Does a concrete floor provide any resistance to ground water?

I have an addition that was constructed to extend my house 8 years back that has quite a large basement room. Unfortunately, this room does not have a concrete floor and has a dirt floor with about 2’ of crushed stone on top; a perimeter drain and a sump pump is also installed. Just to give some context, this dirt floor is about 17" lower than the finished concrete floors in the older basement rooms and when pouring a floor I’m considering comming up another 8"(4"crushed stone+4"concrete).
In the last 4 years that i have owned the house, I have had a few incedents where the sump pump has failed(variuos reasons from stones clogging the impeller to broken pumps). At these times I have noticed that the room floods in the rainy/thaw seasons(not when the ground is saturated). The waterlevel in the room can be as high as 12" from the dirt floor. We all know that water takes the path of least resistance,** so my question is if adding a concrete floor with a moisture barrier(eg: poly) below the floor provide enough resistance so the water travels elsewhere? My thought is that adding the floor will be enough to prevent the room from flooding in the future if the pumps were to fail say in case of a power failure.** Rest assure I’m planning to run the pumps, but just worried for those unforeseen failures.

I would imaging eventually the water would penetrate and wick right through it.

I have a headache and just read the question and not the whole post :slight_smile:

If you are on town water why not put in water power back up .
Protection in case of power loss or existing pump failure .


In my opinion, I would add some drainage under the crushed stone first. If it’s a dirt floor it will be relatively inexpensive to do. Before your floor goes in you have to deal with the water. If you don’t and have to deal with it later it will be a pain in the ***** and a lot more expensive. Moisture is the enemy and we must be vigilant, ignoring it will not make it go away.

It’s not that simple but it will find another way into your house.

Water coming up to a solid surface and trying to rise creates hydraulic pressure under the floor. Enough of this and the floor can be heaved. Drainage below the concrete floor must be in place.