Misconception: A Sump Pump Will Dry My Crawl Space

Will a sump pump by itself dry your crawl space? Many contractors we encounter are telling homeowners that installing a sump pump will keep the crawl space dry. Is that true? The term dry can mean different things so is it referring to standing water or humidity?

What Sump Pumps Do

The sump pump is a mechanical device designed to direct water to a certain place. Normally crawl space sump pumps are placed in a sump pump basin that is buried in the ground. This placement allows the sump pump to be low in order for water to enter the basin via gravity. The sump pump basin helps protect the sump pump from soils and other debris to keep it running longer.

So, does the properly installed sump pump keep your crawl space dry? The sump pump can only address water that is directed into the basin for discharge. This has no affect on relative humidity or moisture in the wood or on the plastic. The sump pump cannot move groundwater on the opposite end of the crawl space unless it is directed to the sump pump.

Directing Groundwater to the Sump Pump

If your crawl space floods after heavy rains you should consider installing a water management or waterproofing system. The water management system directs water out of the crawl space. The waterproofing system keeps the water out of the crawl space. In our experience, most homes will need both.

Crawl Space Water Management

Crawl Space Ninja refers to a water management system as a french drain, sump pump basin, and sump pump properly installed in the ground to direct water from the crawl space. The water management system also needs a properly installed crawl space vapor barrier. This is to keep flood waters flowing to the water management system.

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Crawl Space Waterproofing

Crawl Space Ninja refers to waterproofing as the outside yard drainage system. The yard drainage was installed during the construction of your home. Contractors most likely applied a tar on the foundation wall and a footer drain around the outside perimeter.

Addressing the Flaws in Traditional Crawl Space Waterproofing Systems

The problem is the tar cracked and leaked instantly and the footer drain has probably clogged over time. This poorly installed foundation waterproofing system is now allowing outside ground water to enter the crawl space. Installing outside french drains and downspout extensions will help redirect roof and groundwater away from your foundation. This will normally not fix the flooded crawl space but is an important step along with the water management system.

Does a Sump Pump Dry the Air?

Back to the question of what does “dry” mean? If your crawl space has a humidity problem the sump pump is useless. Checking wood moisture levels to determine a potential mold issue is vital to eventually improving indoor air quality. Sump pumps move standing water out of the crawl space but do nothing against mold causing high humidity.

The Role of Sump Pumps in Crawl Space Moisture Management

If you are having your crawl space repaired to keep it dry. Make sure the sump pump, water management system, waterproofing system and a properly installed dehumidifier are part of the over all scope of work. Don’t allow contractors to install a system that will not address all the needs of your crawl space.

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What Next?

Contact us if you need help fixing your crawl space or yard drainage by clicking here.

Do you need help with controlling humidity in your home and you live in Alabama, Georgia, Delaware, North Carolina, South Carolina, Tennessee, or Kentucky? If so, please contact us to schedule your assessment. Also, let us know in the comments below if you’d like to suggest a future blog post.

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6 thoughts on “Misconception: A Sump Pump Will Dry My Crawl Space”

  1. Can a sump pump in a crawl space cause your house to settle?

    We built a new house with crawl space and have been in it 6 months now. The house is at the bottom of a hill and I noticed shortly after we moved in that we have significant ground water in the crawl space, isolated to one interior section of continuous footings. After 6 months, I recently finished properly installing a sump pump system and it works great….. no more standing water on the footing. Now it’s been two weeks and I noticed yesterday that the exterior door on the outside wall of the footing that had standing water is not locking – the dead bolt no longer lines up with the strike plate. Is it just coincidence or do you think removing the standing water caused the footing/block foundation to settle?

    Yikes! Any thoughts? Thank you …. BD in Little Rock

    1. Hi Brian, we have not had an issue of a sump pump creating a foundation settling problem. The water is probably the issue not the removal of the water. If your home is new the foundation footer drain should have been installed properly, emphasis on should have. If it was not, water can cause soil to move and erode under the footer. This can cause the footer to shift or settle. Or the footers may not be poured on bedrock. I would ensure downspouts are extended away from foundation and perhaps install a curtain drain if you are getting runoff from a hill. Try to locate where your footer drain is draining to, needs to drain to daylight. Builder should be able to show you this since it is so new. If you are still having issues, consult a structural engineer before it gets worse. I know a lady in Knoxville with new home that had to get footer jacked up due to poor building practices.

  2. hello

    had a company repair a sewer line and cut the french drain in process. turns out the french drain can not properly be repaird due to the newer line being smck dab in the route of the french drain. in addition….illl aslo need to replace encapulation where numerous cuts were made. could i just take a newere piece of encapulation and throw over the existing peice that has all the cuts?

    1. Hi Jesse, anytime we have tried this it has not worked effectively unless you thoroughly clean the old plastic so it can bond with new tape and the old plastic is pretty new. If you do that, it could work. Hope that helps.

  3. Eugene Landstrom

    Hi I wish you guys were up here in Montana I cannot find anyone that is knowledgeable in crawlspace moisture I have installed a dehumidifier to help but still get ground water coming up and it’s giving the dehumidifier a workout I want to install a sump pump and drains to it but it is beyond my capability du to my age and health condition
    So if you know anyone in the Missoula area that can help. Weill I would appreciate it

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