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Radon gas mitigation in our home.

John Conroy

John Conroy

member
Premium Member
We have lived in the same house since 1992, raised our kids here and plan to stay until they carry us out. Recently a neighbor (lifetime non-smoker) was diagnosed with lung cancer and biopsy results showed the kind of lung cell damage that is caused by Radon gas. I had heard of Radon before but I never paid much attention to the topic and there doesn't seem to be much common discussion of the issue. Radon is the leading cause of lung cancer in non-smokers! After our neighbor was diagnosed, they did a Radon level test in the house and found it to be over 5 times the recommended maximum level. Info regarding units of measure and such here:

Guide for Radon Measurements in Residential Dwellings (Homes) - Canada.ca

Guide for Radon Measurements in Residential Dwellings (Homes)
www.canada.ca www.canada.ca

We have since done one of the mail in Radon tests in out home and the results showed levels at 275 Bq/m3 over a 3 month average from September to December. Since the recommended max level is 200 I wanted to do something about this. We had a local Radon mitigation company come out and do an evaluation and give us a quote for about $3000 to install a mitigation system. I have done quite a bit research on Radon mitigation since and decided to attempt to install my own system. It's pretty simple really. The gas enters the dwelling from the soil under the building and the object is to install a fan and vent system to direct the gas from under the slab to outside. We were fortunate that our house has a sump pump pit hear the center of our basement slab that was installed by building code when the house was built in 1985. There is a 6" layer of crushed gravel under the slab that allows air to circulate. Being the skeptic that I am I wanted to double check the Radon level but not wait another 3 months so I purchased a digital Radon detector made by Air Things. It can provide a gas level after about 6 hours and will provide short term ( 1 day) and long term ( up to 7 days) averages as well as history up to 1 year.

AIRTHINGS Corentium Home , Radon Gas Detector, Canadian Version in Bq/m : Amazon.ca: Tools & Home Improvement

AIRTHINGS Corentium Home , Radon Gas Detector, Canadian Version in Bq/m : Amazon.ca: Tools & Home Improvement
www.amazon.ca

I measure the levels in 3 different areas of the house over a period of 3 weeks and found that they were actually worse than what the mail in report showed. That makes sense to me because during September and October there were quite a few days where we had windows open in the house allowing ventilation of the gas. No windows open here in January.



My plan was to buy a fan kit of sufficient size based on the size of the slab (1575 sq feet) and type of soil under it. I chose to buy a fan from Amazon made by a company called RadonAway and using their sizing information picked the RP145 model which is one of the most common ones. ($230)

RadonAway 23030-1 RP145 Radon Mitigation Fan, 4-Inch : Amazon.ca: Tools & Home Improvement

RadonAway 23030-1 RP145 Radon Mitigation Fan, 4-Inch : Amazon.ca: Tools & Home Improvement
www.amazon.ca

To learn about the proper installation type I used a guide published by the Standards Council of Canada to make sure my installation is up to code. You can download it here.

Radon mitigation options for existing low-rise residential buildings .: P29-149-012-2017E-PDF - Government of Canada Publications - Canada.ca

Publication information / bibliographic Record.
publications.gc.ca publications.gc.ca

Since we live in a cold climate area I chose to mount the fan indoors and to use a vent system that exits the side of the house. Outdoor fans and through the roof style vents are commonly used where the climate is milder. I chose to use 4" schedule 40 ABS pipe and fitting as it is much cheaper and easier to get than 4" PVC. I found that Lowes price on the pipe was about 30% lower than Home Depot for some reason. I needed three 12' pieces of 4" pipe, as well as a bunch of fittings that totaled just over $300.

I used the existing plywood cover from the 2' X 2' sump pit and added another layer of G1S plywood on top of it to add stiffness and sealed it to the opening with foam tape. Our house is on high ground so there has never been a pump or any water in the pit but I want to be able to remove the cover if need in the future so it is fastened and sealed down with 12 screws. Since the OD of the 4" pipe is 4.5" I used a 4.75" hole saw to make the opening in the plywood cover. I machined a flange for the pipe to fit through from a 2" thick piece of 6.75" round steel and bolted that to the cover and sealed it with silicone.













The finished installation.



Radon level after 6 hours of operation.



Radon level after 48 hours of operation.



My only regret is I didn't do this years ago. Total for materials and the detector about $750.
 
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This is great and gives me lots of ideas, thank you. Our home is in an area which is notoriously bad geographically for radon gas. I did do a mail-in test a few years ago from opposite ends of our basement, and one room was below the 200 threshold, and one was slightly above, so I chose not to do anything at the time. The consultant I was speaking with had offered to sell me a real-time detector, but it was quite a bit more than the Airthings linked above. I'm going to order one of those right away.
 
John Conroy said:
We have lived in the same house since 1992, raised our kids here and plan to stay until they carry us out. Recently a neighbor (lifetime non-smoker) was diagnosed with lung cancer and biopsy results showed the kind of lung cell damage that is caused by Radon gas. I had heard of Radon before but I never paid much attention to the topic and there doesn't seem to be much common discussion of the issue. Radon is the leading cause of lung cancer in non-smokers! After our neighbor was diagnosed, they did a Radon level test in the house and found it to be over 5 times the recommended maximum level. Info regarding units of measure and such here:
Click to expand...
John thank you for raising radon awareness with your post. It may be off topic but it should be a discussion we have everywhere in Canada.

My career was spend predominantly in working in building science, mechanical design, occupational hygiene, and heavily involved identifying and mitigating indoor environmental risks. At one time I was the Director of Programs and Technical Services for a Natural resources' Canada Service Organization that was owned by the Ontario homebuilders' Association. Each province at the time had one organization that worked with very large "production homebuilders to get them to voluntarily improve the durability, energy efficiency, and health and safety of the housing that they developed.

As an organization we were a also major stakeholder in Natural Resources Canada's Energy Efficiency in Housing programs. We provided subject matter expertise in building science, energy efficiency, best practices in construction input to the feds, while also acting as a liaison between the feds and the provinces homebuilding community. We were also prime stakeholders in the provincial utility companies' demand management programs and in provincial building code consultations.

Our organization basically helped to create the R2000 Homes Standard, the Energuide For Houses Ratings system, The EnergyStar for New Homes standard, and a voluntary program called "Radon Ready"

The goal of all these programs is to affect voluntary change by demonstrating the benefits of the program to builders and potential homebuyers. With a radon ready home houses constructed in that program would seal the edges of the foundation slab, and install a passive pipe that penetrated vertically up and thru the roof with as little deviation from vertical as possible. Those builders who made this small investment received training, marketing assistance and were supposed to benefit from a national advertising campaign. The ultimate goal was to attempt to have every home outfitted with a system that was inexpensive yet very efficient that could be upgraded with the addition of a fan for which wiring had also been preinstalled if testing revealed passive mitigation was insufficient.

One a side note, that same department actually helped to create heat recovery ventilators in response to high radon levels in Saskatchewan homes in the 1980s. The province still has one of the highest levels of lung cancer in the nation. Despite having a massive uptake of heat recovery ventilators, they are not reaching everyone.

The radon ready program failed to sway builders, or win over consumers, just like EnergyStar, and Energuide for New Homes because the feds reneged on their commitment to actually promote theses programs to new homebuyers. I wont say which party did the most damage to the feds credibility, but it was a western one.

In the end, we affected change like we eventually always have to do. We mandated changes thru the building codes and local construction ordinances. Radon mitigation is ultimately being codified slowly but surely. But how many people will have died in the interim? antimaskers will say so what.
 
A few years back one of the engineers did his 'safety moment' on radon. There was a period after that where people were comparing notes about variation among testers & test duration. It's naturally occurring but I recall there were factors around why the levels varied & accumulate (seasonally or ventilation related?). They even had one of the companies come in on a lunch hour & give a talk but I missed it.

And then there is 'unnaturally' occurring radiation. Fortunately, our border has completely insulated us from any airborne migration originating from the south - clearly evidenced by how the red shade just ends as you approach the line of frozen hinterland of Kanukistan.
 

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PeterT said:
A few years back one of the engineers did his 'safety moment' on radon. There was a period after that where people were comparing notes about variation among testers & test duration. It's naturally occurring but I recall there were factors around why the levels varied & accumulate (seasonally or ventilation related?). They even had one of the companies come in on a lunch hour & give a talk but I missed it.

And then there is 'unnaturally' occurring radiation. Fortunately, our border has completely insulated us from any airborne migration originating from the south - clearly evidenced by how the red shade just ends as you approach the line of frozen hinterland of Kanukistan.
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Sadly, unlike the USA, Canadian govts always claim they could never afford to test nationally for radon and produce maps like the USA has. Radon is so widely varied across Canada. In some regions of the province the levels are huge, yet just a few kilometers away the levels are low.

Radon levels vary by season due to what is called stack effect. when there is a major difference between the indoor and outdoor temperatures the difference in temps causes pressure differentials that drive air leakages thru the leaky building envelope. In the shoulder months of the spring and fall, we don't operate hvac equipment as often, the temperature differential is low therefore there are no forces to drive ventilation. Pollutants including radon builds up, often to dangerous levels.

New homes are being made even tighter so they must have controlled mechanical ventilation and radon mitigation built in.

When I lived in SK our home had a central areas of full basement surrounded by crawlspaces. The crawl spaces had bare dirt foundation floor, held back by cinderblock kneewalls. This design is rather typical of many homes built in the early 1900s in the province. Not even the leaky old homes provided enough ventilation resulting in high rates on lung cancer.

I could expound on this subject for hours, and I used to be paid to.
 
And here I thought asbestos clad houses and lead based paint on cribs were the only skeletons in my closet. Radon eh?
 
YYCHM said:
And here I thought asbestos clad houses and lead based paint on cribs were the only skeletons in my closet. Radon eh?
Click to expand...
Oh Craig, dont forget the Federal govts' early insulation programs stemming from the 1970s oil crisis. The feds paid to have vermiculite insulation dumped in heaps in attics, and poured into wall cavities. Later testing revealed that the major mine supplying the vermiculite was contaminated with asbestos veins all thru the vermiculite.

This was only discovered in the late 1990s or early 2000s IIRC. The feds then had to conduct major testing depressurizing homes with blower doors to see if any asbestos was able to enter the living spaces. Most of this testing happened in Canada's lousy Canadian Forces Housing stocks because these facilities were all insulated during the 1970s insulation program.

During these inspections we discovered a myriad of issues and abuses. In many cases unscrupulous contractors merely carried up bags of insulation and laid them around the attic space leaving gaping holes in the coverage. They took the money and ran because at the time the feds had zero oversight or inspection protocols.
 
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Johnwa said:
We participated in a UofC radon study. We had two different tests, one in the basement and one on the main floor. Our values were well below the recommended limit.
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that's good. calgary housing stocks are better build in the foundation and substantially newer on average.

SK has more residual uranium deposits in the soil that came from the athabasca basin but alberta has elevated levels too.
 
Okay, last comment. One that puts the radon risk into glaring perspective.

A Cross-Canada survey conducted by Health Canada between 2009 and 2013 of radon concentrations in Canadian homes. The survey found that 25.2% of homes had radon concentrations equal to or greater than the recommended WHO remediation action level of 100 Bq/m³ and 8.2% had radon concentrations equal to or greater than the recommended Health Canada remediation action level of 200 Bq/m³.

There is a 25% chance your house is trying to kill you by a method other than slipping in the tub or falling down the stairs. I know several people who died of lung cancer. It is horrible way to die.

What does this mean for you?

A subsequent 2014 study concluded that more than 2 times as many lung cancer deaths could be prevented each year in Ontario alone if all homes with radon levels above 100 Bq/m³ were remediated instead of only remediating homes with concentrations above 200 Bq/m³.

You should have your home tested. The timing of the testing should be in the shoulder months of the spring and fall when natural ventilation levels are at their lowest. If your home exceeds 100 Bq/m³ you should look into mitigation with either a heat recovery ventilator, a sub-slab ventilation system, or perhaps both depending on your test levels.

Oh and that 25% of homes is an average. Some areas are very low, and some very high. In Ontario three regions averaged over 40% of the homes testing above 100 Bq/m³.

Windsor-Essex County (44.1%); Leeds, Grenville and Lanark District (41.7%); and Chatham-Kent (39.8%).
 
Janger said:
Radon maps of canada, lots of them,

radon map canada

And this one of Calgary:

Click to expand...

These maps do not typically represent the levels of radon in homes but rather the presence of decaying uranium in the soils that releases isotopes such as radon. Housing typology and construction type and quality also play a huge role in whether a home has radon infiltration and accummulation.

So please do not look at a map alone and think "great, the levels in my area are low therefore my risks are low." Do look at a map that shows higher levels of uranium and it's isotopes in the soil and think "damn I may be at risk, I need a radon test"

All of these maps have been produced within the last 15 years or so based on rushed testing as well. I have little faith in their reliability compared to simple radon testing
 
TorontoBuilder said:
These maps do not typically represent the levels of radon in homes but rather the presence of decaying uranium in the soils that releases isotopes such as radon. Housing typology and construction type and quality also play a huge role in whether a home has radon infiltration and accummulation.

So please do not look at a map alone and think "great, the levels in my area are low therefore my risks are low." Do look at a map that shows higher levels of uranium and it's isotopes in the soil and think "damn I may be at risk, I need a radon test"

All of these maps have been produced within the last 15 years or so based on rushed testing as well. I have little faith in their reliability compared to simple radon testing
Click to expand...
Good clarification John.
 
My house has one of those sump pumps in the buckets and I have heard it run so IF I have a problem then I can't install the pipe there like John C. did. How far away from the sump pump should the venting hole be drilled? In my furnace room you could put it about 6 feet away. If it is too close to the sump I would think the fan would just draw all the air from the holes in the sump pump bucket? Least path of resistance? That would not really work to pull any radon out?
 
Janger said:
My house has one of those sump pumps in the buckets and I have heard it run so IF I have a problem then I can't install the pipe there like John C. did. How far away from the sump pump should the venting hole be drilled? In my furnace room you could put it about 6 feet away. If it is too close to the sump I would think the fan would just draw all the air from the holes in the sump pump bucket? Least path of resistance? That would not really work to pull any radon out?
Click to expand...

Foundation floor slabs are laid on a gravel drainage bed and capillary break... The standards for gravel used in drainage fields is written to assure that the aggregate size is such that when compacted the openings between the gravel will be large enough to provide a capillary break. This prevents water from rising to touch the floor slab via capillary action.

This provides another benefit. The entire sub-slab area is one connected air space. Think of it as a very very short room, albeit a crowded and stuffy one.

Many such sub slab areas also have a sump pit, It will not interfere with radon mitigation piping. The water entering the sump pit travels along the lowest level of the gravel field. The sump pit is also a radon accumulation point and potential point to allow both radon and water vapour access into the home.

You could very well use the sump pit as a site to add radon mitigation piping however, it is not best practice because sump pits are almost never sited so that you can run a vertical vent pipe thru the home.

As well, radon mitigation pipes need a little help, since some are passive and work entirely due to what is known as stack effect. Due to temperature differentials between the outside and inside of the home and between the basement and upper floors there is almost always a pressure driving air movement upwards in a home. In a radon mitigation system that flow is from the sub-slab area and out thru the room.

Gravel impedes airflow though, so the best system is to install a tee just below the slab, and perforated pipe in both directions to increase the radon collection area and make air movement to the exterior of the home easier.

Most of my work was with new homebuilders, so we could install pipe during construction prior to pouring the slab. We usually recommended that one end of the pipe penetrate the side of the sump pit, and the other end extend as far as possible in the other direction. The tee location was carefully planned from the very start of the design process so that it would be vertical without any bends.

in retrofit situations you want to be able to break a narrow trench through the slab as long as you can. In many homes that means just a few feet... but in some it could be 20 feet. It is an easy task to break the slab with a 5 pound sledge hammer, and then dig out gravel to make room for perforated pipe. You want to be able to cover the pipe with at least 2 inches of concrete.

you need to ensure that your patch will provide good adhesion to the old concrete. Little cracks can allow radon to penetrate into the basement

DS112_RadonFan-1_Slab%20BSC.jpg
 
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