Determined this is a 4 inch slab on top of original slab. Possibly with internal drainage channels from center of basement to edge, where it runs to pictured channel and sump pump.
House has channel all around basement leading to sump pump. Walls are drylocked. 1st course is poorly drylocked. Is this a standard and reasonable design? Alternately, was the design reasonable as implemented but now with apparent increased water flow, needs reconsidering?
Best Answer
I don’t like getting rid of moisture once it’s inside the house. I like keeping all the moisture on the outside of the house.
I see there is at least one crack in the concrete block wall (in the mortar joint), which will allow moisture in the house.
Water flows in the direction of least resistance. A channel design assumes moisture will enter the house and then “flow” in the channel to a sump pump. That allows standing water that can start mold, etc.
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 perfect 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.