3 ms·

Active sub-slab depressurization is only indicated if all the passive measures have failed. First, caulk the slab-to-wall joints, seal the sump pump cover to th

Active sub-slab depressurization is only indicated if all the passive measures have failed. First, caulk the slab-to-wall joints, seal the sump pump cover to the slab, caulk any cracks in the slab, etc. Then test again. What's the level you're trying to mitigate? https://www.epa.gov/sites/default/files/2016-02/documents/2013_consumers_guide_to_radon_reduction.pdf https://www.epa.gov/sites/default/files/2016-02/documents/20...

voisin 4y ago
It was up around 250 Bq/m^3 at its peak, and then I cracked open the two basement windows and it has since dropped to around 110 Bq/m^3. In Canada the recommendations are to deal with it ASAP if over 200, and to deal with it within the next 2 years if it is 100-200. I’ve looked and don’t see any cracks in the slab, but admittedly 1/2 of the basement is carpeted and drywalled and so I don’t have a good view of it. I use the AirThings View Plus, and note that it has been running for 2.5 months, and I want to see what it settles at as a longer term average.
- deleted 4y ago
  [deleted]
- myself248 4y ago
  > 1/2 of the basement is carpeted and drywalled Realistically, popping a hole in the slab and installing a fan might be less disruptive than tearing out all the finishing. Do you have a sump? First, seal it. Caulk as much of the wall-floor joint as you can. If it's still not low enough, add a fan _to the sump cover_, since the weep-tile system might provide all the sub-slab vapor communication you need without adding any new holes.
  - deskamess 4y ago
    Can radon come in through the walls? We recently got a crack in the basement wall and a small water leak. Will be fixing the leak next spring, but I am curious if this is a cause for higher readings. The long term average is about 135 but it occasionally spikes to 200+. Also in Canada.
    - myself248 4y ago
      Technically yes. It's a gas, so it'll permeate through anything that's gas-permeable. And being a noble gas, it's pretty small, not as small as Helium, but still it'll wander right through membranes that're gas-tight for diatomic molecules and larger compounds. However, that is almost always a rounding-error in terms of basement soil-gas infiltration. You can sometimes feel a literal breeze coming through a crack if the house is badly depressurized (windy day and stack-effect), you will never feel a breeze coming straight through a solid concrete or cinder-block wall. The spikes probably come from depressurization events like that. Sometimes the wind is angled in such a way that the house effectively forms a whistle or a manometer, and soil gas migrates at a greater rate during those times. This is somewhere that _passive_ sub-slab ventilation (drill a hole, connect a vent pipe to the outside, no fan) can often help significantly, along with caulking all the cracks. Seriously, don't bother with anything else until you've caulked.

voisin 4y ago

It was up around 250 Bq/m^3 at its peak, and then I cracked open the two basement windows and it has since dropped to around 110 Bq/m^3. In Canada the recommendations are to deal with it ASAP if over 200, and to deal with it within the next 2 years if it is 100-200. I’ve looked and don’t see any cracks in the slab, but admittedly 1/2 of the basement is carpeted and drywalled and so I don’t have a good view of it. I use the AirThings View Plus, and note that it has been running for 2.5 months, and I want to see what it settles at as a longer term average.

deleted 4y ago
[deleted]
myself248 4y ago
> 1/2 of the basement is carpeted and drywalled Realistically, popping a hole in the slab and installing a fan might be less disruptive than tearing out all the finishing. Do you have a sump? First, seal it. Caulk as much of the wall-floor joint as you can. If it's still not low enough, add a fan _to the sump cover_, since the weep-tile system might provide all the sub-slab vapor communication you need without adding any new holes.
- deskamess 4y ago
  Can radon come in through the walls? We recently got a crack in the basement wall and a small water leak. Will be fixing the leak next spring, but I am curious if this is a cause for higher readings. The long term average is about 135 but it occasionally spikes to 200+. Also in Canada.
  - myself248 4y ago
    Technically yes. It's a gas, so it'll permeate through anything that's gas-permeable. And being a noble gas, it's pretty small, not as small as Helium, but still it'll wander right through membranes that're gas-tight for diatomic molecules and larger compounds. However, that is almost always a rounding-error in terms of basement soil-gas infiltration. You can sometimes feel a literal breeze coming through a crack if the house is badly depressurized (windy day and stack-effect), you will never feel a breeze coming straight through a solid concrete or cinder-block wall. The spikes probably come from depressurization events like that. Sometimes the wind is angled in such a way that the house effectively forms a whistle or a manometer, and soil gas migrates at a greater rate during those times. This is somewhere that _passive_ sub-slab ventilation (drill a hole, connect a vent pipe to the outside, no fan) can often help significantly, along with caulking all the cracks. Seriously, don't bother with anything else until you've caulked.