Tag: rain

Unexpected Water Management

In my post about the sump pump, I discussed our concerns about water in the basement. Those concerns have proved well founded, because after some heavy Spring rains, it happened. Our interior weeping system directs water under the concrete slab to the sump pit and the sump pump pumps it away, and this system is working great. However, water doesn’t always come from below. Because of the thick, clay soil, water following the path of least resistance can come right through the brick basement walls. That water is coming in above the footer curb in the basement and then drains onto the top of the basement floor, bypassing the weeping system completely.

There are ways we could have avoided this. The preferred method is to excavate around the outside of the house and install a water barrier on the outside of the basement walls, but our house is less than four feet from the neighboring houses to either side, risking structural collapse of both our basement and theirs. Another method is installing a dimpled plastic membrane on the inside of the basement walls that provides a path for water to drain down below the slab and into the interior weeping system. We didn’t do that for a couple reasons. First is the potential for damaging the bricks, both from persistent water and from freezing. Second is that the membrane would have to wrap over the footer curb, and we’d have to frame walls in front of it, further reducing our floor space (by about 50 square feet). While we do plan to insulate inside the brick walls, we’re going to do so without a vapor barrier, so that the bricks can dry if they get wet. The interior-facing side of the footer curb will remain exposed, or at most covered by trim.

Old downspout accordion

Old downspout accordion

While we’re exploring ways to divert water that comes through the walls, the bigger focus is on keeping water away from the basement walls in the first place. Recently it poured, and I discovered that the downspout I’d put in after we removed the back porch was clogged, causing a fountain at the back corner of the house right where we were getting most of the water. Once I fixed that, the downspout was splashing about fifteen feet into the back yard… and then running across the patio to the other corner of the house. Worse still, our neighbors’ downspout was clogged and all the water from half their house was cascading into the gangway. The downspout we had on that side was running across the gangway and wasn’t sloped away from the house, so water was draining to the same corner. I got the water from both our gutters to divert to the stone-filled catch basin, but something more permanent was needed.

I ran to Home Depot and got some supplies, then got up on a ladder and reconfigured our downspouts. The gutter on the gangway side now drains across the back of the house between the first and second story, where it joins with the other downspout. It then drains about twenty feet from the house, but I plan to extend that to thirty. I also unclogged the neighbors gutter and ended the waterfall in the gangway. Since making this change we haven’t seen additional water, but I’m not yet convinced we’ve solved the problem. I have some other steps I can take if we see any more water.

Back Basement Steps Drain

Mario, our concrete mason, is planning to form and pour the steps and landing outside the back basement door soon. One important feature of the landing is a drain for rain and snow. I’m a bit paranoid about flooding in the basement. I’ve known too many people get water in their basement and cause thousands of dollars of damage to half-ass the drainage when we have the opportunity to do it the right way now. The good news is that even without any weeping system, the old basement never flooded, despite some heavy rainfall. The bad news is that was before we dug it down by a foot, and we’ve definitely had water at that level, though mostly due to bad gutters. I have extensive plans for storm water management with our house, but most of them haven’t been implemented yet.

Catch basin drain

Catch basin drain

Two of the people I know that have had flooded basements live in houses very similar to ours, with a basement door to the outside and steps up to grade. In both cases, water coming in from the back door was a major cause of the flooding, so I want to be extra careful with ours. First, the landing outside the back door is going to be a couple inches lower than the basement floor. Second, I’m using a 6″ catch basin style drain that ties directly to our interior weeping system. The advantage of this style drain is that any debris that gets past the grate settles to the bottom of the drain rather than going down the pipe and causing clogs or problems with the sump pump. Using a 6″ drain means that it will be more difficult for leaves and other debris to clog the grate. Third, rather than center the drain in the landing I put it towards the retaining wall, so that when Mario pours the landing it will slope away from the house. Doing that math on square footage of the stairs and landing, this system will easily handle the 3″ per hour 100-year storm water rate for Chicago as long as the drain doesn’t get completely clogged, and this drain should resist clogging.

Area drain installed

Area drain installed (looking out from basement)

The installation itself was pretty straightforward. We dug out the landing a bit and took out the old concrete threshold at the footing level of the basement door so we could run a trench to the weeping system. A bit of pipe, some stone, and the drain itself went in with a bit of test fitting and trench re-grading.

Ready for stairs and landing

Ready for stairs and landing

Mario came out and put in more stone to prep the area for the steps and the landing. We got some snow over the weekend and a holiday coming up, but hopefully we can get them formed and poured soon.