It was while I was in the middle of framing and insulating my basement that I first found the mysterious leak in my basement. One sunny day I was happily putting up steel framing and when I returned the next rainy day I found a pie-plate sized puddle forming right where the basement foundation and cinder block walls met.
My basement has always been bone dry until I found this leak, which suddenly had me wondering if I should even bother to refinish my basement because anything I did down there might be subject to flooding or water damage. This had been a particularly wet season with a lot of melting snow followed by a lot of rain, so I wasn’t sure if it was just something I had never experienced or if this was a genuinely new problem that wasn’t there before.
Before I became too worked up I decided to see if I could simply figure out what was going on. I lined up my suspects and methodically examined each one.
Suspect#1 – A Leak In The Basement Foundation: I didn’t actually see any sort of a crack or split between the wall and floor but we had received a lot more rain than usual so I figured the water had to be coming down off the roof, pooling somewhere on the ground near, seeping into the earth and coming up through the foundation along an edge.
I went outside and surveyed the situation. I didn’t see any obvious drainage issues outside and the new vinyl gutters that I installed myself seemed to be working well. I figured I could try to regrade the back yard a little bit or maybe route a gutter further away from the house, but I wasn’t sure if that would really make much of a difference in the long run.
About a week later we were subjected to another prolonged down pour. I went down in my basement to check the progress and to my horror I found more water on the floor! But while I was looking around and feeling the leak I noticed something: there were water droplets on top of the steel plate I had attached to my concrete floor during that week. Water droplets on top of the plate could only mean one thing: water was coming DOWN onto the cement, not up through the floor! This led me to my next guess…
Suspect #2 – The Toilet Above is Leaking: I looked up and realized that the entire leak was right over the spot where my home’s clean out valve was located. And what was right above that? A small bathroom with a toilet! Excited I ran upstairs and poked around, but found no leak around the toilet. This sort of made sense: my toilet wasn’t running randomly and it didn’t seem to be losing water or doing anything else strange. So I used an old fallback method that I often turn to when I’m stumped with a home improvement project: I called my dad.
He and I talked it out a little bit and while I was talking to him I started feeling around the main drain pipes. Sure enough, I found a few drops of water that were out of view behind the pipe. My father also ruled out the toilet and even the washing machine above me. He figured it was related to the rain because that seemed to be the only time that I had the leak (I had forgotten that little fact when I was poking around the toilet).
Suspect #3 – Leaky Roof Around The Vent Stack: My father suggested maybe there was a leak at the top of the vent stack, where it pokes out of the roof. The vent stack is basically an air pipe connected to a plumbing drain system that allows air into the system so that water can flow out of the system freely. If you’ve ever tried to pour gas out of one of those red gas cans without popping the air vent you’ll notice that sides of the can suck inward and eventually gas will stop flowing if air cannot slip in to replace the flowing gasoline.
The vent stack in most homes exits through the roof. Yes, those are those white pipes that stick out about 6 to 8 inches high on most roofs. The vent stack runs straight down the interior of a house, from the roof to the basement and right to the clean-out valve where I was seeing my leak.
Rain coming down into the vent stack isn’t a problem: it just goes into the plumbing drain system, but rain rolling down the roof and dripping down around the outside edge of the vent stack could be a problem.
1. The puddle in my basement only appeared during heaving rain.
2. The water was coming down the vent stack (I could feel the water on the back of it)
3. No other plumbing device above that part of the basement seemed to be leaking (as far as I could tell)
Having nothing else to go on, I decided to check it out. When the first sunny weekend rolled around I was ready. I grabbed a tube of Roof and Flashing Sealant
So I got to work spreading the roofing sealant all around the old rubber seal and vent stack. I used a caulk gun to squirt out a few inches of sealant and then used a free paint stirring stick to spread the sealant around like I was icing a very sticky cake. The idea was to basically make a new solid piece of rubber that was waterproof and water tight around the vent stack. The other three vent stacks on my roof weren’t quite as bad, but I still sealed around them as well as I could.
I only had to wait about four days to get another solid downpour of rain that lasted several hours.
The verdict?
Suspect#3, the Leaky Roof Around the Vent Stack, appears to have been the culprit! My home has now gone through three solid days of rain without a single drop of water in my basement!
Case closed!
This is a typical example of DIY, some basic understanding and product knowledge definitely helps.
Basement leaks are tricky but what is important is you fix the leak before finishing off your basement. If you have a crack in your foundation, fix it! If you don’t have a crack, seal it! Finishing a basement can be costly but repairing a finished basement costs even more. There are many great products out there that make sealing and fixing a basement easy.