What's this?

[gtblum]

Is this anything other than an expansion joint?

It's a brittle corrigated plastic material that looks and feels like the stuff used for fill pack in cooling towers. It runs the perimeter of the basement floor. Home was built in 77.

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[resqman]

Looks like stuff used to today as a way to drain water around the basement walls.

It is perforated so water flows into the vertial spaces and falls down to the drain pipe at the footing. That way water does not sit against the foundation wall and try to migrate through.

[kurt]

Yep. Looks like an air gap. Any water that squeaks through the walls seeps down to the drain tile instead of out over the floor.