Water Leakage in Basement

Hi All,

I had submitted a separate post about cracks in my basement floor, and wanted to thank all the responses I received. I also decided to do a post home inspection for a piece of mind as well as checking other items in the house.

Today, we had heavy rain fall in Ontario, and I noticed a small leak in the basement shown here: Basement Water Leak after heavy rainfall - Album on Imgur

This is the only leak out of my entire basement, and although it looks relatively minor, I’m wondering what’s the proper way to address this? I’m looking to renovate my basement, but I want to make sure I resolve all the water leaks before finishing it.


Correct the leak from the outside where the water is most likely coming from. Stay away from the people that want to re-direct the water from the inside.

Include your phone number here and Mark Anderso will see it or someone may direct your phone number to him. He is THE expert in keeping water out and may talk to you .


Hi Larry, thanks for the quick response. Is Mark in Toronto or is there a way to privately reach out? I haven’t started looking for contractors just yet. Just want to know what I’m dealing with first.

A crack in the foundation wall will allow rainwater to enter the basement. Waterproofing of the exterior is required.


Thanks Guys - Will look for a waterproofing contractor.

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No, Mark Anderson is not in Toronto. But, he may be helpful on the phone to you.

The key takeaway here is divert water on the exterior and waterproof the exterior oof foundation walls only. Like Larry stated @manderson7 is the best and has posted plenty of videos pertaining to this issue.

Just remember if anyone suggests
Dry-Lok as a solution remove them from your life immediately!

Good luck with your remediation :slightly_smiling_face:

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Repair of the cracking prior to applying the waterproofing is mandatory!!

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It’s imperative that the foundation be excavated first, prior to crack repair and waterproofing!
Since we are splitting hairs :laughing:

NEVER assume a contractor will do the right thing!! I have seen what some contractors consider waterproofing, and the shit they DO NOT do that any professional would never consider NOT doing!!

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Now that’s something we can all agree on.

I’m assuming the OP is NOT an HI or Contractor, but a homeowner looking for help.
We need to make sure we give full details as he will likely only know what we tell him, to avoid getting ‘taken’ by the lowlife scammers in the waterproofing industry!

Jeff, the plastic on the inside of the batt insulation and the batt insulation should removed. That small amount of water may be condensation because the moisture build up between the basement concrete wall and the plastic has no where to dry out to…it just builds up due to the dew point and cannot dry to the inside with the plastic there.

Really one should attach rigid foil faced insulation 4’x8’ sheets directly to the concrete basement wall and add wall covering to that with NO vapor barrier before the wall covering, in a basement.

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Jeff, this is a good detail to understand a proper foundation system. If a crack or seam is the appearant cause of infiltration then the detail should provide good insight on how the system should be, beyond repairing the crack itself.

That’s correct - Just wanted to get a general sense of what needs to be done before I went out looking for a water proofing contractor.


Now you have two choices.

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Larry, thanks for the comment. That’s a good point; the previous owner left many holes in the vapor barrier however (the photo didn’t do a good job capturing it), so it may not be a condensation. Definitely worth a look though.

Thanks Michael,

Looking at this detail, it doesn’t look my my foundation wall follows this. I don’t see the insulation 8" above grade, nor do I have a waterproof membrane (at least from what I can tell). Here is a photo of the area in question on the exterior: https://i.imgur.com/zy974Wi.jpg

On a separate note, the leak looks like it’s in the vicinity where the AC unit is…this is going to be a pain in the ass to excavate.

Most likely you have “Damp proofing” and not “Waterproofing”. Huge difference!!

Yeah that’s going to suck. Big time!