What if I have a leak from a pipe after I have my crawl space sealed up? I will have a swimming pool under my house, should I have some kind of drain installed in the vapor barrier?
This question usually arises after meeting with a franchise company that sells a drain for their vapor barrier system. The product pitch is designed to settle a fear of what if my crawl space gets water in it from a frozen pipe or broken water line. The drain is designed with a ping pong ball under a drain cover that will float when water enters the drain. Once the water is gone the ball then returns to cover the opening leaving the homeowner with the understanding that they will have to do nothing for clean up. Pretty ingenious if you only look at the pro’s of the design.
So lets take a look at the con’s to better determine if a drain in the vapor barrier is a good idea. The same mechanism that allows water to enter the drain, the ping pong ball, will also allow the water to enter your crawl space from under the vapor barrier. If the power goes out and your sump pump is temporary not pumping water and the water backs up, then the ping pong ball will float and allow water to get on the barrier. In this scenario the water will be dirty allowing mud to settle and making the clean up a much bigger job.
Another major flaw in this design is what if the drain is on the west end of the crawl space and you have a leak at the east end? Unless the drains are placed throughout the crawl space under each bath, kitchen and laundry it is not likely the water wouldn’t go into the drain in the first place. In order to fix this ‘what if’ it causes more compromises in the barrier and in many different locations.
Beyond these two problems, if the crawl space is sealed properly the threat of frozen water lines is very unlikely. Frozen water lines is a condition of an open crawl space not a closed or conditioned one. Which is what you would be paying for, so why the back up plan? Moreover, the chances of a power outage happening during a heavy rain storm is far more likely. This situation causes the threat of water entering the crawl space, while the sump pump is down, and then making the chances of water entering through the drain a real problem. This problem is probably one of the reasons you were talking to them in the first place. In my opinion, the sales pitch diverts the focus of the real threat to a “what if” situation to build confidence in a product line. Know this, sales pitches are designed to really accomplish one thing- psychological dominance. To present, convince and close the sale. The drain is not the focus of the pitch it is an example of setting a fear and presenting a solution to build confidence in the system.
So what do you do if a pipe breaks or the washer over flows? I say handle it “IF” it happens. By cutting a small slice in the crawl space vapor barrier to allow the majority of water to drain into the drain system or under the barrier. By doing it this way you can drain the water where the water is and not have to push it to a fixed drain. Then once the water is gone and you have mopped up the last puddle, tape the slice with the same tape used to seal your lap seams. This gets you as good as new and the option to simply remove the tape “IF” it happens again. This process handles any real problems not just the threat and it does not cause any new ones.