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How a Crawl Space Drainage System Works

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Water and moisture in a crawl space is never a good thing. A crawl space drainage system is designed to prevent moisture and water accumulation in the crawl space. But how exactly does it work?

A drainage system channels any water that enters the crawl space into a trench that leads to a sump pump that then directs the water out of the space away from the home. Our crews take the following steps when building a crawl space drainage system. (Not sure if you need one? Here are 
five signs you need a crawl space drainage system.)

  1. Dig a perimeter trench: Depending on the amount of water accumulation and the size of the crawl space, a trench will be dug around either the entire perimeter or along one wall or section. The trench is typically 8 inches deep, 8 inches wide and is installed around the interior perimeter of the crawl space, working with gravity to direct the water to drain into it. Once it is dug out, a perforated pipe is laid in the trench.
  2. Fill with gravel: A layer of gravel goes into the trench on top of and beside the perforated pipe. Gravel acts as a filter and helps the water to run evenly across the pipe.
  3. Install a sump pump: A hole is dug at the end of the trench at the lowest point, and a sump pump is installed. When water fills the hole from the drainage trench, the sump pump will kick on and suction the water out into a discharge pipe. The pipe directs the water to the outside of the house and away from the foundation.
  4. Install a moisture barrier or encapsulation: A moisture barrier placed on the ground of the crawl space prevents moisture from the ground from creeping into the space. While a drainage system and moisture barrier can prevent some moisture, if the crawl space has an open vent system, it will not prevent humidity from the air in the crawl space. For that reason, we strongly recommend that our customers go the extra step and fully encapsulate the crawl space. With full encapsulation, the crawl space floor, walls, and piers are wrapped with thick plastic barrier sheeting, and the vents are closed and sealed off. A dehumidifier is installed to maintain a healthy humidity level that prevents mold, wood rot, and structural damage. This air-tight space under your home will now be a healthier and more energy-efficient space.

Why wouldn't you prevent water from coming in to the crawl space?

Some customers ask why we allow the water to come into the crawl space in the first place. Wouldn’t it be better to prevent it from entering? In theory yes, but this is not always the best or most economical solution. Not to mention, stopping water is extremely challenging. With that being said, water does cause damage when it is not allowed to drain. If water is standing in your crawl space, that is a problem, but if it is directed to the outside through a proper drainage system, it will prevent any damage to your foundation. An exterior drainage and waterproofing system is an option, but it’s generally not recommended on existing homes when a crawl space system can be installed, as the installation is very disruptive and requires repair to landscaping and often utilities and structures such as decks and porches.

If you are unsure whether you need a crawl space drainage system in the Charlotte area, just reach out to schedule a free consultation with one of our experts. We can advise you on the best way to control water around your home and protect your investment.

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