I had water leaking in my cellar from bottom of floor. Water was NOT on blocks at all. Now after French drains and weeping holes put in, the cinder blocks along the bottom of floor are wet. Will this damage my foundation, over time?


It sounds like your water table is very close to the floor level. It's not necessarily damaging to the concrete, after all hydration is what actually cures concrete and concrete peirs are largely unaffected even after hundreds of years sitting in water. Lumber and your possessions in the house are of a concern. I would suspect that you would benift from at least a sump pump and even better, a weeping system tied into the sump pump.


If the weep holes are admitting water, there must have been water in the block wall as well, and it was probably hidden by previous water sealing of the walls. Still, if the block wall had a course below the slab, the weep holes should have been drilled there when the perimeter had been removed to install the french drain, so this water wouldn't be visible above the slab.


Yes, the water leaking into your cellar can cause problems like mold, and decay of mortar, etc.

Sounds like the French drain was not installed BELOW the basement slab.

Water flows in the direction of least resistance. You have now installed a perf pipe that collects water by the wall...then, because the water has been collected above and next to the slab, it can seep into the basement.

Moisture is either coming up from below (a rising water table) or its coming from the surrounding ground water in the saturated soil.

If it comes up from a rising water table, it will enter the living space from below through the crack between the foundation wall and slab.

If it comes from the surrounding ground water, it COULD enter the living space through the wall, especially if the EXTERIOR side of the foundation wall is not sealed properly. Either way the moisture enters the living space it will need to be collected and disposed. I think the best way to collect it is on the exterior side of the foundation wall in drainrock and a perf pipe laid 6”-8” BELOW the interior basement slab.

To keep the subsurface water from seeping through the wall, I recommend installing a moisture barrier on the exterior side of the foundation wall and install a 2” thick plastic mesh on the wall to allow water to flow down to the perf pipe. If dirt is allowed to be backfilled against the wall, the dirt could hold the moisture giving it a chance to seep through the wall.

Once collected it needs to be disposed by extending a solid pipe over an embankment or in a collection well and pumped away.

This may be the most expensive method of solving the problem, but it’s sure to work.

  • No, moisture in a slab is not a problem other than mold and high humidity. I have had homes in multiple states with basements the oldest 1922 very wet basement. It had awesome French drains around the premier my dad bought the property before he passed I put them in but there happened to be a spring under a 6” slab that was poured prior to our purchase. A house older than my dad still stands today French drains did not help in this 1 case. What did help was an engineered coating on the slab that was prior to 2 part epoxy paint after that there was no problems, mom sold that when I enlisted. – Ed Beal Aug 30 at 2:33
  • @EdBeal I’m glad you agree with me that mold can be a problem. However, excessive moisture in a masonry wall can also be a structural problem. Just read this: buildingsolutions.com/industry-insights/… You say, “...moisture in a slab is not a problem other than mold and high humidity.” Moisture IN A SLAB is not the question. The OP is asking about moisture in “the cinder block” WALL and FOUNDATION. Again, it’s not the slab, it’s the wall. – Lee Sam Aug 30 at 2:56

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