A Little Home Civil Engineering Project

As I was working this morning, I heard JMD exclaim from downstairs, "Aw, crap!" Picture = 1K words, so to save space:


Yeah... basement flood time--lots of rain today (not freezing rain--once again, I'm thankful for the balmy east coast climate). The flooding wasn't too bad--it was contained to a portion of the basement, and everything we have down there is up on pallets or in plastic bins. But it was pretty cool to check out the spot where you could see water actively trickling out of a hole in the wall:


As a digression, since I'm interested in this topic:

Lesson 1: Basements flood.

As one of my coworkers once put it, "Why does it surprise anyone that you build a hole in the ground, and it fills with water?" Also, according to an insurance industry anecdote I've heard, 50% of basements flood to a depth of 1" or more over their lifetime. So that's why you should take measures (like pallets & Rubbermaid) when storing things in the basement. If you want to build a media room or library in the basement, there's a whole slew of work that I'd want to do before feeling even slightly comfortable with the concept (sump pit with backup pump, possibly exterior drainage mat if it can be retrofitted, or alternately an interior footing drain connected to a sump). If anyone's interested, I have some scanned articles I can email out on this topic.

Incidentally, cardboard boxes on concrete floor=total death. Even without floods, the concrete slab (if there is no polyethylene sheet of plastic under the slab) is likely to have some water coming through it at a slow rate. For instance, when you lift up a piece of rubber mat from a floor slab, and see a damp spot underneath--that's what's going on. In addition, a cardboard box functions as thermal insulation, creating a cold spot underneath--therefore, a greater likelihood of condensation. Another reason to keep everything up on pallets (air space -> no longer insulating).

Lesson 2: Basement Flood Prevention

If you have a basement flood, the first and obvious thing is to walk around the house while it is raining, and see where the rainwater is going. That's how to solve the majority of these problems. Disconnected or missing gutters and downspouts, water pooling around the base of the wall, ground graded towards the house instead of away, improperly drained window wells, melting snow--all of these can dump huge amounts of water into the basement. Philosophically, think of the ground as a roof extending out around your house, shedding water off it--if you have a leak through your roof, the wall's probably going to get wet.

I'd like to emphasize that finding and stopping these bulk water problems is the first and most important step. I don't think that any magic paint or sealant is worthwhile until you exhaust these big problems--they're not going to stand a chance against this much water.

In our case, the flood was being caused by the load of ice at the side of the house--water was pooling within/underneath it. It didn't help that we had a nice rainwater concentrator (read: downspout) right near there. FYI, the leak was located in line with the left hand side of the window.


So, using that lesson of "water runs downhill" (man... I knew that Civil Engineering Master's education would come in handy sometime), I realized that I had to cut a canal through the ice downhill to the driveway. By the time I had uncovered the bottom of the splash block, there was about 2" of standing water pooled there. Time to excavate...



I felt like I was chopping out a tiny version of the Gaillard Cut, but without the malaria (argh... how much further to Gatún Lake?). A scraper bar worked pretty well for chopping, although I think a pick axe would have made the job easier. Also, at the end of the exercise, I had enough impact shocks to my hand I felt like I couldn't really use my thumb for a few hours.

And hey--it worked! After the system started draining, I went downstairs, and water was no longer trickling out of the hole. The water is now soaking into the concrete.. my shop vac is in storage, and I figure nothing is really going to be hurt by the amount of water that's left.