View Full Version : Leak near radon vent in basement

Dec 31, 2006, 11:01 AM
Yesterday I noticed a leak in the middle of my basement, right where my radon vent enters the ceiling (see picture titled ‘Basement View - Note leak right of vent.jpg’). This is a passive radon system and the vent continues through the 1st and 2nd floor, into the attic and through the roof. It has rained moderately for the last three days.

I initially thought that I may have a roof leak, but when I inspected the vent in the attic I found no evidence of leakage. The exterior of the vent was dry (see pictures titled ‘Attic View #1 - Radon Vent on Left.jpg’ and ‘Attic View #2 - Radon Vent on Right.jpg’). The leak in the basement is located directly below the #1 attic picture, where the vent exits the attic floor. Since the radon vent bends 45° upon entering the attic from the basement (Picture #1), and then bends again 45° before exiting to the roof (Picture #2), a roof leak should be located at the second 45° near the attic ceiling, not the floor.

When I looked at the exterior of my roof, I noticed that neither the radon vent nor the plumbing vent stack had a cap on it (Roof View - Radon Vent on Left.jpg). This leads me to conclude that the rain water is running into my radon vent and somehow finding a way out after the vent descends below the attic floor. Does anyone else have another plausible reason for this leak?

If this is indeed the cause, can I just put a rain cap on the vent or should I try and find the leak somewhere between the basement and attic? The vent appears to run through a second floor utility closet (2nd floor) and a coat closet (1st floor) but I hate to have the rip up the sheetrock if I don’t have too.

I’d appreciate any thoughts on my predicament.


Dec 31, 2006, 12:45 PM
What else is just above where the radon vent goes through the floor? It could be another pipe is leaking, and the water running running acroff the floor and then through the hole aroujnhd the vent. Nothing is idiot proof, but I am guessing that PVC runs straight to the attic with no more than one coupling. Not a likely place for a leak.

Dec 31, 2006, 02:43 PM
What's your location and the weather temp at your home?
Define "moderate rain" by inches in a 24 hour period. Your pictures aren't titled. Topmost is the basement where the leak was noticed? Next the picture is a attic shot with the radon vent on the left hand side? The picture under that depicts the vents exiting the attic to the roof with the radon vent on the right hand side and the bottom picture shows me, what?? Two vents that have vent caps and two in the background that are not. I don't like to be forced to guess at what I'm seeing so if you don't mind please comfirm that my observations are correct. I'm with Labman on this. It's doubtful that you have a internal leak caused by rain water inside the radon vent. If I had to track it down I would start by taking a hose up on the roof running water down the radon vent before anything else got wet. Did it leaki? No? Then I would load the area around ALL of your vents with water and check some more for a leak. Still nothing? Now we get back to why I questioned the rain and temperature. I'm thinking condensate. Where warm humid air from the soil meets the dry cold of the attic. These are just off the top of my head but you sounded like you needed a place to start. Regards, Tom

Jan 1, 2007, 08:43 AM

I saved the pics with a name that described each but didn't realize this wouldn't show up in the post. This first pic is in the basement and is the location where I detected the leak. Note the wet subfloor to right of radon vent. The second pic (on the right in the post) is the attic floor. The PVC pipe in the upper left of the pic is the radon vent. The third pic is in the attic looking up. The radon vent in this pic is on the right. Finally, the last pic is an exterior roof view. The first two capped vents in the foreground are for the two furnaces in the house. The left PVC vent in the background is the radon vent.

I live in Greenville, SC. I just checked the rain over the last two weeks. We got 1.5” on 22 Dec, 1.3” on Christmas day and .62” New Years eve (last night). I first noticed the leak on 30 Dec when I was cleaning out a section of the basement in preparation for a renovation (obviously on hold until I can resolve this leak).

I like the idea of running water through the vent so see if it causes a leak. I plan to wait until it dries out a little so that I can verify whether the water running into the vent is causing the leak. It seems improbable to me that this vent would be leaking too, especially in an area that drops two floors in what I assume is a straight drop. If it is condensation what is the cure? Should I wrap the pipe in the attic or do you recommend something else?

Thanks for the suggestions.

Jan 1, 2007, 09:23 AM
Once you establish where the water is coming from, I would work at sealing where all the pipes and wires go through the floor and ceiling. Otherwise, warm, moist air can flow from the basement up around them into the attic, and then condense. I would also look at that copper pipe. Where does it go, and could it be leaking?