure differential that is present and ultimately draw the radon into our piping, rather than into the structure, and property reroute it to vent above the roofline (so there is little to no chance of reentry into the home). Some homes have different foundation styles or may contain crawlspaces, and in that case, a similar depressurization process is used—only the process involves sealing the crawlspace with vapor barrier and drawing the air from beneath the vapor skin rather than beneath a concrete slab. Although the process or concept is rather simplistic, the implementation and installation can become complicated. The following information is how I explain to customers the biggest misconception surrounding radon system installation nearly every time I do a radon installation quote...
Most every time I enter a home to do a radon mitigation system installation quote, I ask the customer to start things out by showing me where the sump pump is, or ask if there is a sump pump/sump crock at all. I do this for a few different reasons but mainly because I can generally identify if there is drain-tile present, how the drain-tile is run, what kind of drain-tile is present, and whether or not there is a submersible sump pump or a pedestal-style sump pump present. Nearly every time we get to this part of the process, the conversation comes up about system placement and the biggest misconception about radon mitigation in residential properties is brought to the surface. That is, most every homeowner I speak to thinks that the radon system MUST come out of the sump crock. This belief is false. We do not have to run the radon system out of the sump crock. That is simply one way to install the radon system and in most situations it is not the preferred method of installation for these 3 reasons:
1. Generally the sump crock is in the front corner of the home and because of that, system placement and aesthetics for exterior placement is not preferred.
2. Many times the sump crock is a busy area—meaning you have multiple pumps and pipes exiting in this area and there may be hoses from dehumidifiers or other appliances running into the crock in this area, etc. Therefore, adding another pipe into the closed or sealed radon cover may overcomplicate things if the customer needs to change their sump pump in a hurry.
3. Sometimes, depending on sump placement, there may be code issues that preclude the contractor from placing the system in this area (this could be its own post entirely, so for the sake of keeping on topic we will keep this point general).
There are really only 3 reasons that I do recommend to install the radon system out of the sump crock. Those reasons are as follows:
1. We prefer to run directly out of the sump crock if the customer has a very active sump pump/drain-tile system. If the sump is continuously running, that generally means that the drain-tile is full of water. Since the drain-tile is used to pull air through the system, the existence of water will preclude the system from operating effectively (if we tie into the tile directly, and it is full of water, it is difficult/impossible to pull air/gas through water). By utilizing the sump as the collection point, the system will be more effective because the water pressure will force any soil gasses and air into the sump basket and the fan will of course remove those soil gasses and vent them properly above the roofline/gutter-line.
2. If the customer or current homeowner has had drain-tile work done and the basement company that completed the work voids the warranty if we connect into the drain-tile directly, then we would of course prefer to run out of the sump crock to ensure the customers warranty remains intact.
3. If the homeowner or customer is not sure where the drain-tile runs (depending on the age of the home, the builder, or a multitude of other reasons, the drain-tile may not go all the way around the structure or may not run next to the footing-sometimes referred to as a “spider system” because the system may have several “legs” and/or resemble a spider from an arial point of view). In this case, it may make sense to use the sump pit as the collection point. Further, it doesn’t make sense to drill holes into the customers slab to try and find the tile (this is of course both damaging and time consuming) and usually it is much easier to just simply depressurize the sump, test pressure field extension (the area beneath the slab where the fan is able to pull air through the sub- slab material and ultimately show a negative pressure differential on a micro- manometer) or retest the radon levels, and if the PFE is not proper or if the levels are not properly reduced, then the technician can add another drop point to increase the pressure field extension. Many times, this happens when the home was built before modern building codes were present or if the individual that built the home did things “their own way."
It is important to understand that piping directly out of the sump crock is a necessary and effective means to achieve proper radon mitigation but certainly not the only means. However, the above information explains why it may make sense to pursue this method and why it may make sense to seek out other routes for your radon abatement system. Most customers prefer their systems to be run to areas outside of the home that are hidden or out of plain site. Moreover, homeowners with ranch style homes or homeowners with attached garages (with no living space above) may prefer for the system to be run through a closet or up through the garage and eventually vent out of the roof of the home. In these cases, depending on sump crock placement, it usually makes sense for the system to run directly out of the drain-tile to achieve this placement rather than out of the sump itself. That is, running horizontal pipe for 10, 15, or 20 feet out of the sump and across the basement to get to the chosen area outside, in the garage or up through a closet, etc. may deem the system ineffective because of reduced/inhibited airflow or other detrimental flow metrics. Additionally, it would be more laborious, more expensive and most likely more intrusive/obtrusive to run 3 or 4 inch PVC across the basement. Therefore, utilizing the sub-slab piping that is already present and
ultimately hidden from the living space is much more practical and effective because it allows for a more direct venting route while still achieving the aesthetics desired by the homeowner.
In conclusion, venting a radon system out of the sump pit or directly out of the drain-tile are both effective means of radon mitigation. The only reason the sump pit is used in radon mitigation is because of the drain-tile piping that wraps all the way around the entire footprint of the structure. It allows us to create a great pressure field extension under the home. This is precisely how a 3-inch radon pipe on one side of the home can mitigate the entire structure. Because the unseen piping underneath the slab is both open to the soil and present all the way around the entire footprint of the structure, we are able to pull air from underneath the entire structure by tying into this system. Therefore, whether we tie into the sump pit itself or into the drain-tile system directly, we achieve the same or similar result—a depressurized drain-tile system that allows us to effectively pull radon gas from beneath the structure and vent it safety into the outdoor air. Which method is best? That is determined on a case-by-case basis and is generally based on the customers preference and on the many factors listed above!
Brian S Thompson
Lifetime Radon Solutions
We get asked a lot if simply opening windows in the home can lower the radon levels to a safe and livable level. The answer to this question is a bit complicated, because yes, in some cases the home’s levels can be lowered temporarily by opening windows, but not only is this not a sustainable solution, it has the possibility of causing other issues as well. Let’s go over a few reasons to why opening windows is not the right solution to keeping you and your family safe from radon gas in the home.
1.Opening windows is not a sustainable solution:
If your home has an elevated level of radon gas, this means that radon gas is coming up from under your home from the soil and getting trapped under the slab. Once trapped, it seeps into the home in a multitude of ways due to the pressure differential between the house and the soil. Opening the windows does help bring fresh air in and circulate the radon gas out, however, once you inevitably have to close your windows during the night, or in the winter time, the constantly rising radon gas levels will build right back up into your home within a few hours. Additionally, it is not advised to constantly leave windows open to simply take care of one issue such as radon gas, because essentially you will be losing far more money in heating and cooling costs than you would by simply installing a proper radon mitigation system.
2. You will still be exposed to radon gas before it can escape through the windows.
As mentioned before, if your home tests high for radon gas, that means there is a decent amount of radon gas rising from the soil under your home. Opening windows can help ventilate radon out, however in that scenario, you are already letting the harmful gas inside before letting it slowly vent out. Radon mitigation systems pull the radon gas out before it even has a chance to enter the living space, so you won’t be breathing in elevated levels at all before it gets safely piped out.
3. Sometimes leaving the windows open can increase the radon level in the home.
In some cases, albeit more rare, leaving windows open in the home can create a negative pressure differential between the soil and the home that can actually draw more radon gas into the living space. Weather conditions, and which windows are actually left open all play big factors to whether the radon gas is being drawn out, or sucked in. The only reliable method of keeping your radon levels low whether the windows are open or not is radon mitigation.
In conclusion, leaving windows open can only act as a temporary solution to elevated radon levels before you can get a more permanent solution installed such as a proper radon mitigation system. If you have questions regarding radon, radon mitigation, or radon testing, give us a call any time! We are here to help.
Lifetime Radon Solutions
1. Your health:
By far the biggest reason you should have a radon mitigation system installed in your home is to keep you, and your family safe. Radon is a class A carcinogen, which means there is evidence that it causes cancer in humans. The Environmental Protection Agency (EPA) estimated that over 21,000 people in the US alone die from radon induced lung cancer annually. So, as the second leading cause of lung cancer only to smoking, radon poses a large threat to homeowners, and the scary thing is, it's invisible. Unlike smoking, where most everyone knows the risks and you can see and feel the smoke going into your lungs, radon cannot be smelled, seen, or tasted. The decay chain of radon is what poses the danger to human lungs, and the radioactivity that is emitted is what causes cancer. With the emergence of new technology, radon gas can now be easily detected with the use of test kits, and digital testing monitors. This means more and more homeowners are able to test their homes easily and for an affordable price. Don’t risk you and your families health by ignoring this cancer causing gas. Have your home tested, and mitigated if the results come back above 4.0pCi/L.
2. Increased value of the home:
Much of our business comes from homeowners in the midst of selling who ultimately need to install a radon mitigation system as a condition of the sale. What this means is, most new home buyers are demanding homes that have low radon levels before they move in. We’ve even seen instances where high radon levels almost ruined the sale because the buyer was afraid that the home was a health hazard. Fortunately, radon can be effectively removed from any property for less money than you may think. Once installed, radon mitigation systems run continuously keeping radon from entering the home, so when it comes time for inspection, you won’t have to worry about failing the radon test. Comparatively to other home repairs such as roofing, HVAC, plumbing, and electrical, radon mitigation is much less of an expense. Additionally, radon mitigation can be completed in less than a day with retest results back in less than a week.
3. Moisture reduction:
An unintended but certainly welcome byproduct of installing a radon mitigation system is moisture reduction. Most homeowners see a significant difference with the humidity levels in their basement after a radon mitigation system is put in place. A lot of homeowners tell us that they no longer have to run their dehumidifiers at all, while others say they run dehumidifiers significantly less than they normally did before. There have been studies done by the EPA on moisture reduction from radon mitigation systems that showed statistically significant reductions in moisture levels in the basement over time, so not only will you be drawing out dangerous radon gas from your home, you will also be keeping your basement dry, which is pretty cool!
4. Piece of mind:
Radon mitigation systems are designed to not only reduce the current radon levels in the home significantly, but also to keep them low indefinitely. Radon levels fluctuate throughout the year, and can change drastically as time goes on or as new cracks form in the basement when the home settles. If your radon levels were at 3.0 pCi/L when you bought the house, there’s a good chance that the levels could surge up above 4.0 pCi/L in just a few years. Some homeowners like to live on the edge and risk not taking action on their radon levels, but most people are concerned with their health and can achieve the piece of mind that they are safe from this cancer causing threat by installing a radon mitigation system. With a radon system, you can rest easy that there is a continuously running device in place to keep radon out, and keep it out for years to come. There’s no more worrying about pressure changes and different times of the year making your home unsafe, a radon mitigation system is designed to keep your radon levels low year round.
5. Elimination of mold and mildew smell from open crawl spaces
Many homes throughout Wisconsin and Minnesota have open crawl spaces in the basement or under additions, and this can be a major source of radon and mold. In addition to installing a radon mitigation system in these homes, we also seal down the crawlspace with an airtight vapor barrier. This not only helps with keeping radon from rushing in through that open space, but also helps with the musty smell that many times emanates from such crawlspaces. The vapor barrier also helps with moisture in the basement, and can protect from all other soil gases coming up into the home as well. Once sealed down, you will undoubtedly notice a drastic improvement in air quality of the basement, and aesthetically, it looks a lot cleaner.
For more information on radon mitigation, and it’s benefits, you can always reach us by phone or email. We offer free estimates to all homeowners living in Wisconsin and Minnesota!
For those who already have a radon mitigation system installed in their home, the question we get a lot is, “what do I need to do to maintain my current radon system?”or “can you make sure the system is still working as it should?” and “what do I do if my current system doesn’t adhere to current code or EPA standards?”
Listed below are the answers to a few of these frequently asked questions:
“What do I need to do to maintain my current radon system?”
Once a radon system is installed, homeowners really only need to do two simple things to ensure their system is running effectively.
“Can you make sure our radon system is still working as it should?”
Absolutely! Whether your system is installed by us or any other company, we are always available to come out to your home to assess your radon mitigation system and fix whatever may be wrong. Fan issues are what we run into the most, and many homeowners fear that once the fan stops working they have to install a whole new system. This is not true at all. For a much lower cost than installing a brand new system, the fan can be replaced by us. If your current fan is buzzing, clicking, yellowing, grinding, or not running at all, it may be time for a replacement. The line of fans that we use are known to be one of the top radon mitigation fan manufacturers in the industry. You can check out Festa Radon Technologies by clicking HERE and read about what makes them different in the marketplace. Our fans do not yellow from the sun and typically last longer than 7 years. If you have a fan that is specifically tailored to fit in a certain area, we can special order the same brand you have, or modify the piping to fit a new fan. We also offer a variety of upgraded fans if you are not comfortable with the current levels your system is producing.
“What if my existing system doesn’t comply with the current EPA standards?”
We run into a lot of systems that were either installed a long time ago, or done by someone not certified in radon mitigation. If this is the case, the system must be modified or replaced in order to pass inspection when selling the home. The most obvious signs that your radon system isn’t up to code are as follows:
If your current system has one or more of these issues, it will most likely be flagged when it comes time for a home inspection. However, many of these things can be fixed without having to install a new system. We can reroute and extend existing piping, move the fan to an acceptable place, seal the sump crock, replace the sump pump, and add a manometer if needed. If you feel your system isn’t up to code, or it doesn’t pass an inspection, give us a call and we can help!
Homeowners frequently ask us if we put a cover on the top of the radon mitigation piping, and it’s a good question. It does seem like it would be a good idea when you look and see a pipe open to the elements. However, as we will explain in this post, not only is it not necessary for the system to be effective and to protect the fan, pipe covers can actually reduce the effectiveness of the system itself and cause big issues in the winter time.
Lets first go over the main questions we hear from homeowners when they see the opening in the top of the pipe.
Won't rain get into the piping and negatively affect the system?
The radon mitigation fans that we use are designed to handle water coming through the piping, and if water does come down into the pipe when it rains, the water will simply drain back into your drain tile underneath your home to be pumped out again from your sump pump. In our 21 years of business we have never encountered a water issue from rain trickling into our systems piping.
Won’t leaves and other debris get into the piping and wreck the fan or clog the pipe?
The airflow moving through our piping is quite substantial, and it is very rare for debris to find its way into the pipe without getting blown right back out, or getting deterred before it can even get close to going in.
What about animals?
Due to the amount of air flow constantly running through the pipe and how quickly it is exhausting, most, if not all animals stay away from opening to the pipe. In extremely rare cases if an animal does get in, that would be covered under warranty.
Why a cover can be detrimental to your radon system:
Pipe covers can cause your system to freeze over in the winter: When your radon mitigation system is running, it is pulling air from beneath your homes foundation and safely venting it above your roofline. In the wintertime, the outside air is much cooler than the air from underneath your home and this causes condensation to form. With a cover, the condensation starts to build up and freeze over, eventually causing it to freeze over the top of the pipe completely. Once this happens, the radon fan can no longer pull and push any air through and the system becomes useless. This is especially bad because radon levels tend to be higher in the winter time due to closed house conditions, stack effect, and other temperature/pressure differentials. Therefore, with a frozen over system you will start to accumulate high levels of radon in the basement with nothing to extract it out.
Less Airflow: Nearly all covers will affect the amount of airflow running through your radon mitigation piping. To run at peak efficiency and keep your levels as low as possible, the top of the pipe should be left open to allow the most airflow possible.
In conclusion, putting a protective cap on the top of your radon system might sound like a good idea in theory. However, due to the factors discussed above and the fact that it is not necessary, it is something to avoid when installing a radon system in your home.