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Community and Q&A

Sump pump installation cost

Poliana | Posted in General Questions on

Hello everyone, My crawlspace has water. We installed gutters, regraded the ground and still have water. Next step is to check the footing drain. The builder came with this idea to have a French drain built in the area where the water comes into my crawlspace. I told him that we want a functional French drain that drains out any ground water and not a short cut which would be the French drain. Also, the whole perimeter of the rat slab is wet, but the water comes in from two places. We also are thinking to install a sumpump, but the estimate was a bit high: $18,000. The company is highly appreciated and recommended by so many people around me: ” Based on my findings in your basement In order to ensure you are going to get a lifetime warrantee I want to pour the slab you don’t have a very thick slab now so possibly I the future it would leak with a different type of system  With the new slab I know for a fact that it will not leak ever and feel confident giving you that warrantee.” The builder said “I appreciate that you have looked into the sump pump and internal drainage system, however the estimate that this company is giving is well over twice as much as the numbers that I had gotten in the past. I find it very suspicious that they are asking 18, ,000 for such a small basement. Looking through their fine print they do not even include extending the discharge lines away from the house or running electric to the unit, they also do not describe or guarantee any cleanup or dust mitigation. ” Please let me know your thoughts

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  1. Expert Member
    Zephyr7 | | #1

    $18,000 for a sump pump sounds awfully high, but I don’t know what their scope of work is so it’s hard to say. I’m going to assume some amount of sawcutting of the crawlspace or basement concrete slab, some excavation for the sump, and some excavation for a discharge line. If they are also cutting in drain tile in a crawl space or some other kind of perimeter drain that would be a LOT more work.

    Be absolutely sure they include cleanup in their contract. Any indoor cutting of concrete tends to make a huge mess and you don’t want to be stuck with it. I’d also require them to do “wet cutting”. Wet cutting will result in the saw throwing a slurry of concrete gunk that will need to be cleaned up, but it’s much better than having clouds of very fine concrete dust going everywhere. Dry cutting is just about as much of a cleanup nightmare as sanding drywall.


  2. Expert Member
    Malcolm Taylor | | #2


    The logic behind pouring a new slab because the old one (commonly called a Scratch Coat or Rat Slab) is too thin escapes me. The thickness of the slab has no connection with the ability of water to infiltrate the crawlspace. Unless there is some other defect in the existing slab, it makes no sense - and probably represents a large part of that estimate.

  3. Jon R | | #3

    You should also verify that you have an impermeable top layer of back fill (or underground roof) around the house perimeter.

    1. Poliana | | #9

      What is underground roof?

  4. matt9923 | | #4

    You have a few topics going. From what i read you have a warranty and someone coming to inspect the footing drains next week. Having groundwater migrate up through the crawlspace slab would be rare with proper grading and footing drains. I appreciate your motivation to fix the problem but your not at the point of spending 18k more in my opinion.

  5. Walter Ahlgrim | | #5

    Waterproofing contractors all too often bid high if they think they can get away with it.
    I still think the problem is in the exterior drain that would be the best fix. It is a big bet to dig them up and hope to find something wrong.

    How much rock is under the slab? If you have several inches of rock it should not cost much skip the interior perimeter drain install a sump and a pump.


  6. Poliana | | #6

    The architect wants to dig up and check the footing drain. He wants to fix the problems from outside.

  7. Brian Pontolilo | | #7


    When you you say that the who perimeter of the house is wet, are you saying that the ground around the house is perpetually wet? Is the site sloped toward the house? And where does the water come in?

    1. Poliana | | #8

      Thank you for pointing it out. I wanted to say the perimeter of the rat slab. I don't know how to correct the mistake.

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