Radon gas mitigation in our home.

[deleted_user]

You can buy a ready made sump pit cover or make one that allows both the pump and the radon suction pipe to be in the same pit. This one wouldn't fit my sump pit as mine is square but it will illustrate what I mean.

The Original Radon/Sump Dome (Model: SMR16101-CV) : Amazon.ca: Tools & Home Improvement

The Original Radon/Sump Dome (Model: SMR16101-CV) : Amazon.ca: Tools & Home Improvement

www.amazon.ca

True. Most builders use a simple plywood cut out. It is stiff and seals well. However, the sum pit alone is not a sufficient radon catchment area... it is best to also extend perforated pipe into the gravel bed to provide as much coverage as is reasonable in the individual case.

 

[Susquatch]

Windsor-Essex County (44.1%); Leeds, Grenville and Lanark District (41.7%); and Chatham-Kent (39.8%).

Oh oh.......

Nothing in my first two homes in Windsor-Essex. Ventilator in my third.

Ventilator in my 4th here in Chatham Kent.

Prolly too late to change much at my age but I'll take a look at my ventilator spring & fall schedule anyway.

 

[John Conroy]

True. Most builders use a simple plywood cut out. It is stiff and seals well. However, the sum pit alone is not a sufficient radon catchment area... it is best to also extend perforated pipe into the gravel bed to provide as much coverage as is reasonable in the individual case.

From the research I've done it appears that most of the mitigation retrofits in older homes, even the ones done by professional mitigation companies, only involve piercing a hole in the basement slab and using a chipping bar or other narrow digging tool and a shop vacuum to remove about 10 gallons of material to form a small pit under the slab. At that point they just place a short length of pipe below the slab, seal it in and connect the fan and related vent pipe. The document I read from National Standards Canada (link in my original post) says venting out the side of the house is recommended in cold climate areas to prevent heavy snow accumulation and ice from blocking the vent. They provide a list of clearance specifications regarding the distance required between the radon vent outlet and things like opening windows, furnace air inlets etc. My sump pit is a cube shape 2 feet in each dimension so about 60 US gallons in volume and I just extended my pipe 6 inches below the slab and sealed it up. I have since tested radon levels in all areas of the basement and the rest of the house and show levels less than 5 bq/cubic meter.

My son works in the HVAC industry and tells me that most new home builders in the Edmonton area don't even install radon mitigation rough in piping below the slab in new homes. His company also has a branch in Kelowna and all the new homes they install hvac into there, also get a radon mitigation rough-in so there is passive mitigation piping done through the roof. The buyer can then do radon testing after moving in and if needed they can install a fan and upgrade the system to an active one.

It appears that it's up to each individual builder to decide whether a radon mitigation rough in is done when new homes are built. I find it pretty disturbing that radon mitigation rough-ins are not done on all new homes. If the material below the slab in not porous to allow airflow it could be very difficult to achieve an efficient mitigation with a retrofit.

 

[deleted_user]

From the research I've done it appears that most of the mitigation retrofits in older homes, even the ones done by professional mitigation companies, only involve piercing a hole in the basement slab and using a chipping bar or other narrow digging tool and a shop vacuum to remove about 10 gallons of material to form a small pit under the slab. At that point they just place a short length of pipe below the slab, seal it in and connect the fan and related vent pipe. The document I read from National Standards Canada (link in my original post) says venting out the side of the house is recommended in cold climate areas to prevent heavy snow accumulation and ice from blocking the vent. They provide a list of clearance specifications regarding the distance required between the radon vent outlet and things like opening windows, furnace air inlets etc. My sump pit is a cube shape 2 feet in each dimension so about 60 US gallons in volume and I just extended my pipe 6 inches below the slab and sealed it up. I have since tested radon levels in all areas of the basement and the rest of the house and show levels less than 5 bq/cubic meter.

My son works in the HVAC industry and tells me that most new home builders in the Edmonton area don't even install radon mitigation rough in piping below the slab in new homes. His company also has a branch in Kelowna and all the new homes they install hvac into there, also get a radon mitigation rough-in so there is passive mitigation piping done through the roof. The buyer can then do radon testing after moving in and if needed they can install a fan and upgrade the system to an active one.

I find it pretty disturbing that radon mitigation rough-ins are not done on all new homes. If the material below the slab in not porous to allow airflow it could be very difficult to achieve an efficient mitigation.

Hi John,

I was one of the technical experts and stakeholders who contributed to radon mitigation standards for Natural Resources Canada. There are many competing interests involved in such a process. Often builder's representatives lobby to do the least possible, and due to the lack of their own unbiased representation means that renovation contractors lack a voice in such efforts. The opposite is true as well, renovation contractors organizations dont get to hear the debate and the input into the standards and how much the best practice recommendations get watered down.

It is true, in most cases radon mitigation retrofits fail to use the best practice methods, because just like builders homeowners want to pay the least possible amount rather than attain the best air quality. I only hope that every homeowner has a contract that includes a payment schedule over 6 months and that requires that the system pass two tests prior to the release of two payments held in escrow.

And it is also true as I mentioned, the radon ready program failed to gain any traction. Builder's claimed that they'd never make any profit if they had to install radon ready passive systems in homes. Note builders claimed the same thing during code consultations that were considering making HRVs mandatory in all new homes back when the average new home price was about $225,000. The average home price is now

I am glad that you too find it disturbing. Well I actually find it criminally negligent... but production builders have one of the most influential lobbies in Canada. We need people like you to write to our provincial leaders to lobby for changes to codes to mandate at least the minimum radon mitigation of a ready ready home.

Oh and I forgot to add... the feds under pressure from lobbyists and conflicting advice, or the lack of a standard condition always try to simplify and fall back to the lowest common denominator. So in the case of basements that base condition is that every basement at least should have an open floor area of 9 square feet near an exterior fall in which a dry sump pit can be placed to accumulate and vent any soil gasses before they can infiltrate the home.

The thinking behind that decision was that if at least a section of the foundation area could be depressurized sufficiently that the balance of the areas that continued to permit radon infiltration would be low enough, that in combination with the higher level of natural ventilation in leaky older holes would result in radon rates lower than 100 bq/m3

 

[StevSmar]

Our house in Winnipeg had radon levels which were about 350, luckily not super high but high enough that I decided to install a radon fan.

One great side effect is that it improved the concrete efflorescence issue we also have, by the ventilation helping to dry out underneath the slab.

It wasn’t a hard install and I think I spent about $500 in total about seven years ago. I vented out the side of the house since Radon is heavier than air and there weren’t living space windows nearby. Peak Radon levels occur in the late winter (if I recall correctly), so the windows are still closed during the Radon “peak” anyway.

Now our radon levels in the basement are about the same as “ambient” radon levels outside (I doubt my meter reads that accurately at this level so “about the same” could mean twice, but our interior readings are about 25% of what they were before the install (if my meter is linear…))

 

[DPittman]

So I'm not fully researched on this subject yey, so I'm going to ask a couple of questions that might be basic.

I have an older home (66 years) and have put in weeping tile around the footing and made a sump pump hole in the basement. Is the drainage tile and open sump hole (that's dry most of the time) likey spots for radon entry?

 

[deleted_user]

So I'm not fully researched on this subject yey, so I'm going to ask a couple of questions that might be basic.

I have an older home (66 years) and have put in weeping tile around the footing and made a sump pump hole in the basement. Is the drainage tile and open sump hole (that's dry most of the time) likey spots for radon entry?

Yes.

Radon can infiltrate into the home via a simple crack in the concrete floor. An open sump pit is like an open garage door.

The are many reasons why we want to ensure that our foundations have zero penetration points. Radon is just one of them.

 

[StevSmar]

Is the drainage tile and open sump hole (that's dry most of the time) likey spots for radon entry?

For the floor drain in the laundry, I installed a “Dranger” cover that has a built in P-trap. It’s a pain to keep it filled with water but it provides a vapour seal (our weeping tiles drain into the floor drain)

I don’t know how you’d seal the other floor penetrations, I imagine it could be something similar?

 

[DPittman]

So it appears to me (if i understand correctly) radon reduction systems draw the air up from beneath the floor foundation and vent it out. Would pressurizing my sump hole and forcing air out through the drainage tile work. That's assuming cracks in floor or wall are not available/easier paths for the radon gas to re-enter?

 

[deleted_user]

So it appears to me (if i understand correctly) radon reduction systems draw the air up from beneath the floor foundation and vent it out. Would pressurizing my sump hole and forcing air out through the drainage tile work. That's assuming cracks in floor or wall are not available/easier paths for the radon gas to re-enter?

There is real danger of pressurizing the subslab area and causing more infiltration into the home via other pathways.

The best practice is always to seal sumps, and then vent them out by depressurizing the subslab and expelling the soil gasses to the exterior with an inline fan...

 

[deleted_user]

For the floor drain in the laundry, I installed a “Dranger” cover that has a built in P-trap. It’s a pain to keep it filled with water but it provides a vapour seal (our weeping tiles drain into the floor drain)

I don’t know how you’d seal the other floor penetrations, I imagine it could be something similar?

Older homes where the sanitary sewer and the stormwater sewers are combined are more difficult to seal. That you installed a p-trap is great. Best practice method. They make laundry taps with a small side tap that you can connect to tubing that will prime the p-trap evry time someone uses the faucet.

Other penetrations typically get caulked. Unless it is a exposed dirt crawlspace that is

 

[StevSmar]

The way radon primarily gets into a house, is that during the winter the ground freezes so the Radon gas needs to go somewhere, and the path of least resistance is through an area that’s not frozen, like a basement. (This is a simplified explanation)

(It’s hard not to get “carried away” with the risk that Radon presents, we’ve been accustomed to thinking of all radiation as being bad. My own personal unsubstantiated and uneducated opinion is that Lung Cancer rates in Winnipeg are not sky high, so perhaps Radon is not as great a direct risk as we might think? The reading I did suggested that smoking was a much higher risk factor. I’m neither a doctor nor scientist, so my opinion should be treated accordingly. Perhaps I’ve just become accustomed to Radon being present so it no longer concerns me, though it was comforting to find that after installing a fan, my basement radon levels were not much different from those outside)

 

[StevSmar]

…They make laundry taps with a small side tap that you can connect to tubing that will prime the p-trap evry time someone uses the faucet.

Wow, that’s great to know this!!! I’m always having to remember to check the floor drain and fill it probably once every two weeks.

 

[deleted_user]

The way radon primarily gets into a house, is that during the winter the ground freezes so the Radon gas needs to go somewhere, and the path of least resistance is through an area that’s not frozen, like a basement. (This is a simplified explanation)

(It’s hard not to get “carried away” with the risk that Radon presents, we’ve been accustomed to thinking of all radiation as being bad. My own personal unsubstantiated and uneducated opinion is that Lung Cancer rates in Winnipeg are not sky high, so perhaps Radon is not as great a direct risk as we might think? The reading I did suggested that smoking was a much higher risk factor. I’m neither a doctor nor scientist, so my opinion should be treated accordingly. Perhaps I’ve just become accustomed to Radon being present so it no longer concerns me, though it was comforting to find that after installing a fan, my basement radon levels were not much different from those outside)

This is wrong. uranium particles in the decay year round, including when the surface grade is frozen to the frost line...

soil gasses enter homes year round. Radon is a year round risk, with the highest risks being in the shoulder months of spring and fall, when our furnaces or air conditioners have yet to come on for the season and our homes have the least stack effect and least ventilation. Ventilation and infiltration rates play a key role in risk right after uranium levels in soil.

25% of the homes in Canada are at risk, regionally up to 40% of homes. Winnipeg is bad. The Health Canada survey found that Manitoba has the second-highest percentage, at 23.7 per cent, of homes in the country with radon concentrations over 200 becquerels. But that number of homes would more than double if Canada adopted the World Health Organization's limit of 100 becquerels.

at 100 bq the lung cancer incidence is high, 2 times as many lung cancer deaths could be prevented each year alone if all homes with radon levels above 100 Bq/m³ were remediated instead of only remediating homes with concentrations above 200 Bq/m³.

So basically 50% of Manitoba homes need remediation, of screw the victims.

I rely on science and informed and education opinions myself

 

[StevSmar]

This is wrong. uranium particles in the decay year round, including when the surface grade is frozen to the frost line...

@TorontoBuilder
- Yes, it is true that the Radon decay process is not effected by whether the ground is frozen.
- It’s my belief too that Radon infiltration into a house is primarily from the stack effect (from temperature differential), however if the temperature differential was the only factor, then why do radon levels peak in the mid to late winter in Winnipeg and not have similar levels in December when it’s just as cold? (If I remember correctly December and January in Winnipeg had pretty similar heating degree days) The only explanation I can think of is that the ground is now deeply frozen so the easiest path for radon to escape is through a house via the basement. (Perhaps it’s related to packed snow levels, though packed snow seems to be quite porous to me?)
- I don’t dispute the high number of Canadian homes which have higher levels of Radon, but if Radon is such a risk, then why isn’t there a greatly increased number of Lung Cancer deaths in Winnipeg and the other areas of Canada which higher than average levels of Radon? The conclusion I came to is that Radon is a risk factor, and other factors such as smoking, appeared to be higher risk factors for Lung Cancer.
- I investigated Radon about 7 years ago and the links to Lung Cancer seemed rather tenuous, I acknowledge that my knowledge is getting rather dated.

For others reading this thread, the practical reason for wanting to know when the seasonal peak for Radon occurs in your area is only because this is when you should test.
(The actual mechanism for the peak is interesting to me, but it’s more academic than practical.)
(Health Canada does recommend you avoid areas when they have high Radon levels, but I don’t consider this practical, especially since the basement is where I have my workshop…)
Because I installed a Radon fan that shows I made the decision that Radon was a risk factor that I wanted to decrease, especially because it was a risk factor I could decrease. And since Radon reduction is a realatively simple thing to do, why wouldn’t you do it.

 

[deleted_user]

@TorontoBuilder
- Yes, it is true that the Radon decay process is not effected by whether the ground is frozen.
- It’s my belief too that Radon infiltration into a house is primarily from the stack effect (from temperature differential), however if the temperature differential was the only factor, then why do radon levels peak in the mid to late winter in Winnipeg and not have similar levels in December when it’s just as cold? (If I remember correctly December and January in Winnipeg had pretty similar heating degree days) The only explanation I can think of is that the ground is now deeply frozen so the easiest path for radon to escape is through a house via the basement. (Perhaps it’s related to packed snow levels, though packed snow seems to be quite porous to me?)
- I don’t dispute the high number of Canadian homes which have higher levels of Radon, but if Radon is such a risk, then why isn’t there a greatly increased number of Lung Cancer deaths in Winnipeg and the other areas of Canada which higher than average levels of Radon? The conclusion I came to is that Radon is a risk factor, and other factors such as smoking, appeared to be higher risk factors for Lung Cancer.
- I investigated Radon about 7 years ago and the links to Lung Cancer seemed rather tenuous, I acknowledge that my knowledge is getting rather dated.

For others reading this thread, the practical reason for wanting to know when the seasonal peak for Radon occurs in your area is only because this is when you should test.
(The actual mechanism for the peak is interesting to me, but it’s more academic than practical.)
(Health Canada does recommend you avoid areas when they have high Radon levels, but I don’t consider this practical, especially since the basement is where I have my workshop…)
Because I installed a Radon fan that shows I made the decision that Radon was a risk factor that I wanted to decrease, especially because it was a risk factor I could decrease. And since Radon reduction is a realatively simple thing to do, why wouldn’t you do it.

The fact is that peak radon levels are related primarily to the driving force of radon, air infiltration, and that is natural ventilation caused by stack effect. Of course there are many other contributing factors and some houses will test as outliers because they have other factors that weigh more heavily than natural ventilation.

As I mentioned earlier in this thread that IS the shoulder months of spring and fall.

My opinion is informed by decades of working in building science, having personally tested 100s of homes for air infiltration and supervised and reviewed infiltration testing of thousands of homes.

Additionally my firm conducted extensive surveys using tracer gas testing and blower doors to investigate if and how natural ventilation and blower door depressurization air tests may contribute to increased health risks of Canadian Homes. Some of the risks being examined in particular were soil gases including radon, insulation materials off-gassing, outdoor pollutants, and asbestos insulation and siding products.

What informs your opinion?

 

[Janger]

I appreciate the discussion.

 

[deleted_user]

I appreciate the discussion.

I do too, but I'm not afraid to be challenging when I am top subject matter expert in Canada on a subject and someone tries to keep pushing misinformation. They can feel free to do so but I want to hear credentials in such cases.

one further point, only soil gasses coming from directly below your home and the immediate vicinity infiltrate homes. The soil below your home never freezes... because foundations must either be below the frost line, or conform to frost protected requirements to prevent freezing.

 

[Janger]

no flames is all I ask.

 

[YYCHM]

Anyone in Calgary have a hand held Radon meter I can borrow for a couple of days?