Greetings, folks!
I understand that a lot of homes use some sort of vertical stack radon removal system, where there is like a plumbing vent stack going down to a sealed sump in the basement, which is open to under-the-foundation.
If one was to build on a sloping lot, however, why not just bury some PVC with one end in the gravel under the slab and one end lower down, venting to the outside? With Radon being the heaviest gas, any water or radon building up in the gravel should then just drain to the outside… (See extremely basic diagram, below)
Am I missing something, or is this logical?
Thanks!
Legend:
Tan – dirt
Light blue – vapor/moisture barrier
Yellow-with-dots – gravel
Dark blue – drain pipe
Replies
jaime
Not far fetched.
We built into a hill in '89. Took me a yr and a half after union work and weekends. Long time to deal with draining the interior. Thought like you did. Ran the pipe around the interior of the exterior foundation and also through the dimising foundation-to daylight.
Kept the interior workable till roofed, sided, and windowed. The radon drain was a plus as there are radon areas around here and did dig up some shale while excavating.
Makes perfect sense.
Passive radon removal systems similar to what you drew up were installed in the 70s and 80s. I do remember them not performing well though. The gas simple doesn't exhaust throught the outlet. My recollections come from magazines like Mother Earth and New Shelter.
The systems that worked were the ones that moved air, and those required a fan.
I have a set-up similar to yours with one difference: the serpentine run of 4" perforated radon "vent pipe" below my basement slab stubs out through my slab and into the basement in a rear corner of my basement. The stub-out is capped.
Right now I have a passive system. I doubt if it's doing any good whatsoever, but it's there. But when I built this place, installing 4" pipe was cheap insurance. If I ever needed an active system, I figured I'd set an enclosed fan on the 4" stub, then run a bit more 4" up and out the rim joist of my house. I figured if I could find a decent solar powered fan I could have the panel outside and the fan in the basement sitting on the stubout.
Air would be drawn from outside the house, through the rim, through the fan, through the stubout, and under the slab, then exhaust out through the pipe that runs to daylight. My daylight pipe is very similar to your drawing.
I've tested for radon a few times over the years, no worries so far. I did have to blast ledge in one corner of my foundation hole.
Thanks for the thoughts so far! I certainly appreciate them and will consider what you say.