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Community and Q&A

Crawl space drainage

groundwater | Posted in General Questions on

The best I can tell there is a spring (seep) under my house.

This is not an uncommon is our area. Most everybody has a spring or seep in their yard or around the foundation or both.
The crawl space currently has a sheet of plastic and a sump pump tied to the sewer. ( we bought it this way) I am wanting to change this to a gravity drainage system. Dig out about 4-6″ of the dirt, install a perimeter trench and a channel from the seep with drain tiles, cover with gravel and dimple board, then run the drain line under the foundation to daylight. Excavation under foundation would be grouted with Ready bottom of footer.

The rest of the plan is to redo the exterior foundation and downspout drains also.

eyeballing it we have enough grade for the back and right side to make it to the storm drains. In a few days we are going to shoot elevations to make sure we can get 2-3% grade on drain lines on the left side of the house. fi not we have 2 options 1. tie into the back. 2. dig up the driveway.

my main concern is going under the foundation. I have never done this before and all my construction experience tells me it should work. Emphasis on should. Ya’ll have far more experience than I. Would appreciate any thoughts and horror stories. Any questions please ask.


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  1. Expert Member

    We do it all the time. It's a good idea to use flexible rubber couplings on each side to avoid cracking if the pipes settle.

  2. GBA Editor
    Martin Holladay | | #2

    I agree with Malcolm. Excavate what you need -- no more -- and pack the soil or backfill material in tightly around the new drain pipe, and everything should be fine.

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