I have concrete garage inside the hill below house level. Electrical metal conduit runs underground and enters the garage at the top of concrete wall. It may 12"-15" below surface. See pictures.

It's ok most of the time but during heavy and long rain, electric box inside garage starts leaking.

Electrician who installed it put some concrete around conduit but it's not a lot and obviously not enough. I dumped bucket of water there and I observed that leak happening.

So is there a good way to waterproof it? I am thinking - dig around the conduit, put something around it and then pout much more waterproof concrete (or whatever suitable material).

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  • Is the water coming around the conduit, or through it? If it's coming in around the conduit, duct seal should work. If it's coming through the conduit, duct seal might work. You'll have to clean up the conduit a bit, to get seal.
    – Tester101
    Commented Dec 19, 2014 at 1:49
  • It's definitely coming from around conduit since I just poured bucket of water there and saw it sip in. However, if conduit has joints and they are not sealed well, I wouldn't be surprised if it gets through it as well.
    – Uncle Meat
    Commented Dec 19, 2014 at 5:20

1 Answer 1


I have had need to seal up a few places like that in basements where the conduits came in and had a potential leak risk. On occasion I would use a Sika product, 2c-sl is the name Sika give it. A 2 part, self leveling, pourable material that can be painted on. I even made a form and poured it into that to ensure it saturated the crevices, since it was well below grade. This is good stuff. WR Grace also makes a 2 part liquid applied membrane that comes in 2 consistencies, trowel or knife grade. One is thick, the other thinner. I think either one will work for you. It is called Bituthene Liquid applied membrane. If you can get to Tremco products, they make a one part waterproofing solution, Tuff and Dri is all that I can find on that. They make another product that works really well, to bad I cannot find not more info on, other than I used it, sorry.

All these products are super flexible, and if you clean the wall real good you can paint that and the end of the conduit that the wire goes in to wrap it all in waterproofing.

Disclaimer: I do not work for or represent any of the above mentioned companies, I only know how to recommend products that do the job, and do it well.

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