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Original question: photo of wall with plastic trim

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 1x4 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 1x4 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.

photo of wall with plastic trim covered

  • Can you post a picture? Or, any chance you could contact the installer? – Daniel Griscom Mar 5 '16 at 20:00
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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.

  • The idea of weep holes behind that plastic never occurred to me, but of course it makes perfect sense! I really appreciate the excellent response. I will inspect and trim it accordingly. – Brenden McDougal Mar 6 '16 at 2:31
  • That's why I'm here & thank you for asking for others. Thanks for the picture too. If you find that you'd rather not trim it, you can beautify it by either hanging baseboard from it or by screwing into just the plastic, not into the wall, as lightweight as possible. I'd go with a thin flat board or 1/4" plywood strips for the front to sit on the floor hung or attached with very folded L-brackets or even reversed self-stick picture hangers. And then, do a quarter-round or other decorative molding glued on top. This needs to breathe so just tack-weld with caulk. – Iggy Mar 6 '16 at 11:31
  • Thanks Iggy, covering it over is not a bad suggestion at all, it could look like it's not even there. I assume the way it's installed is pretty standard? – Brenden McDougal Mar 6 '16 at 18:08
  • Going vertical up the wall is for fairly minor seepage types of previous problems. An open channel on the floor filled with gravel is for serious flooding issues. But, you should be able to dress it up pretty well. – Iggy Mar 6 '16 at 20:55

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