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cne24 09-18-2012 03:10 PM

Safe to seal exposed cinder block wall in basement?
Good afternoon.

I recently moved into an older house, built in 1977, that has what appears to be a cinder block wall foundation. Not sure how to describe it, but at about the 5’ level from the foundation floor, the cinder block top is “exposed” while the rest of the wall goes up to ceiling level behind the exposed row of blocks. I am not sure if the blocks sit on the foundation itself.

Though our home inspector saw no evidence of water intrusion, during moderate to heavy rains, there is some mild seepage in some areas where the block and foundations join, and one area has a small pooling of water. The seepage is on 2 of the 4 sides of the house; the other 2 sides remain dry (for now). When I look into the exposed cinder block openings on those sides of the building with a flashlight, I see some level of water sitting in the blocks on the seeping sides of the wall – the other sides, the exposed blocks are dry at the bottom. The blocks throughout the basement were obviously dry-lokd, which should have clued me in during the inspector process.

The grade on those sides of the house needs some work, and one side sits near a large deck that has no under-deck drainage, so heavy pooling occurs. I assume that proper grading under the deck, though seemingly difficult, would help with the seepage on that side of the house. Same with the other side (yard sloping, it was obviously graded years ago, but has deteroriated).

Time for my main question: assuming that the grading does not help with the seepage, what would happen if I poured a concrete mixture into the exposed cinder blocks in the basement? Would that effectively seal the blocks from water intrusion, or would that only make the problem much worse – as any groundwater would look for another point of entry and possibly force incredible force on/thru the foundation? I have no idea how deep the blocks go, or if they sit on the foundation – or what the typical construction at the time, with that material, was.

I’ve also looked at Hydro-Seal 75 as a possible addition to the blocks to combat the seepage, though it doesn’t solve the water in the blocks issue. The concern, along with the seepage issues, is a mold hazard as I have young kids in the house. Doesn't look to be an issue currently.

Thanks for any input.


cne24 09-19-2012 07:50 PM

Would it help if I posted pictures?

joecaption 09-19-2012 07:56 PM

Yes it would.
The problum needs to be addressed on the outside not the inside.
It would be near impossible to pore concrete or morter and fill up the blocks.

Working gutters, regrading or adding a french drain will do far more good.

concretemasonry 09-19-2012 08:14 PM

You must be from the east because "cinder clock" are really rare and are actually concrete block.

Without photos or a better description, a guess would be that the basement floor slab (probably 4" thick) is poured over and on the strip footing for the wall support and the water is coming from below for many reasons. The common sorces for the water to be able to leak in is the poor exterior drainage or a general water table and both of those usually are a period (hours or days) of time after rains.

Any surface correction is a "band-aid" approach that may work over the long term.

Water has the ability to flow laterally, following footings and loose backfill to the easiest point of entry downward. I had a home where the garage frost footings intercepted the natural drainage and water showed up 50' away in the basement. That happened while my car was sliding down the driveway due to warm tires on a fresh snow covered driveway.

Bottom line - you are looking at where the water shows up and not where it really enters the home footprint.

More information will generate more accurate solutions.


cne24 09-20-2012 07:43 PM

I'll post pictures soon. And, yes ... I'm on the east coast. In fact, I'm on the eastern shore, and I have wondered if the water table is the issue due to proximity to the Chesapeake.

Pics tomorrow/this weekend, and I'll try to elaborate. Like I said, I suspect the the grading is in fact the culprit. All gutters are working well, and existing drains appear to draw away from the house. Again, the issues are under the large deck and on a side of the house that there appears to be some erosion/degradation.


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