Starting the trench

Starting the trench

After we got the basement dug out, we were planning to have the weeping system put in by our plumbers, but the plumbing quotes were all so high that we had decided to do the weeping system ourselves to save money. I started with some Internet research, followed by a perusal of Chicago Building Code. I also watched an episode of Mike Holmes putting in an interior weeper. Finally, I spoke to the plumbers to see how they typically do it.

Slow progress

Slow progress

I recalled my architect telling me that the weeping trench had to be twice as far from the footing as it was deep to prevent undermining the footing (since we’d dug to the bottom of the footing). Since we’re using 4″ drain tile pipe, the minimum trench size is 6″, so it’s set 1′ in from the footings. The plumbers said they typically dig the trench a foot wide, but I was at a shortage of places to dump the dirt and I didn’t want to dig more than I had to. Plus, I didn’t see much of an advantage to making the trench wider. I initially started digging the trench an even 6″ deep, but I realized that the pipe needed to slope toward the sump crock by ⅛” per feet, also known as 1″ per 8′. I started with the depth of the sump crock openings and worked backward. The result put the top of the pipe proud of the trench in places, but still within the stone that goes under the concrete and foam insulation.

I bought a big 36″ deep by 24″ wide sump crock, rigid PVC drain tile pipe, a bunch of assorted fittings, and a pipe filter sock. The plumber suggested I account for the front bay window with some 45° fittings, but because of how sharp our bay is compared to most, I wound up using street 45s plus 22.5s for “67.5” degree turns. In my previous post on the mechanical room layout, I alluded to the challenges of figuring out where the sump basin would fit without interfering with pipes for the ejector pit, the sewer line, the pex tubing that will eventually come out of the floor by the radiant system, and without the outlet pipes being in the way of the boiler. I settled on an area along the wall that’s in front of the radiant panel, but not where the pex will come out of the floor.

Finished install

Finished install

One of the advantages of rigid PVC drain tile over the corrugated stuff is you can snake it if it ever gets clogged, so I added a clean-out at the far end of the run, as well as a connection for the drain in the back steps landing. The hardest part was digging the trench and sump pit and hauling out the dirt. Once I had started putting the pieces into place, assembly went quickly. The last step in the process is our sump pump, but I still have to plug it in, so I’ll cover that in another post.

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