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Community and Q&A

Dimple mat down the inside of basement walls?

iced98lx | Posted in General Questions on

Hello, long time follower, first time caller.

I’ve got a block basement that was previously finished (really poorly) and due to some “events” is no longer finished. The basement has had drain tile installed internally but the walls occasionally have some minor seepage, and where the block meets the slab has some seepage. No other water pushing up holes in the slab so it seems to be draining OK not at the walls (unless I’m not understanding). We aren’t interested in re-finishing the basement but we do want to get it to the point where it can be finished. I am unable to excavate outside and dimple mat the walls and put in an external drain setup like I would like to (for a few reasons) so I’ve hatched a plan to run dimple mat down the inside walls, break the floor where it meets the wall and run the mat into the gravel for the drains, then concrete up to the mat on the floor.

Basically, capture any water coming in the walls and drain it down into the existing drain system. 

Good idea, bad idea? Other ideas on how to handle it?  All input welcome.

EDIT: Basically this I guess:

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  1. Expert Member
    BILL WICHERS | | #1

    That’s not an uncommon way to do it, actually. There is a product of British manufacture ( that is actually designed to be able to work with a dimple mat on an interior wall.

    Sometimes you can accomplish the same thing by drilling drain holes into the interior holes of the bottom course of block, then applying a waterproof coating to the interior side of the block wall. The drain holes allow any water in the block to drain out, and the water proof coating keeps the rest of the wall dry.


  2. iced98lx | | #2

    We've got a basement systems dealer here in SE South Dakota but to add their drain on top of the already in place drain tile would be $6k and they don't want to use dimple they want to use flat plastic film (60mil) which isn't as good for drainage to me on the walls (another $6k!). All told they quoted about $17k for their gutter, plastic on the walls tucked into said gutter and upgraded SUPER DUPER sump pit.

    Thanks for validating that I'm not out in left field here Bill, since the drain system is already there I'd hate to pay to put in a new one so me thinks the concrete comes out and the dimple goes up.

  3. Expert Member
    BILL WICHERS | | #3

    The guys at that link I posted will happily sell to US customers so you can install their products DIY if you want. You’re not locked into one of their dealers.


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