I've been recommended by two companies now to install an interior vapor barrier along my basement walls to prevent the water that is shooting out during heavy rains. The vapor barrier will stop water as soon as it passes through the concrete blocks and fall into the perimeter drain which leads to the sump pump. While I'm comfortable taking this route to prevent flooding in my basement, I can't help but worry about potential issues that may arise if I'm not preventing water from first entering my basement walls.

Am I overthinking this situation? Or should I consider sealing the exterior side of the basement?

  • You're right that exterior mitigation is better. What's the question?
    – isherwood
    Mar 31, 2021 at 19:21
  • Define "overthinking" To "Consider" does not cost anything. Doing may or may not be expensive. I say consider ALL options before taking action.
    – Alaska Man
    Mar 31, 2021 at 19:24
  • 2
    If you are willing to spend the money to dig up outside the walls, and perhaps even further upslope in the yard, that's "better" - if you have terrain that allows running a drain with no pump needed while doing that, better yet. End with the slope of the soil surface AWAY from the house for at least 10-12 feet when complete. For a quick-to-implement lower cost solution, the interior baffling to the sump is something.
    – Ecnerwal
    Mar 31, 2021 at 19:25
  • These companies have a product that they want to sell you, you are right to be skeptical.
    – Jasen
    Apr 1, 2021 at 6:31
  • Is the water really passing through the cinder blocks, or is it coming between them due to cracks and aging of the original concrete or cement used to build the walls? Apr 1, 2021 at 15:42

2 Answers 2


Providing proper drainage outside combined with sealing is my preferred method. I have had walls that may have been close to what you have I dug down installed drains and backfilled with rock (no dirt) that home went from rivers on the floors to dry walls. If possible to divert the water before it enters it takes less energy to have a comfortable basement in the winter (sump not having to pump all the water out of the house that came in to me that made sense it worked quite well so over thinking it? No I don’t think so but this could be viewed as an opinion question.

  • Definitely agree.
    – JACK
    Mar 31, 2021 at 22:51

I don't think you're "over thinking" the situation at all. "Water that is shooting out during heavy rains" is not something that should be neglected. Yes, you have drain tiles and a sump pump but power goes out and batteries to run the pump can prematurely discharge; now you're flooded.

It seems to me that if the basement isn't finished (because two companies want to install vapor barriers) you could locate probable areas that are leaking and seal them off. That, combined with some of the other suggestions, would be a logical (Mr.Spock) course of action.

  • Yeah, "water shooting out" is a bit of a red flag...
    – FreeMan
    Apr 1, 2021 at 16:23

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