We have a detached 1954 garage on a concrete slab. The slab is cracked in many places and we get water in it during a heavy rain. Or, during this rainy spring, there's almost always water in it. As it slopes away from the driveway and there's no drain inside I either squeegee it out or wait for it to go back down the cracks naturally.

Is there anything I can use to prevent this? I believe it's just coming up through the cracks, mainly towards the rear of the garage. The yard is clay and holds water, after more thinking and watching I don't believe it gets high enough for the sill plate to let water in, it's coming through the garage cracks. hydraulic cement? Some type of epoxy?.

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  • At least from your pic, it appears to be coming from the walls rather than the cracks which suggests your slab or exterior sheathing is below grade. If that is true, you need to fix that.
    – topshot
    Commented May 6, 2019 at 16:58
  • @user20127 care to revisit this and tell us your solution?
    – user113627
    Commented Jul 13, 2021 at 15:24

1 Answer 1


You need to remove the water before it gets to the garage floor level. Since you indicate that water in the backyard may be so high that you suspect water coming thorugh the sill plate (i.e. above slab floor level) nothing you do that does not address THAT will really work.

So, standard approach (surround the garage with a drain, including a trench drain on the front to prevent rain from coming off the driveway into it, if it "slopes away from the driveway") will probably not be sufficient, if the water in the backyard is rising higher than the floor level. Drains only work if they have somewhere to take the water.

As such, you may need to address drainage in the back yard, unless you want to get into something as expensive and extensive as raising the garage structure and pouring a new slab floor, at a higher level, with a different slope to it.

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