Waterpoofing basement

I’m getting part of my basement finished soon. I have a couple spots on the wall where a little water leaked (one time in the 7 years we’ve been here, after some really heavy rain). We bought from the builder, and had a bunch of other spots fixed, and I watched the guy do one of them. He kind of picked at the concrete to remove loose concrete, and used a (silicone?) caulk to seal the spot. None of the repaired spots have ever leaked again.

When I watched houses being built when I was a kid, the concrete forms were held together with metal strips, so I figure there’s one there, rusting a little bit. So I go ahead, and start picking at a spot, and it seems like I loosened a stone. I get it out, and it turns out there’s a 5/8th inch diameter hole, going all the way through the wall. They just put in a half inch plug of concrete or mortar after they pullled the forms out.

I’m thinking of filing the hole some kind of caulk or tar or something, two to four inches deep. What would the best material be? Or is there some other approach I should be taking?

The holes are about chest height, and we have footing drains and a sump pump, so there isn’t too much water pressure behind the holes. I’ve never seen any evidence of water leaking through the walls, except at these spots.

I don’t know what the code is where you are, but where I am (and I spent a few years of my life forming basements) we use a heavy patch, like roof tar, to seal the outside of the snap-tie holes prior to coating the entire exterior of the basement in tar. I would use that or some sort of expanding grout which is made for patching holes in basements.

Hydraulic cement?

You can do exterior waterproofing which is more expensive and disruptive to grading and plantings but quite effective, or attempt interior waterproofing. The downside to interior methods is that you’re causing the moisture to look for the next weakest spot in the wall, as opposed to placing a barrier between the exterior wall and grade.

Thoroseal® and Waterplug® are two good products for interior side application. Check with local concrete suppliers to find out who stocks or can order it. Searching for either product by name will bring up data sheets, among other links.