I did a Radon evacuation system in my house back in 2018. After working in my basement office for 8 years I discovered the 12pc/l levels. My house is old. Under the slab was an abandoned coal bin. I was able to tap into that. Due to low sill heights, installing pipe through the foundation to the outside was not going to be easy.. so I chose a different route. I also had an abandoned chimney. 4" PVC from the slab up 18" into the fan (I know. it's in a conditioned space (Where I can monitor it easily every day)) from the fan into the chimney with 4" PVC. Once in the chimney, I connected to triple wall drain pipe (Its lighter. I had to feed it down the chimney.). Levels went from 12 to an average of 1.7 since 2018. I know that having the fan in a condition space is not to code. That said. I believe it's better to be able to monitor something you can see every day, than live with a possibly dead radon fan that's in an attic you never go into.. I've heard horror stories of them freezing up from condensate.. Mine should last a long time.
Great review of Radon mitigation. I would love to see an even more in depth look at this topic, including a review of typical local codes, more 'aesthetic' installation ideas, the promise and pitfalls of do-it-yourself vs professional install (on existing homes), and radon mitigation in water (radon in water for homes with wells is just as big a concern).
something for Big Red some variables affecting the measurement of radon natural levels of radon, barometric pressure (falling pressure tends to increase the release of radon from soil with a time delay), location in house, accuracy of the measurement sensor ( multiple sensors sitting adjacent to each other do not read same measurement. what is the acceptable variance?) living space measurements can be affected by duct leakage (negative pressure in ducts relative to basement air pulls radon gas into the system from basement, negative pressure in living area compared to basement pulls radon into living area through cracks and vapor paths) for new construction consider improving sub slab air flow (but perhaps no longer passive) by replenishing air under the slab to increase the flow. that replenishing air could come from outdoors or the hrv or erv after careful pressure/flow calculations. consider edge placement of perforated pipe with "clean" to sweep the gasses to exhaust vent. could be edge to center flow or edge to edge depending on where exhaust is placed. use similar design criteria as is used for living space air flow but applied sub slab. why do vent pipes not get a rain cap? is it believed that air flow upwards is sufficient to keep water from going back down the stack? A simple "roof" over open end would seem to help. outdoor horizontal runs tend to condense moisture during cold temperatures and gurgle. a built in condensate release point or water trap point will solve the gurgling noise issue.
A pity Form-A-Drain doesn't sponsor this channel. Their system will mitigate Radon as well as groundwater when you pour the foundation for a new build. Their "capture points" are the entire perimeter as well as any foundation "beams" crossing under the basement slab floor.
@@stevenbaczekarchitect9431 How have they worked for your clients? I definitely intend to specify them if/when we build, especially since we want to go ICF (including ceilings) so it will be a VERY tight build.
I run Airthings sensors as well but the problem with this system is the humidity I believe drastically throws off the numbers. When talking with local Radon companies, humidity needs to be under like 50%. This can be difficulty in summer months, so best is to align with these sensors in the winter when humidity is lower. I get into 5s in Summer but in 2-3 in the Winter.
Hello Matt & Steve. Love the channel and all the content. I have a radon mitigation question that I am struggling with. I live in Maine in a 100+ year old house with a granite block foundation. I have a HRV air dilution system installed for radon mitigation due to an unsuitable basement slab for a traditional sub-slab system. For much of the year HRV provides adequate mitigation. However, I am experiencing periods of greater than the recommended levels. I am considering spraying a ~1' coat of closed cell spray foam on the basement ceiling between the floor joists to serve as a air barrier - thus preventing radon gas from migrating into the living space above. Also - the tighter basement envelope could allow the HRV to dilute and expel the radon gas more effectively due to the gas being contained and not mitigating out of the basement (upstairs). The literature I have read indicates that closed cell foam does provide a barrier against radon migration. My biggest concern is what spray foaming a Maine basement (8ft - full depth) ceiling will do with respect to humidity. Will I create an undesired increase in retained humidity in the basement? The humidity in the basement is already ~60-65. The basement temp is typically between 45 and 50. There are two forced air oil furnaces in the basement for winter heating. Are there any concerns with my approach that I haven't considered? Thank you for your time.
There was no mention of RadonSeal. I've used it in several basements in houses I've owned and applied it myself. Definitely seals the concrete to prevent leakage. It even fixed small cracks that leaked water. For an after built option...
Depressurizing the under-slab area either creates a problematic vacuum chamber down there, or there's an air intake for it that must be cut through or under the footing. Please explain what you've done.
The Airthings sensors you show are not approved for radon measurement by the National Radon Proficiency Program. Search NRPP approved devices if you'd like to see a list of devices you should use.
For older homes without poly below the slab, what options are there for radon mitigation to ensure radon is escaping only from the pit by the radon mitigation system? Is a roll on water barrier or concrete sealer the solution?(along with caulking joints and cracks)
You'd be amazed to hear how many real-estate professionals will tell customers that Radon is only an issue in homes with basements. It will accumulate more in a basement, but you are still at risk on a slab if it's coming up through concrete and cracks
I bought a great Radon detector on Amazon, it shows short term average over a week and long term average. I built my new house by Pikes Peak in Colorado, lots of granite & Radon. Under my downstairs radiant slab, in the crushed gravel layer, I put 40’ of perforated 4” ABS warped with polypropylene land scraping fabric, the 4” ABS exits about 24” above my roof peak, the slight vacuum created by wind reduced my Radon to about 2 pico-curries. The ABS pipe goes up in my boiler room in a 24” chase where I put an 120V outlet in case I needed an air pump.
Like the detailed explanation, great video. Do you know if you can use the black corrugated pipes with holes put it under the (gravel+6mm poly+4" concrete) and take the pipe out of the house to mitigate radon gas? Radon is 7-8 times heavier than air so will it settle in the pipe and exhaust out of Nudura ICF house in East TN or you need a fan to suck the air into the corrugated pipe?
Phoenix, AZ here. I've never heard of Radon.. I'll have to look into this. Radon sensors too? Looked like AZ is one of those zones where it's non existent for the most part 〽️ AZ native so I've never lived anywhere else and own multiple houses and never seen/heard of it.
Steven Baczek Architect Question could you just run the exhaust tube straight out under the foundation wall before pouring like the water drainage then straight up the outside foundation wall and skip having 2 more penetrates into your air barrier?
Theoretically - what you lose is the stack effect movement of the air because it is heated inside. You situation would require a mechanically induced flow (fan)
My understanding is that even in states with very high ambient radon levels, the outdoor levels rarely exceed .5 pci/li. So 4 is probably too much, particularly when you consider that homes prior to 1950 or so didn't have central air and generally didn't have habitable basements, so the levels were typically much lower. Nice thing about the airthings meters is they can be used over a much longer time span, while other methods only sample over 24 hours or so. In my experience variations in weather can alter levels by as much as 3 fold. So a reading of 4 on a high pressure series of days could be 12 when a low pressure system moves in.
I also have my fan in the basement. Seems like they do it that way in Canada. No ugly pipe outside, just an exhaust vent where people don't populate. The fan should last longer as well not being outside.
8:12 It could be the camera angle. But is there something to block rain from going down that pipe? Either an upside down U or some sort of cap that blocks rain, but allows the flow of air?
The drain tile installed around the internal and external perimeter of the footings is connected. Why can't these pipes be used to also collect radon gas? My plan was to use the sump pump crock as the collection point. I plan to seal the lid and add a vent pipe connected to the radon vent stack. In addition, the expansion joint around the slab perimeter will be caulked and there will be a 6-10 mil plastic under the slab.
Another great episode. I understand that it's always best to design with a belt and suspenders approach, but I wonder how much radon can get past a taped 15 mil Stego barrier, and if then sealing the slab with a viscous coating wouldn't be a safe enough detail.
@@stevenbaczekarchitect9431 You're right of course.... Just that the market overwhelmingly votes against spending money on the dark side of the sheetrock, so the natural inclination is try to pacify the market forces, as uninformed as they might be.
@@andrewfalkenstein3071 Agreed - I remind clients the cost of fixing somethin on the darkside of the sheetrock after it is completed........most understand this concept
Steve, should the under floor perforated pipe be extended via branching to the far corners of the home to provide an easier path for any radon to be captured and ejected.
Hey Steve, what's your thoughts on utilizing the below slab water drainage and radon mitigation piping into one system if you are able to simply daylight your water drains on a sloping site rather than using a sump pit?
It will work but not as well because 1) the drain pipe can be full of water which will restrict the air movement 2) you'll have no stack effect ensuring some air movement since the drain exit point is lower than the pipe itself
@@muchmuchmore obviously. I meant having the daylight drain for water and the stack through the roof for the radon, just combining all the piping together into one system.
The radon in the previous house was not so high but the house was poorly built so I think it was always ventilating, now we have put a new build and didn´t concern with the radon. Its well sealed and we tiled throughout and just read that tiles emit radiation.... sitting in my office now with a reading of 151mBq. have to see if ventilation will be enough to lower it.
I checked, and supposedly Lead is the long term decay product. Do you have to worry about lead dust buildup in the soil around your house long term, or no?
Shouldn't you also have supply air? Otherwise you are sucking on a straw with your finger on the end. Ideally situated in the gravel as far from the exhaust stack as possible so fresh air is can be drawn through the gravel displacing any radon rich air. I have read that in time, without a fresh air source, dirt etc will get pulled into the gravel from any existing air sources under the foundation and the efficiency of the mitigation drops significantly. You could probably use the perimeter drain pipe if it day lighted some place.
Does the AprilAire fan run continuously or on a schedule? Would the fan essentially create a vacuum under your house since it is adding suction to an enclosed cavity?
@@Rickmakes Why would you want negative pressure? Won't this system draw air from sump pit and from seam between concrete floors and walls thus creating negative pressure in the basement.
@@rhondalemmon3076 Yes, it would draw air from those locations. These are also the areas where radon enters the home. I'm no expert in this but I'm guessing there are situations where they would caulk the seams to increase efficiency.
@@rhondalemmon3076 what needs to be done is to seal off all of those areas. The retrofit in this video talked about sealing the gap between the slab and the foundation. The new build will have 4” of closed cell foam with the Stego on top of it. My experience - in our ~25 year old home, we sealed that gap and added a fan to the passive vent which the builder installed (code reqt here) and the numbers went from 25 to just below 2.
Confirmed. You want a slightly negative pressure under the slab. A part of radon mitigation should be using radon sealant on any perforations on your 10mil vapor barrier. This barrier should be run up the side of the foundation wall and be radon sealed to the wall. No air should be allowed through. The sump pit should also be sealed. The radon fan will pull air from under the slab up through the sump to a few feet above the roof
What about the foundation walls? Soil are on the outside of these walls and radon can come in through them. I was thinking installing a floating floor that has water gap membrane so that it can use as a way for the air to be suck by the ventilation system, that way no need to break into the concrete slab.
I found this channel looking for ideas for designing my next house. It's been a great help but I'd love to see something about your opinion on these green planted roofs. I like the idea but I can also see how it could be a complete nightmare
Planted roofs are a scam. A white roof reflects the heat better and is better for the planet. TH-cam search for: “building science lecture white roof”.
@@pl2604 I'm not interested in planted roofs for those particular reasons. I really just like the look and the idea of having a flower garden/picnic area set up on my roof
Hey Matt I am a builder in Michigan. Going to build my final home this spring. Trying to figure out the best bath fan. On with the best energy rating. Witch one do you recommend?
Perhaps I didnt understand but are ypu using 2 layers of Stego? I understand the 1st layer covering the pipe and gravel. Are you spray foaming an underslab insulation layer on top of the first layer Stego and adding another Stego layer on top of the foam? before pouring the floor or did I misinterpret this? Is it difficult to get a consistent foam thickness given the way foam expands? Or can you get close enough you don't have shallow spots in your concrete?
It is a single layer of 15 mil Stego Home over 4” of low VOC spray foam (Natural Polymers’ Ultra Pure). The Stego installation instructions call for an overlap of what I recall is 6-8” wherever two pieces meet. The taping of the joints and sealing about 6” up the wall of the foundation are important elements of that installation. Concrete is then poured on top of the Stego. They advise to be cautious about walking on the Stego after installation and before concrete is poured, but that material is really tough! I would be more worried about not pulling the seams apart or the taped Stego from the walls. I think all it takes is being aware and careful on those issues.
Passive radon mitigation in new build should be mandatory based on county findings. Nebraska doesn't require it but every other home in Omaha has an active system... same with Ohio... Indiana and Illinois...
@spurly48 did you have to request it, or was it mandated? Or builder recommended? When I moved into the area in 2016 the house to the left and right of the one I bought had active systems, told the real estate agent it had radon before we tested and he asked me how was I sure?...
@@persistentwind I believe as of 2019, all new construction in Nebraska requires at least a passive system. LB130 made the change to the local building code.
Maybe a stupid question, but why do you need venting at all? Why not just seal the slab/walls with Stego or whatever to block the radon, just like we do for water? Or use the sump pit as the radon collector?
There are systems that use the sump as a collection point, since it connects to the slab gravel as well. Just sealing isn’t usually enough (or at least recommended) because radon can permeate through slowly, and heating a home in winter will create the “stack effect”. Which just means the hot air inside will rise up and out of the home, creating a vacuum against the slab which pulls radon up. That’s the principle of a passive radon system, active will use a fan to create a constant vacuum on the gravel bed.
Pier and beam, if it has a ventilated perimeter so air can move through will vent out the radon in the air gap between the ground and the floor ... BUT then you've got the humidity / moisture problem under the house and the floor has to be well insulated. If the owner later closes off the airspace we all know the humidity will go high and potentially rot starts developing but the other problem is that the radon gets trapped too
can you angle the exhaust, seems like a big exhaust pipe seems like a rain catcher like that, condensation and rain drops going down to the electric motor?
Nope, with the fan on you will not get very much rain down the pipe and if so it is required to be pitched back to the entry point and the ground will soak it up.
We use them and they are decent for mitigation. We generally only expect them to remove 50% of the radon where as an ASD system as Steve is doing here can be 99% efficient. The main problem with the HRV/ERV for radon is you are attacking the already contaminated basement air and not below the slab. They need to be balanced perfectly.
experience has shown with a friend's house that it should be dealt with at the level where it is coming into the house, not pulling it up into the living spaces where an ERV will typically address air issues. It will depend upon the design of the ERV system. Once the seasons changed and the heating system was active, it simply brought the radon from the basement to the living spaces.
Venting above the roofline allows the radon to be diluted to a safe level as it falls & even small breezes disperse it. Sending it downhill could allow it to collect at a downhill spot on your or a neighbor’s yard.
Steve - wondering about the stack pipe that has holes in it. Shouldn't the pipe be solid to ensure radon does not migrate into the house? Thanks for all you do
absolutely correct. Steve mentioned that the pipe with holes was just a mock-up using a pipe that was at the site and that you would never use a vertical pipe above the slab that has holes.
Yes to both below - understand 40-50 years ago the wind blew threw them. I grew up in a house with a dirt floor in the basement and we never had mold problems or the like, it also cost a bunch to stay warm in the winter
The old houses usually didn't sit on the ground like today. Plus people died of lung cancer all the time from the 30s -70s but we assumed it was all from smoking
How many feet apart should the perforated pipe lines be? I assume there is a "tree" of pipes down there or a series of "H"s or something. Basically what is the max recommended pipe to pipe distance to have an effective radon mitigation system?
@@stevenbaczekarchitect9431 Thanks. Yes but two, how long is the horizontal part of each? Is there any branching/ Tees in the horizontal part or just a long straight run?
@@stevenbaczekarchitect9431 wow. I know nothing about radon but that is just not a lot of pipe length for a large house. I'm guessing the gravel is the key, not the pipe. The gravel makes like a big plenum under the house. Ok thanks for the tip!
I think this is overkill. A layer closed cell foam with a sealed vapor barrier above that should be more than enough to block any radon transmission, without the need for a venting system.
While the Stego mat and the closed foam insulation might solve some radon problems, I would not want to take that risk when the cost is so small to put in a system at the time of construction. A retrofit presents a lot more challenges, costs and uncertainty of success. Using all three together (foam, Stego, AprilAire fan) means that it is virtually certain that you will not have a problem. A passive system is a requirement in a number of counties in Massachusetts, for good reason. Good question!
I don't think you are appreciating the risk of it getting into the house. Think of every person you've heard who's died of lung cancer and didn't smoke. It's almost always Radon or Natural gas leaks
@@Nitrobucket Everything in home design/construction involves a choice or a trade off. If you try to designed and build every home to the highest safety standard, even when the risk is low, every house would cost a million dollars. Obviously, the local building code rules the day, but aside from that, some common sense needs to be applied.
Since it is a new build why wouldn't you put the pipe in the stone and take it to the Perimeter of the house along with putting Perimeter pipe around the foundation like your drain, so you aren't sucking in gas from the surrounding land?
The drain tile is on the perimeter, but it has to come inside to get to the sump pump. You can't have the sump pump outside because it could freeze up in the winter since it has to have an access cover.
Im a licensed radion specialist. The EPA guidance for radon is a measurement of 4 piCU/L; any higher and it requires mitigation. Every real estate transaction should include a radon test. A short 6 min sampling is not very accurate. I run a minimum 48 hour continuous radon monitor. Weather impacts radon levels. New construction passive systems are worthless. Radon is 7.5 times heavier that air. Radon will not rise in a passive system. The problem is that realtors convice buyers to waive home inspections and radon testing so they reduce impediments to their commission.
The 6 minute test mentioned was with the professional-level monitoring device shown and costing several thousand dollars. The mitigation company brought that to test each location and the results were almost identical to the AirThings ViewPlus devices that had been in place for more than a week.
I'm glad these build show videos are being published to youtube more consistently because the build show website sucks! I don't know who designed the layout on that site, but they did a sh*tty job.
@@stevenbaczekarchitect9431 I was trying to give you a compliment and reiterate what you said was correct. As I have been studying to get my radon mitigation license for Illinois, I know all about radon in the effects of it from all the studying and research I have done. I was telling someone in the comments to do there own research because they said radon was a myth. Why you so upset that I told someone it's not a myth?
I would have to disagree, based on the science. Is there research that you can point to that debunks all of the science that has been out for many years. The research I have seen supports the dangers of radon and that it is the leading cause of lung cancer deaths among non-smokers? If you have any research data that you believe debunks this, please help everyone by providing that material. Would you want your family, including young children, to live in a house that had elevated radon levels without addressing the issue? It is pretty straightforward to mitigate the radon in an existing house and even easier to do so with a home being built.
Its like Jan 6: one more thing to scare home owners into buying multiple $250 gadgets. Level 16 radon. Give me a break. Unless you actually live in the basement, who cares.
I did a Radon evacuation system in my house back in 2018. After working in my basement office for 8 years I discovered the 12pc/l levels. My house is old. Under the slab was an abandoned coal bin. I was able to tap into that. Due to low sill heights, installing pipe through the foundation to the outside was not going to be easy.. so I chose a different route. I also had an abandoned chimney. 4" PVC from the slab up 18" into the fan (I know. it's in a conditioned space (Where I can monitor it easily every day)) from the fan into the chimney with 4" PVC. Once in the chimney, I connected to triple wall drain pipe (Its lighter. I had to feed it down the chimney.). Levels went from 12 to an average of 1.7 since 2018. I know that having the fan in a condition space is not to code. That said. I believe it's better to be able to monitor something you can see every day, than live with a possibly dead radon fan that's in an attic you never go into.. I've heard horror stories of them freezing up from condensate.. Mine should last a long time.
good story
Great review of Radon mitigation. I would love to see an even more in depth look at this topic, including a review of typical local codes, more 'aesthetic' installation ideas, the promise and pitfalls of do-it-yourself vs professional install (on existing homes), and radon mitigation in water (radon in water for homes with wells is just as big a concern).
Thanks for the video on radon detection. We have bought a test kit from Home Depot, $18+ and well worth it 👌
That's how to do it - Great to know you mitigated the problem so early, now keep on monitoring!
something for Big Red
some variables affecting the measurement of radon
natural levels of radon, barometric pressure (falling pressure tends to increase the release of radon from soil with a time delay), location in house, accuracy of the measurement sensor ( multiple sensors sitting adjacent to each other do not read same measurement. what is the acceptable variance?) living space measurements can be affected by duct leakage (negative pressure in ducts relative to basement air pulls radon gas into the system from basement, negative pressure in living area compared to basement pulls radon into living area through cracks and vapor paths)
for new construction consider improving sub slab air flow (but perhaps no longer passive) by replenishing air under the slab to increase the flow. that replenishing air could come from outdoors or the hrv or erv after careful pressure/flow calculations. consider edge placement of perforated pipe with "clean" to sweep the gasses to exhaust vent. could be edge to center flow or edge to edge depending on where exhaust is placed. use similar design criteria as is used for living space air flow but applied sub slab.
why do vent pipes not get a rain cap? is it believed that air flow upwards is sufficient to keep water from going back down the stack? A simple "roof" over open end would seem to help.
outdoor horizontal runs tend to condense moisture during cold temperatures and gurgle. a built in condensate release point or water trap point will solve the gurgling noise issue.
A pity Form-A-Drain doesn't sponsor this channel. Their system will mitigate Radon as well as groundwater when you pour the foundation for a new build. Their "capture points" are the entire perimeter as well as any foundation "beams" crossing under the basement slab floor.
I have it on a couple projects at the moment
I'd never heard of that, but it looks like a no-brainer: a concrete form that's also a drain!
@@stevenbaczekarchitect9431 How have they worked for your clients? I definitely intend to specify them if/when we build, especially since we want to go ICF (including ceilings) so it will be a VERY tight build.
@@stevenbaczekarchitect9431 I hope you guys can talk about it on a future episode, sounds interesting!
@@michiganengineer8621Did you ever build this? Any documentation of it? Would love to watch a video on this.
I run Airthings sensors as well but the problem with this system is the humidity I believe drastically throws off the numbers. When talking with local Radon companies, humidity needs to be under like 50%. This can be difficulty in summer months, so best is to align with these sensors in the winter when humidity is lower. I get into 5s in Summer but in 2-3 in the Winter.
This, also you have to reset them and let the sensors recalibrate for 7 days in the new area you move them to.
So put a dehumidifier down there. All that humidity crates mold.
Hello Matt & Steve. Love the channel and all the content. I have a radon mitigation question that I am struggling with. I live in Maine in a 100+ year old house with a granite block foundation. I have a HRV air dilution system installed for radon mitigation due to an unsuitable basement slab for a traditional sub-slab system. For much of the year HRV provides adequate mitigation. However, I am experiencing periods of greater than the recommended levels. I am considering spraying a ~1' coat of closed cell spray foam on the basement ceiling between the floor joists to serve as a air barrier - thus preventing radon gas from migrating into the living space above. Also - the tighter basement envelope could allow the HRV to dilute and expel the radon gas more effectively due to the gas being contained and not mitigating out of the basement (upstairs). The literature I have read indicates that closed cell foam does provide a barrier against radon migration. My biggest concern is what spray foaming a Maine basement (8ft - full depth) ceiling will do with respect to humidity. Will I create an undesired increase in retained humidity in the basement? The humidity in the basement is already ~60-65. The basement temp is typically between 45 and 50. There are two forced air oil furnaces in the basement for winter heating. Are there any concerns with my approach that I haven't considered? Thank you for your time.
A few of my prior homes, in central Ohio, central NC and Indiana, we had radon mitigation in those 4 homes wherein we had walk-out basements
Even in walkout basements, it’s really important?
There was no mention of RadonSeal. I've used it in several basements in houses I've owned and applied it myself. Definitely seals the concrete to prevent leakage. It even fixed small cracks that leaked water. For an after built option...
Depressurizing the under-slab area either creates a problematic vacuum chamber down there, or there's an air intake for it that must be cut through or under the footing. Please explain what you've done.
The Airthings sensors you show are not approved for radon measurement by the National Radon Proficiency Program. Search NRPP approved devices if you'd like to see a list of devices you should use.
He may be false readings from an uncalibrated device
While not calibrated or approved, the Airthings and better Ecosense devices are cheap and indicative, allowing for better measurements afterward.
For older homes without poly below the slab, what options are there for radon mitigation to ensure radon is escaping only from the pit by the radon mitigation system? Is a roll on water barrier or concrete sealer the solution?(along with caulking joints and cracks)
You'd be amazed to hear how many real-estate professionals will tell customers that Radon is only an issue in homes with basements. It will accumulate more in a basement, but you are still at risk on a slab if it's coming up through concrete and cracks
I bought a great Radon detector on Amazon, it shows short term average over a week and long term average.
I built my new house by Pikes Peak in Colorado, lots of granite & Radon.
Under my downstairs radiant slab, in the crushed gravel layer, I put 40’ of perforated 4” ABS warped with polypropylene land scraping fabric, the 4” ABS exits about 24” above my roof peak, the slight vacuum created by wind reduced my Radon to about 2 pico-curries.
The ABS pipe goes up in my boiler room in a 24” chase where I put an 120V outlet in case I needed an air pump.
Wow, you guys are legit informative. Subbed!
Great work Steve!
Thank you!!!
Like the detailed explanation, great video.
Do you know if you can use the black corrugated pipes with holes put it under the (gravel+6mm poly+4" concrete) and take the pipe out of the house to mitigate radon gas? Radon is 7-8 times heavier than air so will it settle in the pipe and exhaust out of Nudura ICF house in East TN or you need a fan to suck the air into the corrugated pipe?
Phoenix, AZ here. I've never heard of Radon.. I'll have to look into this. Radon sensors too? Looked like AZ is one of those zones where it's non existent for the most part 〽️ AZ native so I've never lived anywhere else and own multiple houses and never seen/heard of it.
Ya with low humidity and no basements it's a non-issue here.
Steven Baczek Architect
Question could you just run the exhaust tube straight out under the foundation wall before pouring like the water drainage then straight up the outside foundation wall and skip having 2 more penetrates into your air barrier?
Theoretically - what you lose is the stack effect movement of the air because it is heated inside. You situation would require a mechanically induced flow (fan)
Love this series. Not sure if you answer questions. Is Radon only an issue in a home with a basement or is a house on a slab equally at risk?
Thanks
Both
We have to put mitigation systems in homes on slabs here - State Building Code
My understanding is that even in states with very high ambient radon levels, the outdoor levels rarely exceed .5 pci/li. So 4 is probably too much, particularly when you consider that homes prior to 1950 or so didn't have central air and generally didn't have habitable basements, so the levels were typically much lower. Nice thing about the airthings meters is they can be used over a much longer time span, while other methods only sample over 24 hours or so. In my experience variations in weather can alter levels by as much as 3 fold. So a reading of 4 on a high pressure series of days could be 12 when a low pressure system moves in.
great points - thank you
Can you explain why the fan should not be within the condition space? My fan pipe is 4 feet above the slab hole and it works like a charm.
I also have my fan in the basement. Seems like they do it that way in Canada. No ugly pipe outside, just an exhaust vent where people don't populate. The fan should last longer as well not being outside.
Radon is everywhere… the “low risk” regions are low risk only because houses over in the south tend to not have a basement…
8:12 It could be the camera angle. But is there something to block rain from going down that pipe? Either an upside down U or some sort of cap that blocks rain, but allows the flow of air?
Nope. What little water enters will simply end up under the slab
The drain tile installed around the internal and external perimeter of the footings is connected. Why can't these pipes be used to also collect radon gas? My plan was to use the sump pump crock as the collection point. I plan to seal the lid and add a vent pipe connected to the radon vent stack. In addition, the expansion joint around the slab perimeter will be caulked and there will be a 6-10 mil plastic under the slab.
Another great episode. I understand that it's always best to design with a belt and suspenders approach, but I wonder how much radon can get past a taped 15 mil Stego barrier, and if then sealing the slab with a viscous coating wouldn't be a safe enough detail.
The challenge here always is, you ONLY get 1 shot at this.....
@@stevenbaczekarchitect9431 You're right of course.... Just that the market overwhelmingly votes against spending money on the dark side of the sheetrock, so the natural inclination is try to pacify the market forces, as uninformed as they might be.
@@andrewfalkenstein3071 Agreed - I remind clients the cost of fixing somethin on the darkside of the sheetrock after it is completed........most understand this concept
An architect on the job site wearing flannel 👍👍
Thank you - it was cold that day!!!
Steve, should the under floor perforated pipe be extended via branching to the far corners of the home to provide an easier path for any radon to be captured and ejected.
We use the 3/4 stone pad
Hey Steve, what's your thoughts on utilizing the below slab water drainage and radon mitigation piping into one system if you are able to simply daylight your water drains on a sloping site rather than using a sump pit?
It will work but not as well because 1) the drain pipe can be full of water which will restrict the air movement 2) you'll have no stack effect ensuring some air movement since the drain exit point is lower than the pipe itself
I like to keep them seperate
The radon containing air doesn't run downhill like water
@@muchmuchmore obviously. I meant having the daylight drain for water and the stack through the roof for the radon, just combining all the piping together into one system.
The radon in the previous house was not so high but the house was poorly built so I think it was always ventilating, now we have put a new build and didn´t concern with the radon. Its well sealed and we tiled throughout and just read that tiles emit radiation.... sitting in my office now with a reading of 151mBq. have to see if ventilation will be enough to lower it.
I checked, and supposedly Lead is the long term decay product. Do you have to worry about lead dust buildup in the soil around your house long term, or no?
not familiar with it
Probably not, the actual amount (mass) is down in the picograms area
Shouldn't you also have supply air? Otherwise you are sucking on a straw with your finger on the end. Ideally situated in the gravel as far from the exhaust stack as possible so fresh air is can be drawn through the gravel displacing any radon rich air. I have read that in time, without a fresh air source, dirt etc will get pulled into the gravel from any existing air sources under the foundation and the efficiency of the mitigation drops significantly. You could probably use the perimeter drain pipe if it day lighted some place.
Does the AprilAire fan run continuously or on a schedule? Would the fan essentially create a vacuum under your house since it is adding suction to an enclosed cavity?
It runs continuously to create negative pressure under the slab.
@@Rickmakes Why would you want negative pressure? Won't this system draw air from sump pit and from seam between concrete floors and walls thus creating negative pressure in the basement.
@@rhondalemmon3076 Yes, it would draw air from those locations. These are also the areas where radon enters the home. I'm no expert in this but I'm guessing there are situations where they would caulk the seams to increase efficiency.
@@rhondalemmon3076 what needs to be done is to seal off all of those areas. The retrofit in this video talked about sealing the gap between the slab and the foundation. The new build will have 4” of closed cell foam with the Stego on top of it.
My experience - in our ~25 year old home, we sealed that gap and added a fan to the passive vent which the builder installed (code reqt here) and the numbers went from 25 to just below 2.
Confirmed. You want a slightly negative pressure under the slab. A part of radon mitigation should be using radon sealant on any perforations on your 10mil vapor barrier. This barrier should be run up the side of the foundation wall and be radon sealed to the wall. No air should be allowed through. The sump pit should also be sealed. The radon fan will pull air from under the slab up through the sump to a few feet above the roof
I would cover that stone with poly prior to pouring the slab!
Exactly the plan - did you watch the "mock up" portion?
What about the foundation walls? Soil are on the outside of these walls and radon can come in through them. I was thinking installing a floating floor that has water gap membrane so that it can use as a way for the air to be suck by the ventilation system, that way no need to break into the concrete slab.
Excellent information and not code in all areas.The problem is random samples must be made in all areas
Agreed
I found this channel looking for ideas for designing my next house. It's been a great help but I'd love to see something about your opinion on these green planted roofs. I like the idea but I can also see how it could be a complete nightmare
Planted roofs are a scam. A white roof reflects the heat better and is better for the planet. TH-cam search for: “building science lecture white roof”.
@@pl2604 I'm not interested in planted roofs for those particular reasons. I really just like the look and the idea of having a flower garden/picnic area set up on my roof
If you have an insulated foam slab foundation do you still get radon?
Yes, you can still have elevated radon levels and should test.
Hey Matt I am a builder in Michigan. Going to build my final home this spring. Trying to figure out the best bath fan. On with the best energy rating. Witch one do you recommend?
Perhaps I didnt understand but are ypu using 2 layers of Stego? I understand the 1st layer covering the pipe and gravel. Are you spray foaming an underslab insulation layer on top of the first layer Stego and adding another Stego layer on top of the foam? before pouring the floor or did I misinterpret this? Is it difficult to get a consistent foam thickness given the way foam expands? Or can you get close enough you don't have shallow spots in your concrete?
It is a single layer of 15 mil Stego Home over 4” of low VOC spray foam (Natural Polymers’ Ultra Pure). The Stego installation instructions call for an overlap of what I recall is 6-8” wherever two pieces meet. The taping of the joints and sealing about 6” up the wall of the foundation are important elements of that installation. Concrete is then poured on top of the Stego. They advise to be cautious about walking on the Stego after installation and before concrete is poured, but that material is really tough! I would be more worried about not pulling the seams apart or the taped Stego from the walls. I think all it takes is being aware and careful on those issues.
Orders radon test kit!
Passive radon mitigation in new build should be mandatory based on county findings. Nebraska doesn't require it but every other home in Omaha has an active system... same with Ohio... Indiana and Illinois...
Our new build (2022) in Gretna has a passive system.
@spurly48 did you have to request it, or was it mandated? Or builder recommended? When I moved into the area in 2016 the house to the left and right of the one I bought had active systems, told the real estate agent it had radon before we tested and he asked me how was I sure?...
@@persistentwind I believe as of 2019, all new construction in Nebraska requires at least a passive system. LB130 made the change to the local building code.
@@spurly48 that's great to hear!
Radon is a great topic. Steve - could you move your microphone 4 inches lower please? It often overloads when you tilt your head down or get excited.
Will work on it - I am sorry, just tooooo excited to talk shop
My continuous radon reading average was 3.4 with it going up to 3.9 occasionally.. should I bother installing a radon mitigation?
Yes. You need that number to be in the 1s or lower
How does radiation that just goes through the earth no big deal get somehow trapped and fully contained by plastic and concrete?
"It gets Contained" is meant to be only the portion that would challenge the home's footprint...
Maybe a stupid question, but why do you need venting at all? Why not just seal the slab/walls with Stego or whatever to block the radon, just like we do for water? Or use the sump pit as the radon collector?
I would imagine that radon can slowly go through concrete. But also over time concrete can have micro fractures and radon will go through them.
There are systems that use the sump as a collection point, since it connects to the slab gravel as well.
Just sealing isn’t usually enough (or at least recommended) because radon can permeate through slowly, and heating a home in winter will create the “stack effect”. Which just means the hot air inside will rise up and out of the home, creating a vacuum against the slab which pulls radon up. That’s the principle of a passive radon system, active will use a fan to create a constant vacuum on the gravel bed.
Is this a bigger problem for homes with basements and what about homes with a pier and beam foundation that is ventilated?
Pier and beam, if it has a ventilated perimeter so air can move through will vent out the radon in the air gap between the ground and the floor ...
BUT then you've got the humidity / moisture problem under the house and the floor has to be well insulated. If the owner later closes off the airspace we all know the humidity will go high and potentially rot starts developing but the other problem is that the radon gets trapped too
can you angle the exhaust, seems like a big exhaust pipe seems like a rain catcher like that, condensation and rain drops going down to the electric motor?
Nope, with the fan on you will not get very much rain down the pipe and if so it is required to be pitched back to the entry point and the ground will soak it up.
@@kylekelley213 TY, was wondering, i live in Wa, so it rains half the year : ) was curious if you should put a rain cap or something on it
I read a study that purported with a tight house, an ERV is effectively radon mitigation. Does anyone know whether this is true?
It will help, but only when it's running. It may not be enough to fully lower levels.
It probably has some positive effect, I wouldn't rely on it
We use them and they are decent for mitigation. We generally only expect them to remove 50% of the radon where as an ASD system as Steve is doing here can be 99% efficient. The main problem with the HRV/ERV for radon is you are attacking the already contaminated basement air and not below the slab. They need to be balanced perfectly.
experience has shown with a friend's house that it should be dealt with at the level where it is coming into the house, not pulling it up into the living spaces where an ERV will typically address air issues. It will depend upon the design of the ERV system. Once the seasons changed and the heating system was active, it simply brought the radon from the basement to the living spaces.
At 1:55 not thrilled seeing those protruding bricks. It looks like oversized clothes.
Radon is seven times heavier than air. Why are you venting it above the roofline instead of sending it downhill with the drain?
Venting above the roofline allows the radon to be diluted to a safe level as it falls & even small breezes disperse it. Sending it downhill could allow it to collect at a downhill spot on your or a neighbor’s yard.
How did it become customary that these videos need stock footage of a person coughing, or acting out frustration?
Steve - wondering about the stack pipe that has holes in it. Shouldn't the pipe be solid to ensure radon does not migrate into the house? Thanks for all you do
absolutely correct. Steve mentioned that the pipe with holes was just a mock-up using a pipe that was at the site and that you would never use a vertical pipe above the slab that has holes.
Tropical guy here and I had no idea Radon was an issue. This was interesting but I wonder what people did 40-50 years ago?
Died much younger.
Houses also weren’t built as tight as they are now.
Yes to both below - understand 40-50 years ago the wind blew threw them. I grew up in a house with a dirt floor in the basement and we never had mold problems or the like, it also cost a bunch to stay warm in the winter
The old houses usually didn't sit on the ground like today. Plus people died of lung cancer all the time from the 30s -70s but we assumed it was all from smoking
How many feet apart should the perforated pipe lines be? I assume there is a "tree" of pipes down there or a series of "H"s or something. Basically what is the max recommended pipe to pipe distance to have an effective radon mitigation system?
We have 2 for about 3000 sq ft of slab
@@stevenbaczekarchitect9431 Thanks. Yes but two, how long is the horizontal part of each? Is there any branching/ Tees in the horizontal part or just a long straight run?
@@SwordOfLaban2 8' straight pipe in 10" stone bed of 3/4" stone
@@stevenbaczekarchitect9431 wow. I know nothing about radon but that is just not a lot of pipe length for a large house. I'm guessing the gravel is the key, not the pipe. The gravel makes like a big plenum under the house. Ok thanks for the tip!
@@SwordOfLaban2 yes correct
I wish you had done a "big red" on the radon system design!
We can catch up on it when we look at the slab assembly
ive been monitoring mine for a while, highest ive gotten is 3.6 im ok with those numbers, but not ok with those numbers : /
I think this is overkill. A layer closed cell foam with a sealed vapor barrier above that should be more than enough to block any radon transmission, without the need for a venting system.
State Building Code requirement here
While the Stego mat and the closed foam insulation might solve some radon problems, I would not want to take that risk when the cost is so small to put in a system at the time of construction. A retrofit presents a lot more challenges, costs and uncertainty of success. Using all three together (foam, Stego, AprilAire fan) means that it is virtually certain that you will not have a problem. A passive system is a requirement in a number of counties in Massachusetts, for good reason. Good question!
I don't think you are appreciating the risk of it getting into the house. Think of every person you've heard who's died of lung cancer and didn't smoke. It's almost always Radon or Natural gas leaks
@@Nitrobucket Everything in home design/construction involves a choice or a trade off. If you try to designed and build every home to the highest safety standard, even when the risk is low, every house would cost a million dollars. Obviously, the local building code rules the day, but aside from that, some common sense needs to be applied.
Our radon filter is SO LOUD and it's only 6 months old
Since it is a new build why wouldn't you put the pipe in the stone and take it to the Perimeter of the house along with putting Perimeter pipe around the foundation like your drain, so you aren't sucking in gas from the surrounding land?
The drain tile is on the perimeter, but it has to come inside to get to the sump pump. You can't have the sump pump outside because it could freeze up in the winter since it has to have an access cover.
@@ColeSpolaricIf you have pipe around the house in the ground it will fill up with water and not evacuate the gas.
Im a licensed radion specialist. The EPA guidance for radon is a measurement of 4 piCU/L; any higher and it requires mitigation. Every real estate transaction should include a radon test. A short 6 min sampling is not very accurate. I run a minimum 48 hour continuous radon monitor. Weather impacts radon levels. New construction passive systems are worthless. Radon is 7.5 times heavier that air. Radon will not rise in a passive system. The problem is that realtors convice buyers to waive home inspections and radon testing so they reduce impediments to their commission.
The 6 minute test mentioned was with the professional-level monitoring device shown and costing several thousand dollars. The mitigation company brought that to test each location and the results were almost identical to the AirThings ViewPlus devices that had been in place for more than a week.
Also your machine has to be calibrated and you need to be setting it up correctly
I'm glad these build show videos are being published to youtube more consistently because the build show website sucks! I don't know who designed the layout on that site, but they did a sh*tty job.
I will let them know
@@stevenbaczekarchitect9431 Thanks!
@@dlg5485 Our goal is to provide the very best information we can
Homeowners take all the fun out of building!
Here it is in the state building code
Has anyone tied the radon pipe into a HRV?
Works great when tied into supply
@@IYG-x7c 😬😜😂
PVC PIPE DOES NOT TOLERAT UV LIGHT! not painted or wrapped in something to protect UV pipe from UV light.
radon in your home in deadly amounts is just a myth
Well it is in the building code in some states....
So you would sleep/live in the home that measured 300?
It's actually not, do some research.
@@kylekelley213 Thank you sir - since 2015 IRC Appendix F Massachusetts State Building Code "REQUIRES" a radon mitigation system
@@stevenbaczekarchitect9431
I was trying to give you a compliment and reiterate what you said was correct. As I have been studying to get my radon mitigation license for Illinois, I know all about radon in the effects of it from all the studying and research I have done. I was telling someone in the comments to do there own research because they said radon was a myth. Why you so upset that I told someone it's not a myth?
Radon is a lie.
I would have to disagree, based on the science. Is there research that you can point to that debunks all of the science that has been out for many years. The research I have seen supports the dangers of radon and that it is the leading cause of lung cancer deaths among non-smokers? If you have any research data that you believe debunks this, please help everyone by providing that material. Would you want your family, including young children, to live in a house that had elevated radon levels without addressing the issue? It is pretty straightforward to mitigate the radon in an existing house and even easier to do so with a home being built.
@@scottrodman4017 - “Science” - ok sure.
Wtf is radon
Lots of credible information online. I'd suggest you Google it.
Basically an odorless gas that will give you cancer, but yeah google it
A radioactive gas that naturally occurs in the soil.
It's a radioactive gas and no2 cause of lung cancer after smoking
Radon in buildings is more a myth than reality.
"Rodon" may be, but radon is definitely real.
So would you live / sleep in a house measuring 300?
@@scottburton414
Thank you.
@@stevenbaczekarchitect9431
300 Bq/m3?
Most of the time real cause of cancer is granite in concrete.
Its like Jan 6: one more thing to scare home owners into buying multiple $250 gadgets. Level 16 radon. Give me a break. Unless you actually live in the basement, who cares.
If your HVAC system is in the basement, it’s sucking radon up from there & dispersing it through the living areas of your home whenever it’s running.
It’s only science, smoking doesn’t really kill right?
I've heard aerocrete can do that for ya?...