• Last Updated:
  • Feb 24th, 2020 11:01 am
Tags:
[OP]
Deal Addict
User avatar
Jan 2, 2012
3636 posts
2587 upvotes
KINGSTON,ON

Radon Abatement.

I thought I'd post this in case anyone is curious. I realise there are other threads regarding radon, but wanted to start anew.

Our house is a 1993 build, two story detached, block foundation and finished basement.
Last year I bought an Airthings Corentium radon tester, because I was curious about radon. I monitored the main living area of our basement for several months to see what levels there were, and how much fluctuation there was seasonally.
The levels did fluctuate, and were close to but not above, the Canadian recommended level of 200 Bq/m³.

Out of curiosity, I placed the monitor in the cold cellar. The cellar has an exterior door leading into it from the main basement, and also contains a sump pit with a rudimentary plastic lid. After a couple days, I checked the reading and was shocked to find a level of 1100 Bq/m³. Yikes.
We keep the cat litter box in the cold cellar (for odour reasons), and I had installed a cat door a while ago. Since radon gas is heavier than air, my guess is that it was seeping into the main area through the cat door.
Initially I was going to just seal the sump pit and continue monitoring, but with readings that high in one section only, I figured I should just go directly to mitigation since there was most likely seepage elsewhere.

After reading that attempting to seal the entire foundation is basically a fool's errand, I ordered a radon exhaust fan and set about with creating sub-slab depressurization.
Fortunately my furnace room is directly beside the cold cellar, which allowed me to cut a hole in the foundation wall and the floor slab on each side, join the two, and vent both the main slab and the cold cellar slab. (The footings would have caused a barrier since the gravel under the slab would have been separate.)
I routed the exhaust pipe out through an existing air vent in the cold cellar wall.

One of the issues I ran into was capping the sump pit. The pit tank had a diameter of 20 inches. A company called Radon Detect sells a 24 inch radon sump cover that would fit, but it's $179. I couldn't justify paying that much for a chunk of plastic. I was going to just cover the sump with some 6 mil poly and tape, but that was a bit too ghetto for me. A chunk of Lexan would have worked, but it's pretty pricey as well, and while it's strong stuff, I was worried that it may get stepped on.

I went to Lowes, and wandered from department to department looking for something suitable. Finally, I found just the thing. A Bigfoot deck/pier form, 24 inches in diameter. The top had steps that could be cut off to accommodate different sizes of sonotubes, which was perfect. I did have a small piece of clear acrylic hanging around that i could cut to size as the "lid", and would allow me to see into the pit to inspect the sump pump. The "step" that I picked was large enough to allow the sump pump to be removed without having to pull the Bigfoot away from the floor.

This is what the final product looks like.
Sump Lid

Here's the fan
Fan in place

72 hours in, the radon levels in the main basement area have dropped to 2 Bq/m³. I'd say this battle has been won.
18 replies
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
Thanks for the post.
What's that bypass tube you have there? Is that too drain condensation without it getting into the fan?
Where did you get the fan and for how much?
How did you cut the hole in the slab?
Thanks
[OP]
Deal Addict
User avatar
Jan 2, 2012
3636 posts
2587 upvotes
KINGSTON,ON
engineered wrote: Thanks for the post.
What's that bypass tube you have there? Is that too drain condensation without it getting into the fan?
Where did you get the fan and for how much?
How did you cut the hole in the slab?
Thanks
Yes, the clear tube is a condensation bypass for the fan. There's quite a significant amount of moisture being drawn from under the slab. I also had to go "up and out" to the exterior, and when it's -16C outside, there will be frost build up then lots of water when it warms up.
As a side note, some jurisdictions in the USA require the fans to be located outside, (presumably to avoid radon leakage in the event of some kind of failure,) and the pipe to be terminated above the roof line. I think this is crazy in cold climates. It was -15C over night, and the wall where my pipe exits has a significant build up of hoar frost. I can only imagine the amount of frost there would be in 30' of exposed pipe.

I purchased the Radon Away fan from Amazon. This is the one I bought for $200. I forgot to add the manometer when I place the fan order, so got burned for free shipping. Doh.

To cut the holes in the slab and block wall, I rented a coring bit and Hilti drill from Home Disappointment. I don't know what I was thinking at the time, (clearly I wasn't), because a 4" coring bit is exactly 4", and the outside diameter of 4" PVC pipe is larger than 4". I know this, but I was fixated on a smooth, clean hole. I ended up enlarging the holes with my Bosch SDS rotary hammer drill, which I should have just used in the first place. I could have drilled a circle of holes with a 1/4" bit then used the chisel bit to knock out the concrete. I used backer rod and Sikaflex construction adhesive as a sealant. Some people recommend hydraulic cement to seal the openings, but I like the Sikaflex because, well, it's flexible.
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
MrFrugal1 wrote: Yes, the clear tube is a condensation bypass for the fan. There's quite a significant amount of moisture being drawn from under the slab. I also had to go "up and out" to the exterior, and when it's -16C outside, there will be frost build up then lots of water when it warms up.
As a side note, some jurisdictions in the USA require the fans to be located outside, (presumably to avoid radon leakage in the event of some kind of failure,) and the pipe to be terminated above the roof line. I think this is crazy in cold climates. It was -15C over night, and the wall where my pipe exits has a significant build up of hoar frost. I can only imagine the amount of frost there would be in 30' of exposed pipe.

I purchased the Radon Away fan from Amazon. This is the one I bought for $200. I forgot to add the manometer when I place the fan order, so got burned for free shipping. Doh.

To cut the holes in the slab and block wall, I rented a coring bit and Hilti drill from Home Disappointment. I don't know what I was thinking at the time, (clearly I wasn't), because a 4" coring bit is exactly 4", and the outside diameter of 4" PVC pipe is larger than 4". I know this, but I was fixated on a smooth, clean hole. I ended up enlarging the holes with my Bosch SDS rotary hammer drill, which I should have just used in the first place. I could have drilled a circle of holes with a 1/4" bit then used the chisel bit to knock out the concrete. I used backer rod and Sikaflex construction adhesive as a sealant. Some people recommend hydraulic cement to seal the openings, but I like the Sikaflex because, well, it's flexible.
My levels in the basement hover around 50-120 bq/m3, so I've been looking into doing this as well. Was planning to do the circle of holes. I also have a split level basement, so I'm wondering if I should do 1 fan on each level or just one on the lower one. I guess I can start with one and see how it goes.
I was also thinking of venting just to the side of the house, where there are no windows. Otherwise I've seen people reuse the waste water vent stack or a now unused furnace flume.

I agree that running the fan outside can cause issues in our climate and have seen many inside. Just need to be extra careful that the joints are sealed very well. Did you just use PVC glue or did you also add an extra bead of sikaflex around each joint?

How's the noise level of the fan?
[OP]
Deal Addict
User avatar
Jan 2, 2012
3636 posts
2587 upvotes
KINGSTON,ON
engineered wrote: My levels in the basement hover around 50-120 bq/m3, so I've been looking into doing this as well. Was planning to do the circle of holes. I also have a split level basement, so I'm wondering if I should do 1 fan on each level or just one on the lower one. I guess I can start with one and see how it goes.
I was also thinking of venting just to the side of the house, where there are no windows. Otherwise I've seen people reuse the waste water vent stack or a now unused furnace flume.

I agree that running the fan outside can cause issues in our climate and have seen many inside. Just need to be extra careful that the joints are sealed very well. Did you just use PVC glue or did you also add an extra bead of sikaflex around each joint?

How's the noise level of the fan?
Your split-level basement is obviously going to have two separate slabs. If possible, I would try and link the two (or do one slab and plan to connect the other) if your levels don't drop enough.
I seem to recall reading somewhere that tying it to the plumbing stack is it against Code. I would run it separately through the wall as you proposed.
And unless you were going to run a pipe directly to the top of the chimney I would not do that, because you have no idea whether the gases are then spilling back down and back into the room. Plus you have no idea what condition the chimney is in. You could end up pumping radon into another living area.

I primed and glued all the joints, but did not use any other sealant. The pipe liquid tight when glued, so nothing else needs to be done.

The fan is quiter than a cheap builder's grade bathroom fan, but it's certainly not as quite as a $200 Panasonic bathroom fan. You would want to put it in a utility room with a door, for sure.
Last edited by MrFrugal1 on Dec 20th, 2019 4:31 pm, edited 1 time in total.
Deal Guru
User avatar
Oct 6, 2010
14433 posts
8821 upvotes
Toronto
Nice.

I'm almost wondering if I can borrow said tester from someone but I really don't want to be doing any more work around just yet.
DYI difficulty scale:
0-joke
10-no joke

¯\_(ツ)_/¯
Newbie
User avatar
Oct 9, 2018
70 posts
17 upvotes
koffey wrote: Nice.

I'm almost wondering if I can borrow said tester from someone but I really don't want to be doing any more work around just yet.
I would also love to borrow a Radon tester from someone in the Toronto area.
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
koffey wrote: Nice.

I'm almost wondering if I can borrow said tester from someone but I really don't want to be doing any more work around just yet.
dflamez wrote: I would also love to borrow a Radon tester from someone in the Toronto area.
While you can some results after 48 hours you need 6-9 months to get a good average.
There are 1 time testers you can get for $50, while the digital versions are about $200.
[OP]
Deal Addict
User avatar
Jan 2, 2012
3636 posts
2587 upvotes
KINGSTON,ON
engineered wrote: While you can some results after 48 hours you need 6-9 months to get a good average.
There are 1 time testers you can get for $50, while the digital versions are about $200.
The $50 testers are "okay" if you want to find out if you have radon, but I believe that price doesn't include the lab test. If you want to do any kind of diagnostics as I did, it starts getting pricey and you may as well just buy a digital meter.

Check with your local health department to see if they have either a digital meter to lend out or the single use testers for a discount. Public Health here in Kingston was giving them out for free at one point, I believe.
[OP]
Deal Addict
User avatar
Jan 2, 2012
3636 posts
2587 upvotes
KINGSTON,ON
Just a follow up.
I used my meter to test my next door neighbours place to see what levels they had in their basement. The house was constructed a few years after mine, is a bungalow not a two story like mine, but it has a block foundation and has an open sump pit. After a week of testing, the reading was averaging 230 bq/m3, or 30 bq/m3 over Health Canada's guideline.
I've since lent the meter to another neighbour two doors away, also in a bungalow and also with an open sump, to see what readings they get.

My levels have remained at the 3-5 bq/m3 level since my system installation.
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
MrFrugal1 wrote: Just a follow up.
I used my meter to test my next door neighbours place to see what levels they had in their basement. The house was constructed a few years after mine, is a bungalow not a two story like mine, but it has a block foundation and has an open sump pit. After a week of testing, the reading was averaging 230 bq/m3, or 30 bq/m3 over Health Canada's guideline.
I've since lent the meter to another neighbour two doors away, also in a bungalow and also with an open sump, to see what readings they get.

My levels have remained at the 3-5 bq/m3 level since my system installation.
What's even more worrying is that the limit in the USA is 150bq/m3 and the WHO's is 100bq/m3.
[OP]
Deal Addict
User avatar
Jan 2, 2012
3636 posts
2587 upvotes
KINGSTON,ON
engineered wrote: What's even more worrying is that the limit in the USA is 150bq/m3 and the WHO's is 100bq/m3.
Even more worrying is that it was only 2007 that the Canadian guidelines were lowered from 800bq/m³ to 200bq/m³.
Thankfully new building codes require rough in for abatement if need be.
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
MrFrugal1 wrote: Even more worrying is that it was only 2007 that the Canadian guidelines were lowered from 800bq/m³ to 200bq/m³.
Thankfully new building codes require rough in for abatement if need be.
Yikes. Our consumer protection laws really do seem to lag behind the rest of the western world.

Rough in is better than nothing, but the codes should really require a poly barrier to prevent water and radon from entering basements.
Deal Addict
User avatar
Aug 12, 2007
4685 posts
805 upvotes
Waterloo
Has anyone have any experience with just putting in a HRV / ERV inlet in the basement area and the effect it had on Radon levels? ( Instead of a Radon fan in the floor which goes into the concrete )
----
Pay it forward.
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
Supahhh wrote: Has anyone have any experience with just putting in a HRV / ERV inlet in the basement area and the effect it had on Radon levels? ( Instead of a Radon fan in the floor which goes into the concrete )
I can tell you that running my 80% effect furnace which uses basement air, reduces the levels in my place by about 40% when it's running. My levels aren't too high so I'm not too worried.
Deal Addict
User avatar
Aug 12, 2007
4685 posts
805 upvotes
Waterloo
engineered wrote: I can tell you that running my 80% effect furnace which uses basement air, reduces the levels in my place by about 40% when it's running. My levels aren't too high so I'm not too worried.
So in the winter you have reduced levels?

whats the reading in the basement for you and above ground? or is it similar on both levels?
----
Pay it forward.
Deal Expert
User avatar
Dec 26, 2005
16932 posts
1780 upvotes
Thornhill
our Single day radon readings sometimes got to 180-225. We put in an HRV and were able to get it down to 80-125. I thought that was still too high and put in a radon fan to get it in the 4-10 range. Note that a radon fan is also much cheaper.

bjl
What we do in life echoes in Eternity... and in Google cache.
RFD discounts for Schluter products
Deal Expert
User avatar
Feb 11, 2007
15639 posts
16790 upvotes
Oakville
Supahhh wrote: So in the winter you have reduced levels?

whats the reading in the basement for you and above ground? or is it similar on both levels?
Yes, often lower in the winter compared to windows shut with the AC running in the summer.
I haven't taken the above ground readings in a while, but I recall it wasn't as low as I had hoped. Something like half the reading in the basement. Our basement readings fluctuate between 40-150bq/m3, but are often around 80.
Deal Expert
User avatar
Dec 26, 2005
16932 posts
1780 upvotes
Thornhill
engineered wrote: Yes, often lower in the winter compared to windows shut with the AC running in the summer.
I haven't taken the above ground readings in a while, but I recall it wasn't as low as I had hoped. Something like half the reading in the basement. Our basement readings fluctuate between 40-150bq/m3, but are often around 80.
Our long term average with HRV was around that as well.

bjl
What we do in life echoes in Eternity... and in Google cache.
RFD discounts for Schluter products

Top