clay soil in crawl space

shannonsull

We have clay soil in the crawl space under the house. One section is damp and probably caused from the sprinklers outside the house. We are going to move the sprinklers but how can we improve the soil in the crawl space to soak up the moisture and prevent future water from pooling?

WickedWarrior88

Add sand to the clay. Sand will soak up water. But make sure you mix it into the clay and deep enough to handle heavy rain.

AllanJ

You need to regrade the land so water flows away from the house.

Mixing clay surface soil with sand is more suited to preparing the soil for planting as opposed to controlling flooding. Once soaked into the soil the water still has to go somewhere.

Excavating the first 12 to 18 inches in from the perimeter all the way down to the footing bottoms (or down to more porous subsoil if you get there first) and backfilling with pure sand or gravel is superior to taking up a layer of clay soil over the entire area of the crawl space and mixing with sand.

Do not excavate all around a column footing such as used for deck support posts or houses on stilts. I am guessing that it is safe to excavate up to a column footing no more than on two opposite sides not getting within 18 inches.

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Red Squirrel

May have to redo the weeping tiles and foundation seal.... I just went through that, not cheap! You could also try regrading and that alone may help. is it only when you use the sprinkler or when it rains too? But redoing weeping tiles is best bet. At some time you'll get all that clay out of there as there is probably clay right up against the house, it does not absorb water as well.