• Randy Weestrand
    I’m troubled by changes to the mitigation standards that are currently in the review process, or were recently approved. Are these changes needed, or are we watching a case of “Rule Makers Gone Wild”?

    1. A proposed revision to the mitigation standards is currently under review until March 20 at https://standards.aarst.org/public-review/ . It requires the installer to do sub-slab communication testing with a micromanometer on every home once the system is complete and operating.

    Can anyone provide data to support the need for this testing in your standard 1,200 square foot “no-brainer’ with drain tile or clean rock under the slab?

    Can anyone provide data supporting the need for a micromanometer as opposed to smoke?

    2. The mitigation standard revised on 12/20 changes the horizontal pipe support requirement from 6’ to 4’. This exceeds the required support for plumbing pipes- which can be assumed to be full of water, as opposed to cool underground air.

    Can anyone provide data to support this change?

    3. The mitigation standard revised on 12/20 requires that a discharge within 10’ of a window must now be 4’ above the window, as opposed to 2’.

    Can anyone provide data to support this change?
  • Steven Reichert
    These changes are bordering on insane with little science behind them. The biggest problem stems from including soil gas standards with radon mitigation. They are not the same and need to be separated. Unlike most soil gas (VOCs etc.), radon can be easily and cheaply tested following a mitigation project. PFE testing is good practice and a predictor is a system "may" work. Radon tests are the proof that is does. Combining these standards is a mistake. I've had enough of the soil gas community highjacking AARST. Go play in your own VOC sandbox.
  • Jeff Tikkanen
    Before we take on any new standards, let's verify whether we have to run vent pipes up the sides of homes in the first place. The Canadians do not. Instead of shooting from the hip, let's do valid research to verify which standards are necessary and which standards are just the latest machination of a standards writer.
  • Colin
    Hi Jeff. In Canada we are obligated to perform extensive diagnostics on every job. Does it take a long time? No - with a fantech PFEDK it can take minutes to complete and produce a detailed report to support your design. The trick is that Canada has an official design process while the US does not. We measure the natural pressure (closed house) and multiply by a "stack effect" temperature adjustment factor to determine our target pressure which is different for every home. Takes 30 seconds. If we can demonstrate that amount of pressure change over the entire slab then the radon will be taken care of under the prevailing conditions and also in the cold months. The average post mitigation results from our last 1000 jobs is about 0.6pCi/L. It works. 97% of those are using a 15 watt fan as extensive sealing is also required. Is it worthwhile? Yes - since pressure change at the far test hole is a linear function of airflow, if the design says you need a change of 1Pa and you make a 3 Pa change, then you are moving 3X too much air and you are installing a more expensive fan than you need. Smoke doesn't tell you how much pressure you have so you don't really know if you have enough negative pressure or too much - maybe too much. Plus the cost,energy and noise penalty associated with the wrong fan. Mitigations in Canada are also more expensive - it takes one 8hr day for a job - not for the communications testing but for all of the sealing and optimizations to get super low levels and a quiet system. So a typical range across the country might be $2000 - $3500 and quite a few mitigators are engineers. The thing is that we don't have and nor do we want, a radon industry built around real estate testing where you have to be cheap and fast to survive. So while our design and sealing and documentation yields efficient, quiet systems and well-paid professionals, it may not translate down South unless you can get customers who recognize the extra value.

    Even in a real-estate market where radon systems are really real-estate contingency-removal systems, the bottom line is that for the 5min it would take to use the PFEDK and our design process, you can show some extra value to the customer, eliminate call-backs, save money on the fan sometimes, make quieter systems and maybe make a bit more $$$ for 5 min worth of easy work. But everyone has to figure out how best to run their business and your market is different across the country so I'm not preaching - just offering another perspective that might help mitigators add value which means they can make more money in the right situation.

    It's true though - I can't figure out why they would make you measure pressures if you don't have a process which tells you how much pressure you need. What's the point in that? Is -1Pa good, is -10Pa too much? Maybe its just baby steps but what you really need is a process that tells you what pressure you need to see for that particular house and then you can use the manometer to prove you can demonstrate that pressure. Did I mention Canada developed that process 15 years ago? Just steal our process until you can figure out your own. Download the Professional Contractors Guide and look up chapter 4 or contact me and I can send you a easier spreadsheet version. Or get a PFEDK and just use our process to determine the design pressure and the PFEDK to determine the system curve and print the report. It's super easy and adds value and removes risk.
  • Steven Reichert
    Collin - I'm kind of amazed that you can use a 15 watt fan on the majority of your installations. Our typically garage attic fans require such long pipe runs, 30 to 40 ft (10 to 12 meters) plus multiple elbows to get to the required discharge point that the pipe resistance would consume most the available suction from such a small fan. Do you typically use an interior fan with a sidewall discharge?
  • Steven Reichert
    FYI Randy, the plumbing code did change a couple of years ago to require 4 foot supports on horizontal piping to appease the powerful J-Hook lobby. The standards should just say "meets or exceeds" local plumbing codes instead of alway having to adjust to code changes.
  • Colin
    Hi Steven
    The PFEDK breaks out the static pressure drop for both the soil as well as the piping at your design airflow and plots that on a graph so you can see which fan will overcome those pressures. The pressure drop in pipe is a squared function of velocity so the resistance really goes down to nothing at low flows and goes way up for high flows so it depends on the air flow needed. But if the design says you only need a small pressure change and that can be done with a small fan then that’s perfect. I don’t have much visibility for this but I wouldn’t be surprised if there is a tendency to overshoot the target pressure to the extent that a larger than necessary fan is being used. A US fan manufacturer once told me that he can’t figure out why they sell so many small fans in Canada and almost none in the US. Part of that might be because we have a design process. Plus, I recognize, we have all day to build a system so we can seal leaks or gopher in tight soils if needed. Our customers would not pay us for 3.9 - they want ALARA - As Low As Reasonably Achievable.
    BTW you can access the PFEDK app online without buying anything and play around with it to see the impact of changing pipe length or pipe diameter on your design. PFEDK.app . Thing is, it may not make a ton of sense without having the device but I can give you some values to enter that would be similar to what you might see on a real job to get started. I also find if you email the report to yourself it makes a nice one page report that you can give to the customer in your report.
    Also, I’m talking about the PFEDK because it’s easy and it works. Instead, you can download the chapter 4 I mentioned last post and do all the same calcs manually which is perfectly fine also.
  • Jesse Green
    Thanks for the post, Colin! I'd love to chat with you about how you calculate the design pressure. That's something I've always wondered. I'd also be interested in your spreadsheet.

    Thank you!
    612-474-1004 ext. 3

    Here's a link to the Professional Contractors Guide https://carst.ca/resources/Documents/Reducing%20Radon%20Levels%20in%20Existing%20Homes%20A%20Canadian%20Guide%20for%20Professional%20Contractors-E.pdf
  • Henri Boyea
    Our processes have evolved over the years to where we use a 20-watt fan on 90% of the homes we mitigate that have crushed stone under them. Those with dirt or red clay often require a high-suction fan.
  • Henri Boyea
    I too, have concerns about the way Standards are evolving. Until every structure is built exactly the same way on the same soil it is ridiculous to attempt to use Standards to micromanage every decision on every job. I have quite a high IQ, a Bachelor of Science degree, and 25 years of mitigation experience, and it is my opinion that the Standards are becoming so complex that a normal person can not possibly learn (and apply in the field) all the details and nuances. The Standards should not become the Idiots Guide to Mitigation, but should assume some degree of competence and professionalism on the part of those who agree to abide by them. They should be guidelines, not shackles.
  • Jeff Tikkanen
    Hi Colin,
    You describe an interesting contrast in radon industry cultures that may reflect a contrast in Canadian and US cultures. Canada has a much stronger national identity, so it is easier to mandate a national design process for choosing a properly sized fan for a radon job. The United 50 States of America have fifty different approaches to addressing the issue of radon. There are varying levels of standards enforcement among the states, and levels of enforcement can change with the political winds.

    In the States, radon companies tend to be smaller mom and pa businesses. We are not engineering firms. As you mentioned, we tend to compete on price and volume, so we tend to wince at new mandates that may not be enforced. Sometimes we feel that many of the new mandates are not backed up with science or cost/value assessment.

    It may be that because our systems are relatively inexpensive, more are installed per capita in the US than in Canada (I'm guessing.) I cannot imagine many of my fellow Americans spending $2-3K on a basic radon system. I cannot imagine how expensive a radon system would be that incorporated a crawl space and adjacent upper slab to the system. Ironically, American radon systems may be less energy efficient but more effective overall because of the volume of systems installed. The primary goal of a radon system is to save lives.

    Most American radon contractors know how to perform pre- and post-mitigation diagnostics. We use them when we approach a more challenging home. We tend not to use them on a 20-year-old square box foundation in a neighborhood where we have previously installed radon systems. We do tend to wince about having to do extra paperwork that so many of the recent mandates require. Engineers and engineering firms tend to love to do paperwork. It justifies their actions, costs and credentials. Small businesses tend not to have the time or resources.

    I think the members of AARST need to think twice about each and every new standard that we try mandate. The more we regulate our industry, the more expensive it becomes for the small business and the more advantageous it becomes for the larger radon/soil gas mitigation firms who already have the regulatory resources built into their business infrastructure. If we are not careful, we will have a radon industry that is closer to the Canadian model: an industry with less contractors and more profit for per job at the expense of consumers.

    Colin, I appreciate your comments, though I use them to make a different point. I still have to ask if anyone has done any research as to whether the Canadian practice of venting radon systems at ground level is any better or worse than the US practice of venting above roof eaves?
  • Jeff Tikkanen
    Thanks Jesse and Colon for the information on the Canadian Professional Guide.
  • Randy Weestrand
    Mechanical codes may have changed regarding hanger spacing for plumbing pipes designed to carry heavy slugs of water (think: multiple simultaneous toilet flushes). But Charlotte Pipe recommends 4' spacing only when ambient temperatures are above 120 degrees. https://www.charlottepipe.com/Documents/PL_Tech_Man/Horizontal_and_Vertical_Support.pdf
  • Colin
    Thanks Jeff - those are really thoughtful comments. I do want to clear up a few things so I don't misrepresent the "Canadian approach".
    1- I did mention that there are engineer mitigators. But the vast majority of mitigators are ma and pa shops similar to the US. Why I mentioned it was that it shows that its a serious profession that attracts engineers and building scientists - which I think is awesome.
    2-Since stack effect is a function of temperature - it's clear that you can develop a process where you measure the natural pressure under the slab and multiply by a correction factor to get a good estimate of the pressure under design conditions (not worst case but typical cold conditions) This is the most awesome part of our process because there is no guessing at the pressure you need to develop to fix that house. Like I mentioned, pressure change at the far holes is linear because it is laminar flow at the edges of the slab since the velocity is slow. So why move 3X the air to achieve a pressure target that the house already tells you is way too much. It's not more effective to be bigger than you need.
    3-Extra paperwork - yes who likes paperwork. I mentor the majority of Canadian mitigators and this is a common complaint. But why not work smarter not harder? I use an app on my ipad that costs $20. I build forms that show all the relevant information a customer would want to see like: natural pressure - design pressure - pressure achieved fan on fan off - photos of all work like sealing etc. - piping photos - discharge photos - fan curve and system design (from pfedk screenshot)- hazard assessment - rough sketch of floorplan with test holes and suction hole - manometer photo - fan serial number etc etc. It can take as fast as 5 min to complete the form and pdf to client. Adding a huge value to the customer and taking a very small amount of time. Plus this is required in our standards. Could you take 2 hrs to complete on PC in the evening? Sure - but why not take 5 min onsite instead?
    4 - question. You mention that most radon guys know how to do diagnostics. I was under the impression that you have no official design process. How do you know what your target pressure is for any particular house - I'm curious? A fixed pressure based on the height of type of house won't work.
    5-I do take your point about the comparison of getting a ton of houses to at least 3.9 compared to getting fewer houses to 0.6. Its a good point that I don't know the answer to although awareness has grown by leaps and bounds here so maybe we can get the volumes up even without real estate transactions. Most mitigators I know are so busy and booking so far ahead we are already maxed out. I'm booking into May and June.
    5- Ground level discharge - I don't know what to say. It seems to work. Bill Broadhead has an interesting story about this. Apparently the US would also have had ground level discharge if it wasn't for a one week delay in the results of a wind tunnel test that showed that ground level discharge without a 90 on the end eliminated re-entrainment.
    6- Again happy to share the Canadian experience but as you point out your market involves so many different jurisdictions that what works here may not work everywhere without a shift in thinking.

    I hope to come down to the States to see how things are done there first hand. And feel free to tag along with me if you come up here (Calgary Alberta). We can cross pollinate ideas for the betterment of both.
  • Bill Brodhead
    Thanks for all the comments Colin. It is obvious that the world needs to be more science based and at the same time open to new ideas. I have a tendency to test ideas and concepts myself to confirm or disprove their value or truth. Straight line discharge can send measurable but certainly dramatically reduced radon 20 feet from a adischarge as per my study in 2020. What was apparent in the study was very little radon accumulated around the discharge location which explains why Canadian side wall discharge works or at least appears to cause little or no re-entrainment.
    Here is the link to the test which AARST will hopefully publish after some final reviews.


    Your diagnostics and careful sealing allowing 20 watt fans to work so well is a great example of measuring pfe post mitigation. The 1st step in my mind to getting to this place is to require mitigators to make post system PFE measurements. This is a tremendous way to make obvious you have over sized the fan or you need to do more thorough sealing or add more suction pits. You may have fixed a dozen homes in a development using the same fan but without checking the PFE it's more than likely they are either oversized if you also followed the guidance to seal the slab perimeter.

    When my crews would come back from a job or jobs I always wanted to see what was the sub slab pressure, where did they take it and what was the u tube reading.
    They would also regularly make PFE measurements before sealing using a test fan. They quickly learned that sealing even tiny perimeter cracks caused the far test hole to be 10 times stronger and sealing was a critical component not something to skip and use a larger fan to compensate.

  • Steven Reichert
    MN Plumbing Code 305.4 specifies a 4 ft. interval as do most local pluming codes that follow the national standard.
  • Marcel Brascoupe
    One other aspect here that Colin forgot to mention above is that mitigators in Canada look at radon mitigation from 2 angles.... one obviously is the reduction of the radon levels in the home and the second one is the health, safety and general economics for the occupants. We know that installing a larger than needed fan will obviously reduce the radon levels in the home to a very low level but if we assume that 50% of the air that is drawn by the radon fan is coming from inside the home, this could create possible back drafting problems with combustion appliances inside the home. In Canada, especially in the rural areas, we still see a lot of homes with fireplaces and wood stoves installed in the basements because of the weather we get up here in Canada and the high costs related to heating the homes for a good part of the year. This fact has increasingly become an issue over the last 10 years with the increased sealing and tightening up of the homes to minimize heat loss. When we have a very tight home, even the loss of a small amount of conditioned air from the basement causes undesired consequences for the homeowners in terms of back drafting of their combustion appliances and possible carbon monoxide poisoning. Our goal when installing radon mitigation systems in Canada is yes, to reduce the radon levels of ALARA and at the same time, minimize the loss of conditioned air and risk of back drafting issues which could cost us a lot of liability in the end. We need to find a balance between the two. This is where the we need to use precise instruments and a structured process to ensure we achieve both of those goals. Using a smoke pencil only tells us that we have achieved a negative pressure under the slab and that we will be able to prevent the radon from infiltrating into the home. It does not tell us that we might be pulling more conditioned air from the basement than what we really need thus causing additional costs for the homeowners on a yearly basis and possible back drafting issues. This can easily add up to hundreds of dollars per year. The homeowner will probably end up paying the cost of the system in additional heating and cooling costs over a 4 - 5 year period. Using a micromanometer to get precise numbers that we can rely on and having a well designed process helps to achieve that balance. Mitigator is happy and homeowner is happy. This process takes no more than 30 minutes during each job using the proper tools for the trade. And yes, like Colin, I install more 20 watt fans per year than any other type of radon fan. Every home is unique and we cannot rely on the data we achieved at a neighboring home to design our system for a different home in the same neighborhood. Its like saying that if we have the same two models of service vehicles and that each one will consume exactly the same amount of gas or fuel. One vehicle may be doing more work in a rural area while the other vehicle is doing more work in a city environment with more stop and go driving. The driver also has lot to do with the fuel consumption of the vehicles. Homeowners heat and operate their homes in different ways. This has an impact on the way we need to design our systems for each individual home taking into account those facts. Like Colin said, you can use Fantech's PFETK or communication testing equipment with a vacuum cleaner and pitot tube like that indicated in Health Canada's Professional Contractor's guide to accomplish your task. The trick here is using a micromanometer to get your precise numbers to work with. I can compare this to trying to cook a turkey in the oven. If we do not have a temperature dial on the oven that tells us what the temperature is set at in the oven, the only thing we know is that heating elements will be turning on in and that the oven will be heating up but we don't know if the temperature in the oven will be at 250 degrees F or at 450 degrees F. All we know is that the heating elements will be turning on and that the turkey will cook but we don't really know if in the end it will be undercooked or if it will be dry and burnt. That is essentially what the micromanometer is giving us as information. Precise numbers to work with. Is the cost of a good micromanometer in Canada worth it for mitigation work? You bet ya !!! I have at least one for every crew...More importantly, when homeowners see all the tools and the processes we use to design and get the job done, they realize that it is not something they could easily do themselves and this is probably one of the reasons that in Canada we are able to charge a going rate between $2500 to $3000 for for a simply radon mitigation job... And in most cases, they are happy and quick to pay that rate. Not something we see with a lot of other trades.
  • Jeff Tikkanen

    I enjoyed reading the Canadian Professional Contractors Guide. You asked what we actually measure in our diagnostics since we do not have an official design guide. First off we tend not to take stack affect into our calculations. I guess in colder regions that would be more of a concern. I am on the Ohio/Kentucky border. Many of my past clients have radon monitors at home, and they do not report dramatic seasonal variations in radon levels in their homes. I have retested one home every two years over the course of 12 years and the radon levels have always been within .02 pCi/L of the original post mitigation level of 0.8.

    Our design processes tend to be based on what instructors like Bill Brodhead teach us: With any older home or any home I any questions about, I always careful to use the appropriate fan for the substrate I am mitigating; I try (maybe not hard enough) to use just enough fan to move or manometer a couple notches left of zero under the slab so that I do not waste energy with an over-sized fan: I seal where we can; I attempt to verify the PFE once the system is up and running.

    None of my systems have ever failed because I did not write down the sub-slab pressure at the end of the job. They failed because I did not treat a radon source in the home. Once I discovered that source and treated it, we were good to go.

    Most of the homes that I have mitigated come in at 1.7pCi/L or lower, quite often below 1 pCi/L. In the last 20 years I don't recall ever settling for a post mitigation level of 3.0 or above. I am also a home inspector. I have tested a good number of homes with radon systems in my area, and I am always surprised how well they do even if they are not installed according to the strictest of state guidelines.

    Back to my original question. It appears that there is no good reason for not venting directly at ground level. If this is the case, why do we continue to run vent pipe above roof eaves? Is there a joy in climbing ladders that I have not discovered? That question, to me, is worthy of our time and fundamental to what we are doing, if we want to be science based and open to new ideas.
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  • Bruce Decker BGIS
    I can't speak to the additional piping support changes and I would agree that if it is not full of liquid then you don't need a lot of support.

    As for discharge locations I support a ground level discharge and how we do it up here in Canada. There is sound research, Bill's included, that demonstrates little to no re-entrainment. Of course use sound judgement and treat each site specifically (e.g. carefully consider a ground level discharge if the only available location is beside the kids sandbox). One of the benefits of ground level discharge is a short pipe run on the exterior which dramatically reduces the chance of freeze up in cold climate. If our goal is to reduce indoor radon the last thing we want is a plugged system at the time of year when indoor Rn is at it's highest.

    When you look at the Canadian design process and the correction factors for stack effect it is a very useful tool. If I did an install in the peak heat of the summer when stack effect is lowest and didn't adjust my design to compensate for drastic increase in stack in January I would be concerned about the not having sufficient delta P. I may get lucky with washout but to rely on that is poor engineering. I can see less need for this in the warmer states.

    I would be interested in looking at the the difference in stack over a day in a desert climate where days can be very hot and nights can be brutally cold. In theory you would design and install your system during the day in the peak heat/lowest stack effect time.

    As for recoding site information (i.e. post mitigation delta pressures) I can't stress enough how important good documentation is. I look at it from a contractual and liability standpoint. Good documentation is proof positive that you did what you were retained to do and that you met a standard or best industry practice. Pressure readings are quantitative where smoke is qualitative. If the owner isn't happy and has another party come in to investigate your work you have something showing you did it correctly and you were "duly diligent". In my mould consulting days I testified at a case. The contractor was a mom and pop outfit known to me and he was an honest and qualified person who I had seen do excellent work in the past. In fact he did a good job at the site in question. But when it came to notes he was not the most diligent. The lawyer utterly crucified him on the stand and he lost ALL credibility and eventually the case because his notes were garbage, just some numbers jotted down on the front of the project file folder YIKES! I felt so bad for him watching it unfold and not being able to help him. On the other hand I can count two times when my note taking and standardized forms/process prevented charges or a court case and one time when my notes got a case dropped. Moral of the story, he with the best notes wins. Legal people like to see standardized approaches and standardized forms as they show you put thought into what you were doing even before you stepped foot on site. The alternative is a cowboy approach shooting from the hip. Regardless on how qualified you are, at that point, you run the risk of looking like an amateur.

    I run a national radon measurement and mitigation program in Canada for several banks, large commercial clients, government buildings, etc. When I have a site mitigated it is a requirement that I be provided the natural and post mitigation delta P across the slab. I use this data to ensure a good system installation but also to protect my firm and the mitigators that work for me.
  • Jeff Tikkanen
    How do we shift the US Paradym away from running vent pipe up the side of a house to a more cost-effective, better practice of direct venting at ground level? About 1/3 of our standards are based on the assumption we have to run our vent pipes above the roof line.

    If it is not necessary or advantageous to add 20-30 feet of pipe at the end of our air-flow systems, why do we continue to do so? Is this practice not somewhat insane?

    Are we so entrenched in our standard-writing process and the momentum of our industry's past practices that we cannot see and acknowledge the obvious?

    The new proposed standards suggest that we need better document our mitigation processes. The above posts quite effectively explain why. I would support the logic and science behind these proposals if only we were consistent in our logic and science regarding direct venting at ground level. I am sorry, but we cannot act logically on the one hand and illogically on the other.

    I challenge my fellow mitigation contractors and our standards writing committees to address this cornerstone issue once and for all. Please correct me if I am wrong, but if direct venting at ground level is best practice, it would be absurd to continue with our current practices.
  • Shawn Price
    While not a mitigator, I have been a supporter and worker bee on the standards since AARST's dream of the Consortium sprang to life. Standards Developer perspectives must also be considered in all of the work that gets published. Some of the considerations are the legal responsibilities and liabilities of the backing organization (AARST), who created audits to ensure adherence to the ANSI process, to ensure that the protection of the consumer are always in the forefront, and of course that the standards will do no harm to the organization, practitioners, or their clients.

    Part of the committee due diligence is to also understand related statutes and codes that may impact our work, as well as precedence set by other industries, standards, or codes. I am not on the MIT committee, but as an auditor for nearly all of the ANSI/AARST standards to date, I am aware that much of the work in the background included a review of work done by organizations, such as ASHRAE, who has published standards that definitely overlap with the radon mitigation industry. A quick Google search pulled up this document.


    I'm not a Mechanical Engineer either, but the details that I see in their document certainly suggests that significant research has gone into their exhaust criteria and moving in a direction different than theirs would need to be very well thought out, especially when one of their sections is titled Toxic Stack Exhausts. This one struck me and made me think. It certainly fits the definition, even if some people still think its only radon.
  • Jeff Tikkanen
    Thank you for the information, Shawn. I am not sure that we are comparing apples to apples when we compare exhausting combustible gas appliances with radon systems venting. However, it is interesting how similar the Canadian guidelines for venting radon systems at ground level are to guidelines for venting high efficiency water heaters and furnaces at ground level.
  • Bruce Decker BGIS
    Hi Jeff. I agree with you 100%. ASHRAE to residential radon isn’t apples to apples. The reason that the Canadian radon discharge clearances so closely match direct vent gas appliances is because the science of dispersion, re-entrainment and exposure are so very similar. With combustion appliance discharge we don’t see significant re-entrainment and we don’t see exceedance of acceptable carbon monoxide (CO) exposure limits indoors.

    Thanks for the input Shawn. I have also sat on several guideline and national standard committees here in Canada and I agree with your comments. But in these committees decision is by consensus and may not reflect all opinions or all science. In several cases I have seen over prescriptive measures introduced due to a lack of information, fear that the best method won't get implemented properly by trades or simply an overabundance of caution. These are all good intentions when protecting health but they can also become frustrating and excessive.

    It is essential to note the difference between ICI (Industrial, Commercial, Institutional) buildings and residential dwellings (i.e. houses). Industrial process exhaust and residential radon exhaust need to be looked at very differently. Yes, the attached ASHRAE document is sound environmental, mechanical, and building science engineering, but industry (i.e. residential building code) doesn’t use ASHRAE ICI standards of exhaust discharge for residential combustion appliances. Instead prescriptive clearances are provided that control adverse re-entrainment. One could try and apply the ASHRAE ICI standard to CO from combustion appliances in a residential setting as these effluents are technically covered by those standards but we don’t because those standards simply don’t apply to residential. It would be far too cumbersome, let alone unnecessary, for a mitigator to do all the math to apply ASHRAE ICI to residential.

    ICI discharges need and were developed to address point of impingement (e.g. fence line) exposures for a whole host of acutely toxic substances with short term exposure limits (STEL) and ceiling limits. This is vastly different to chronicly toxic substances with long-term weighted exposure limits such as radon. Even POI concentrations for chronicly acute substances are based on 24/7 365 70 year exposure risk base. I am not saying “its only radon”, I’m saying use proper industrial hygiene science and proper building science together.

    ASHRAE does mention radon in several of their standards but in my opinion these documents were never intended to deal specifically with radon but more so other acutely toxic substances. As a result they tend to confound things. The challenge, as Shawn has indicated, is that they may be general reference or even cited standards and therefore may have some legal bearing or perceived legal bearing.

    As we know, and as demonstrated by Bill Broadhead and Canada NRC we don’t see radon above the action level re-entraining into buildings at the action level at 6ft (2m). Furthermore even if we did see a spike of radon at the window face or a spike of radon re-entrain into the building at or above the action level, that does not mean weighted radon levels have been exceeded and that an overexposure has or will occur. If we are overly worried about a transient episodic re-entrainment of radon we misunderstand what an average weighted exposure limit is. For example, just because you have smelled second hand smoke a few times it doesn’t mean you have been overexposed and it doesn't mean you will get lung cancer from it, the same applies to radon. I am far less worried about a tiny episodic re-entrainment of radon then I am about a system icing up because of too much exterior piping and resulting in elevated indoor radon throughout the building for a number of days or weeks.

    Recently a few colleagues and I looked at an exhaust on a new construction radon system. Someone was using ASHRAE 62.1 2019 to impose a prescribed 30 ft (10m) minimum radon exhaust clearance criteria. Well this standard also permits you to calculate the required clearance instead of picking the 30 ft from the table. Well we did the math and came out with 6ft (2m) which is what the Canada NRC study and Bill Broadhead also figured out with experimentation.

    We need to make sure we don’t take the word “toxic” out of context especially without an associated exposure or dose component. As Paracelsus, the father of toxicology, said “Poison is in everything, and no thing is without poison. The dosage makes it either a poison or a remedy.” In other words the dose makes the poison. And yes radiation and radon have a no threshold dose limit but let’s put it in perspective for the goal of the mitigator, our industry and this thread.

    In the linked publication under the Toxic Stack Exhausts it clearly focuses on substances with rapid and acutely toxic effects (i.e. lab fume hoods and carbon monoxide from large output combustion appliances). These discharges are very different from a residential furnace, water heater or dryer or residential radon system. This takes us back to Jeff's comment above about the Canadian radon discharge clearance matching the gas appliance discharge clearance which matches Bill and NRC findings. Coincidence.......I think not. LOL
  • Shawn Price
    Good information Bruce. As you know, standard writing is very complex when trying to write a National standard, and is even more complicated when juggling and comparing proposed changes to statutes, codes, and regulations in the actual or tangential industries where there is overlap. Here in the US some states adopt the ANSI/AARST standards by reference, some use sections and insert it into their regulations, and some states have separate processes and maintain their own protocols. The problems are when the rules differ across states or are interpreted differently based on the industry use of similar technologies. Sometimes we get carried away and make things overly complex. Sometimes they may appear to be overbearing, but are based on sound committee arguments and experiences and might not have been explained to the users well enough. I don't have a dog in the mitigation standards fight since I am not involved in that type of work, but did want to point out that work outside of our industry directly influenced the original EPA protocols and standards since radon was new at the time. Many of those requirements have now been in the state regulations for years. Deciding to change the AARST standards to be different than the state laws can be a slippery slope and must be navigated carefully.
  • Doug Kladder
    I have been reading these posts and cannot agree more with the value of proper engineering, sizing of fans, area coverage as well as documentation. I also agree that changing a standard to what may be perceived as less stringent requires a cautious approach as Mr. Price has pointed out.

    However, I would like to turn the conversation back to the original posting made by Mr. Weestrand regarding one particular point and that is the extension of the exhaust point from 2 feet to 4 feet above an opening in a window. This is not as trivial adjustment. It essentially invalidates previous systems that had been installed by practitioners prior to the change. It also adds one or two rungs that an installer has to climb on a ladder that can already be too high when compared to Canadian experience and studies conducted in Canada as well as those referenced and conducted by Mr. Brodhead, Turk and Lewis.

    I echo Mr. Weestrand’s request for the data that the committee presented to justify raising the height of separation from an opening when the discharge is directed upwards. Presumably, there would be a preponderance of data and opinion that would cause the committee to make such a change and Mr. Weestrand’s request for that data to be shared is reasonable and in line with the transparency that characterizes this organization.

    Doug Kladder
  • Robert Mahoney
    Thanks for everyone’s input on this thread! I appreciate all of your experience! Being a newbie to radon mitigation, only 16 years in industry, however schooled by Arthur Scott and jack Bartholomew. I really don’t understand why you are afraid of validation, through simple math?? I literally know success and fan size in less than 10 minutes and validation of fan selection in less than 1 minute- yes I’m a indoor fan guy, with rim discharge, with only 4000 systems installed, but I guarantee less than 100 Bqm3 not our guidelines but WHO.
    Never had a failure!
    As Colin said, a little sealing goes a long way! Job today, RN 1 was way too strong! Got 46 pascals at furthest point, however didn’t change house pressure.0.0001 pascal- all things you need to know! So stop pushing back! Educate yourself! Do I write a book about every job- no, my test results are simply left on utube label, so anyone can duplicate my design!
    You need to know house negative pressure potential, fan required to draw 2.2 times that, to allow for variables of temperatures, wind etc, then a simple communication test- and fan selected!
    As Jack would say- know your PFE! Got the shirt!
    RIP my brother!
  • Daryl Festa
    I think that the discussion on the discharge line is a very important one. I also believe that an adoption of the Canadian design of the fan being on the interior of the home, not limited to un-occupiable areas, with a sidewall discharge could have a profoundly positive impact on the U.S. Radon market. Canada has demonstrated, through research and in practice, that Radon re-entrainment is not a danger with their design. There has been additional research in the U.S. to support and confirm this. It is my opinion, even absent this research, that a simple risk to benefit assessment would make adoption of this design a quite clear decision. Let’s look at the benefits:
    Aesthetics-There are many homeowners that elect not to have a radon system installed because it detracts from the appearance of their home.
    Sound-Neighbors complaining about noise from fans located on their side of the home would be greatly diminished.
    Effectiveness-The most effective radon systems have the fan as close to the slab penetration(s) as possible. If our goal is to create the lowest levels achievable, this would solve the problem.
    Electrical-Cost/Convenience-With the fan located inside, the issue of electricians and permits would be eliminated. The fan located indoors could simply be plugged in. It there is the concern of the fan being unplugged, this could be solved by putting a simple label stating “this plug operates a radon reduction system. Do not unplug!” and using a receptacle cover. This would save cost on most systems.
    Discharge ice-ups. With the elimination of discharge lines, most concerns with ice-ups, condensation, and ice related fan damage would be eliminated.
    Longevity of fans-Fan located indoors would be both protected from temperature extremes and large amounts of condensation. Both of these factors would lend to the fans lasting significantly longer.
    Air leakage from radon fans is governing the U.S. radon industry, prompting the current rules to prohibit fan installation inside habitable areas of homes. This is not and has never been an issue for high quality products assembled properly. Canada has implemented a simple soap test on the fan and connections to ensure no leakage from, and around the fan.
    Poor Installs/Violations-By simplifying radon system installs, many of the areas of cheating and violations would be eliminated, greatly evening the playing field.
    Worker Safety-In my 25 plus years of working with radon professionals I have seen and heard of many work-related injuries related to ladder falls. There have been broken backs, arms, legs, ribs, and concussions. Many systems are installed by one-man crews and involve propping a ladder on uneven ground with bricks etc. and no one to spot the worker. The CDC states that there are about 500,000 people treated and about 300 people die each year from ladder-related injuries. This danger would obviously be eliminated by eliminating the discharge line.
    When we have the opportunity to improve our industry with a simple and logical change, we have a responsibility to strongly consider it. The is magnified by the fact that our Canadian partners have undertaken the research and have over a decade of proven field experience to provide confidence in the proposed change for RADON MITIGATION SYSTEMS (not Vapor Intrusion VI which should not be our new industry focus governing all radon work). As a radon fan manufacturer and someone who has dedicated over 26 years of my life to the radon industry, I could not feel more strongly about the necessity for this change.
  • Randy Weestrand
    A good home builder will prevent springy floors by using joist spans well below code. His wall studs will never be 24” on center. His water supply will be copper, his siding cedar or cement and his basement fill will be clean crushed rock- even though cheaper alternatives meet code. The low and average quality builders meet code. He exceeds code and his reputation allows him to charge a premium price and thrive. This same environment exists in the radon industry.

    Where should the ‘code’ be in radon? As in home building, it should be the minimum required to provide a safe product for the consumer. Not a good product, but a safe product (think: Masonite siding). The ANSI AARST standards have left behind the idea of the minimum requirement for a safe product and are racing toward the minimum requirement for an outstanding product. I predict that if this doesn’t change, the end result will be states and municipalities rejecting the recent ANSI AARST standards. We did quite well under the EPA protocols. I’d vote to return to them. I could also live with ASTM E-2121-3 (with a minor revision).
  • Jeff Tikkanen
    Is there anyone out there in favor of keeping the current standards and adding the newly proposed standards for venting residential radon systems above the roof line? I would appreciate hearing a cogent scienced-based argument why we should continue this practice exclusively.

    Otherwise, I think we should begin defining the specific circumstances and site conditions where a radon contractor would be allowed to vent a residential radon system at or near ground level if they should choose to do so. For example, if there is an area on the side of a house where no doors, windows or nearby residences are present within 30 feet.

    Or maybe we might just adopt the Canadian guidelines.
  • Owen Reese
    Many here may already know this, but a big reason so many standards have been updated recently is due to NRPP becoming ISO accredited. ISO requires standards to be reviewed regularly and updated as needed. We can no longer rely on old EPA standards - doing so will prevent growth of the industry. ISO is widely recognized and accepted and lends legitimacy to all of us.

    I am not a mitigation specialist like many here, so I cannot weigh in on the merits of the proposed changes. I can say that NRPP does want and does listen to industry feedback. The goal of these standards is to find consensus - dissenting voices are critical. Please submit your criticisms via the link Dallas provided so they may be considered.

    As a Radon lab, I can also say that many here might be shocked at the number of post mitigation tests that fail. A failed test, of course, isn't fundamentally a sign of a failure to adhere to standards, but the high rate of failures I have observed seems to show a need for improvement.

    As is usually the case, the audience here on the listserv is not the likely culprit of these systems - we all know there are companies out there that do poor work, particularly in non-regulated states.

    It's my opinion that better standards strongly benefit the industry and those of us that do quality work. I also believe standards have been key to much of the growth we've seen recently - multifamily in particular. In the scope of a Laboratory standards, I've seen some things I disagree with, but the changes have been overwhelming positive, if not perfect. EPA standards were simply outdated and inadequate. I'd provide humble encouragement to not throw the baby out with the bathwater, and to please provide your expert opinions via the proper channels so we can all benefit from your experience and knowledge.
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