Original question:
Before we bought our house, a moisture control system was installed on one side of our basement. The channel runs along the foundation and ends at a sump pump. This channel was filled in with concrete so the floor is unbroken. There is a black corrugated plastic sheeting that is embedded in the concrete right up against the wall, it runs the whole length of the channel to the sump pump. It sticks up about 4 inches out of the floor. Can I trim this off? I believe it allows air down into the channel so the water can run? That's a guess. It just catches everything and is hard to keep clean.
Update 4-23-16 – I was finally able to cover the plastic, I wanted to post a pic. Peeling away the plastic I could see the dampness behind it, trimming it flush with the floor would have been a mistake. I used a pre-painted 1×4 from my local big box home center, that is screwed directly into the concrete with concrete screws and finishing washers. The plastic trim acted as the spacer, so the 1×4 sits pretty straight. I then nailed a trim piece to the top to cover the plastic and seal it over. I plan on running a dehumidifier to keep the dampness down, so I wont be caulking the seams, which should allow the plastic to breath and hopefully dry out.
Best Answer
You're mostly right. The plastic is actually to catch wall water. But, if the wall is solid & tight to the floor, you'd be fine in trimming it, not removing it. If there are any weep holes behind the plastic, you need to keep those trimmed to their height & double their width so any weeping doesn't find it's way onto the floor.
If the wall's not tight to the floor & especially looks like a fairly even gap, then that needs to stay plastic covered as well. Use scissors though instead of a utility knife so you can't accidentally remove it. Since, you still need to leave about 1/4" above the tight floor to wall seam & above any openings.