Hi everyone,

I’m feeling a bit overwhelmed and could really use some friendly advice or reassurance from anyone who has been through the foundation wringer.

We just had a historic 120mm rain event here that caused a leak in our basement. I didn't freeze, I immediately brought out a contractor and spent $3,000 to excavate, seal, and waterproof the entire exterior side of that wall to stop the bulk water.

However, after doing that damage control outside, we opened up the interior drywall cavity to dry out the framing studs, and we uncovered this behind the insulation. The concrete wall looks heavily honeycombed. In this specific spot, it looks like the cement paste never filled in properly when it was poured decades ago, and the aggregate is literally crumbling into a pile of loose gravel at the bottom track when touched.

We have a heavy-duty dehumidifier and a box fan running right now to get the wood dry, and I'm debating on whether or not I should call a structural engineer to get an official assessment. But honestly, my spouse and I are panicking about the potential cost and whether this place is turning into a endless money pit.

Has anyone ever uncovered a hidden structural concrete defect like this after already fixing the water issue? How did you handle the stress, and does a localized internal patch sound realistic once the engineer looks at it?

Thank you so much for any kindness or experience you can share!

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EDIT/UPDATE on the layout: Looking closely at the wider shot, I should clarify what we are actually seeing here:

• The left wall (where you see bare wood): This is an extension/addition that was added onto the home later.
• The concrete section: This is actually the original outside corner wall from when the house was first built.
• The opening on the right: This leads out of the mudroom into the rest of the unit.

My guess is that when the previous owners built the extension, the transition seam where the new wood wall meets the old concrete corner wasn't sealed or flashed properly. During that massive rain event, water must have funneled right into that seam, ran around the corner, and eroded this specific spot.

Knowing it's just an isolated corner junction rather than a continuous foundation wall makes it feel a lot more manageable?