Radon mitigation question
Will an interior footing’s corrugated drainage pipe be sufficient for moving radon, if the footing & pipe is almost 24″ below the slab height for about 50% of the perimeter? Or does it need to be near the vapor barrier to be effective? There is a haunch that will separate the slab essentially in half, except for about 2′ on each end. The vertical exhaust pipe is on the opposite side.
We’re trying to decide if it makes sense to run another perimeter length of pipe near the top of the stone aggregate layer in this rear 50%, as it is for the front 50%. Or, if the 2′ on each end of the haunch + the footing drains pipe will be sufficient to allow the radon to vent.
Our slab is 4″ concrete o/ continuous 6 mil poly o/ continuous 2″ EPS type II o/ 4″ stone.
This will be my own house, and I’m not overly concerned as I’m not in a particularly high radon area, but I would like to make sure that our passive venting is effective. The slab is ready to be poured, so changing anything means tearing up the poly and foam board to make this change. Time consuming & frustrating, but not costly.
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Hi Matt,
Have you read this? It may be helpful.
https://www.greenbuildingadvisor.com/article/all-about-radon
Hello Brian,
I did read that article right before posting. The consensus I get from all literature so far is if you have 2 separated slabs, for each one stick a 3" pipe + T into the stone through the slab. Maybe run some horizontal.
We don't have an elegant way of doing this. And if we do it would require running a whole other vent through the roof.
We also don't really have completely separate slabs.
I think the answer is 'Maybe it will work' as it is.
And 'It will probably be better to add more pipe'
I can't picture your situation without a drawing, but the underlying principle is that there shouldn't be much resistance to mitigation air flow to any point in the stone under the foam.
I agree - when in doubt, add more pipe.